View source for Biology:Glossary of bird terms

{{short description|Glossary of common English language terms used in the description of birds}}
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[[File:Birdmorphology.svg|thumb|upright=1.3|External anatomy ({{gli|topography}}) of a typical bird: 1&nbsp;{{gli|beak}}, 2&nbsp;{{gli|head}}, 3&nbsp;{{gli|iris}}, 4&nbsp;{{gli|pupil}}, 5&nbsp;{{gli|mantle}}, 6&nbsp;{{gli|lesser coverts}}, 7&nbsp;{{gli|scapulars}}, 8&nbsp;{{gli|coverts}}, 9&nbsp;{{gli|tertials}}, 10&nbsp;{{gli|rump}}, 11&nbsp;{{gli|primaries}}, 12&nbsp;{{gli|vent}}, 13&nbsp;{{gli|thigh}}, 14&nbsp;{{gli|tibio-tarsal articulation}}, 15&nbsp;{{gli|tarsus}}, 16&nbsp;{{gli|feet}}, 17&nbsp;{{gli|tibia}}, 18&nbsp;{{gli|belly}}, 19&nbsp;{{gli|flanks}}, 20&nbsp;{{gli|breast}}, 21&nbsp;{{gli|throat}}, 22&nbsp;{{gli|chin}}, 23&nbsp;{{gli|eyestripe}}]]

The following is a glossary of common English language terms used in the description of [[Biology:Bird|bird]]s—warm-blooded vertebrates of the [[Biology:Class|class]] Aves and the [[Biology:Origin of birds|only living dinosaurs]],<ref>{{Cite journal|last=Prum|first=Richard O. Prum|title=Who's Your Daddy?|journal=Science|volume=322|pages=1799–1800|date=19 December 2008|doi=10.1126/science.1168808|pmid=19095929|issue=5909|s2cid=206517571|doi-access=}}</ref> characterized by {{gli|feathers}}, the ability to {{gli|flight|fly}} in all but the approximately 60 extant species of flightless birds, toothless, {{gli|beak|beaked}} {{gli|mandible|jaws}}, the [[Biology:Oviparity|laying]] of [[Biology:Eggshell|hard-shelled]] eggs, a high metabolic rate, a four-chambered [[Biology:Heart|heart]] and a strong yet lightweight [[Biology:Bird skeleton|skeleton]]. 

Among other details such as size, proportions and shape, terms defining bird features developed and are used to describe features unique to the class—especially evolutionary adaptations that developed to aid [[Biology:Bird flight|flight]]. There are, for example, numerous terms describing the complex structural makeup of feathers (e.g., {{gli|barbules}}, {{gli|rachides}} and {{gli|vanes}}); types of feathers (e.g., {{gli|filoplume}}, {{gli|pennaceous}} and {{gli|plumulaceous}} feathers); and their growth and loss (e.g., {{gli|colour morph}}, {{gli|nuptial plumage}} and {{gli|pterylosis}}).

There are thousands of terms that are unique to the study of birds. This glossary makes no attempt to cover them all, concentrating on terms that might be found across descriptions of multiple bird species by bird enthusiasts and [[Biology:Ornithology|ornithologists]]. Though words that are not unique to birds are also covered, such as {{Nowrap|"{{gli|back}}"}} or {{Nowrap|"{{gli|belly}}"}}, they are defined in relation to other unique features of external [[Biology:Bird anatomy|bird anatomy]], sometimes called {{Nowrap|"{{gli|topography}}"}}. As a rule, this glossary does not contain individual entries on any of the approximately 11,000 recognized living individual bird species of the world. <ref>{{en}}{{aut|Gill, F, D Donsker, and P Rasmussen}} (Eds). 2024. IOC World Bird List (v 14.1). https://www.worldbirdnames.org</ref><ref name="Newton2003">{{cite book|last=Newton|first=Ian|title=The Speciation and Biogeography of Birds|url=https://books.google.com/books?id=E33oSw6j8UsC&pg=PA93|year=2003|publisher=Gulf Professional Publishing|isbn=978-0-12-517375-9|page=93}}</ref>{{efn|Ornithologists from the [[Biology:American Museum of Natural History|American Museum of Natural History]] suggested in a 2016 article published in ''PLOS ONE'', that the use of the "[[Biology:Species problem|biological species concept]]"—classifying a grouping of birds as making up a single [[Biology:Species|species]] by their ability to breed—is outdated and should be discarded in favour of a species' model that looks to similarity and dissimilarity in characteristics such as plumage, pattern and colouring to individuate bird species. Under such a model, it is suggested that there are ±18,000 individual living bird species in the world as of 2016.<ref>{{cite web|last=Waters|first=Hannah|date=December 15, 2016|publisher=National Audubon Society|title=New Study Doubles the World's Number of Bird Species By Redefining 'Species'|url=http://www.audubon.org/news/new-study-doubles-worlds-number-bird-species-redefining-species|archive-url=https://web.archive.org/web/20161221071917/http://www.audubon.org/news/new-study-doubles-worlds-number-bird-species-redefining-species|archive-date=December 21, 2016|url-status=dead}}</ref>}}

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==A==
{{Glossary}}
{{Term|addled eggs|content=addled eggs {{anchor|addled egg|addled|wind egg|wind eggs|hypanema}} }}
{{defn|''Also, '''wind eggs'''; '''hypanema'''.''<ref>{{cite book|title=Encyclopaedia perthensis, or, Universal dictionary of the arts, sciences, literature, etc.|url=https://books.google.com/books?id=tFYKAQAAMAAJ&pg=PA166|year=1816|publisher=John Brown|location=Edinburgh|page=166}}</ref> Eggs that are not viable and will not hatch.<ref name="Weaver12">{{Harvnb|Weaver|1981|p=12}}</ref> ''See related: {{gli|overbrooding}}.''}}

{{Term|afterfeather|content=afterfeather {{anchor|afterfeathers|after feather|after feathers|after-feather|after-feathers}} }}
{{defn|Any structure projecting from the shaft of the {{gli|feather}} at the rim of the {{gli|superior umbilicus}} (at the base of the {{gli|vanes}}), but typically a small area of downy {{gli|barbs}} growing in rows or as tufts.{{efn|[[Biology:Emu|Emu]]s and cassowaries are an exception in that their {{gli|afterfeathers}} are neither downy nor diminutive in relation to the vanes, but are comparable in size to them; such feathers are thus sometimes referred to as being "double plumed". The feathers of [[Biology:Ostrich|ostrich]] and [[Biology:Rhea (bird)|rhea]], also flightless birds, are by contrast "soft and filmy" in makeup, lacking any {{gli|barbules}} to add the stiffness needed in working {{gli|flight feathers}}.<ref name="Roots16">{{harvnb|Roots|2006|p=16}}</ref>}} Entirely absent in some birds—notably from many members of the [[Biology:Columbidae|Columbidae]] family (pigeons and doves)—afterfeathers can significantly increase the insulative attributes of a bird's {{gli|plumage}}.<ref name="Pettingill32">{{Harvnb|Pettingill|1985|p=32}}</ref>}}

{{Term|allopreening|content=allopreening {{anchor|allo-preening|allo preening}} }}
{{defn|A form of [[Biology:Social grooming|social grooming]] among birds, in which one bird {{gli|preen|preens}} another or a pair does so mutually. At times it may be used to redirect or sublimate aggression, such as one bird assuming a solicitation posture to indicate its non-aggression and invite allopreening by the aggressive individual.<ref name="MANDAL2012">{{cite book|last=Mandal|first=Fatik Baran|title=Textbook of Animal Behavior|url=https://books.google.com/books?id=FF-LDWalcqEC&pg=PA188|year=2012|publisher=PHI Learning Pvt. Ltd.|location=New Delhi|isbn=978-81-203-4519-5|page=188}}</ref>}}

{{Term|alternate plumage|content=alternate plumage {{anchor|alternate plumages|nuptial plumage|nuptial plumages|breeding plumage|breeding plumages}} }}
{{defn|''Also, '''nuptial plumage'''; '''breeding plumage'''.'' The plumage of birds during the courtship or breeding season. It results from a {{gli|prealternate moult}} that many birds undergo just prior to the season. The alternate plumage is commonly brighter than the {{gli|basic plumage}}, for the purposes of sexual display, but may also be {{gli|cryptic}}, to hide incubating birds that might be vulnerable on the nest.<ref name="Humphrey–Parks">{{cite magazine|magazine=The Auk|date=January 1959|last1=Humphrey|first1=Philip S.|last2=Parkes|first2=Kenneth C.|volume=76|issue= 1|pages=1–31|title=An Approach to the Study of Molts and Plumage|jstor=4081839|doi=10.2307/4081839}}</ref>}}

{{Term|altricial|content=altricial {{anchor|semi-altricial|semialtricial|semi altricial}} }}
{{defn|''Also defined: '''semi-altricial'''; '''altricial-precocial spectrum'''.''  Young that, at hatching, have their eyes closed; are naked or only sparsely covered in {{gli|down feathers}} ({{gli|psilopaedic}}); are not fully able to regulate their body temperature ([[Biology:Ectotherm|ectotherm]]ic);<ref name="SummersCrespi2013">{{cite book|last1=Summers|first1=Kyle |last2=Crespi|first2=Bernard |title=Human Social Evolution: The Foundational Works of Richard D. Alexander|url=https://books.google.com/books?id=j39rQ9yfwrwC&pg=PT192|year=2013|publisher=Oxford University Press|isbn=978-0-19-933963-1|page=192}}</ref> and are unable to walk or leave the nest for an extended period of time to join their parents in {{gli|foraging}} activities ({{gli|nidicolous}}), whom they rely on for food.<ref name="Howell2014">{{cite book|last=Howell|first=Steve N. G.|title=Peterson Reference Guide to Molt in North American Birds|url=https://books.google.com/books?id=eQU-BAAAQBAJ&pg=PA8|year=2014|publisher=Houghton Mifflin Harcourt|isbn=978-0-547-48769-4|page=8}}</ref> The contrasting state is {{gli|precocial}} young, which are born more or less with their eyes open, covered in down, homeothermic, able to leave the nest and ambulate and to participate in foraging.<ref name="SummersCrespi2013"/><ref name="Johnston2013">{{cite book|last=Johnston|first=Richard|title=Current Ornithology|url=https://books.google.com/books?id=riYBCAAAQBAJ&pg=PA34|year=2013|publisher=Springer Science & Business Media|isbn=978-1-4615-6781-3|page=34}}</ref> The young of many bird species do not precisely fit into either the precocial or altricial category, having some aspects of each and thus fall somewhere on an ''altricial-precocial spectrum''.<ref name="Urfi2011">{{cite book|last=Urfi|first=A. J.|title=The Painted Stork: Ecology and Conservation|url=https://books.google.com/books?id=_9tczTapYXMC&pg=PA88|year=2011|publisher=Springer Science & Business Media|isbn=978-1-4419-8468-5|page=88}}</ref> A defined intermediate state is termed ''semi-altricial'', typified by young that, though born covered in down ({{gli|ptilopaedic}}), are unable to leave the nest or walk and are reliant on their parents for food.<ref name="Scott2008">{{cite book|last=Scott|first=Lynnette|title=Wildlife Rehabilitation|url=https://books.google.com/books?id=FpAOAQAAMAAJ|year=2008|publisher=National Wildlife Rehabilitators Association|isbn=978-1-931439-23-7|page=50}}</ref><ref name="Pettingill371">{{harvnb|Pettingill|2013|p=371}}</ref>}}

[[File:Alula.png|thumb|alt=Drawing of the various parts of a bird's wing|Location of the {{gli|alula}} on a bird's wing]]
{{Term|alula|content=alula {{anchor|alulae|alulas|bastard wing|bastard wings|bastard-wing|bastard-wings|thumb|thumbs|ala|alular digit|alular digits|alular quill|alular quills}} }}
{{Main|Biology:Alula}}
{{defn|''Also, '''bastard wing'''; '''alular digit'''; '''alular quills'''.''<ref name="Pettingill16-21"/> A small, freely-moving projection on the anterior edge of the wing of modern [[Biology:Bird|bird]]s (and a few non-avian dinosaurs)—a bird's "thumb"—the word is Latin and means 'winglet'; it is the diminutive of ''ala'', meaning 'wing'. Alula typically bear three to five small {{gli|flight feathers}}, with the exact number depending on the species. The bastard wing normally lies flush against the anterior edge of the wing proper, but can be raised to function in similar manner to the slats of airplane wings that aid in [[Physics:Lift (force)|lift]] by allowing a higher than normal [[Physics:Angle of attack|angle of attack]]. By manipulating the alula structure to create a gap between it and the rest of the wing, a bird can avoid stalling when flying at low speeds or when landing. Feathers on the alular digit are not generally considered to be {{gli|flight feathers}} in the strict sense; though they are asymmetrical, they lack the length and stiffness of most true flight feathers. Nevertheless, alula feathers are a distinct aid to slow flight.<ref name="Campbell656"/>}}

{{Term|anisodactylous|content=anisodactylous|anisodactyl|anisodactyl feet|anisodactylous feet|anisodactyl foot|anisodactylous foot}}
{{defn|Descriptive of tetradactyl (four-toed) birds in which the architecture of the foot consists of three toes projecting forward and one toe projecting backward (the {{gli|hallux}}), such as in most {{gli|passerine}} species.<ref name="Pettingill187">{{Harvnb|Pettingill|1985|p=187}}</ref><ref name="Gill59–61">{{Harvnb|Gill|1995|pp=59–61}}</ref>}}

{{Term|anting|content=anting {{anchor|ant|bird anting|passive anting}} }}
{{Main|Biology:Anting (bird activity)}}
{{defn|''Also defined: '''passive anting'''.'' A [[Biology:Self-anointing in animals|self-anointing]] behaviour during which birds rub insects, usually [[Biology:Ant|ant]]s and sometimes [[Biology:Millipede|millipede]]s, on their {{gli|feathers}} and skin. Anting birds may pick up the insects in their {{gli|bill}} and rub them on their bodies, or may simply lie in an area with a high density of the insects and perform [[Biology:Dust bathing|dust bathing]]-like movements. Insects used for anting secrete chemical liquids such as [[Chemistry:Formic acid|formic acid]], which can act as [[Biology:Insecticide|insecticide]]s, miticides, [[Biology:Fungicide|fungicide]]s and bactericides. The practice may also act to supplement a bird's own [[Biology:Uropygial gland|preen oil]]. A third purpose may be to render the insects more palatable, by causing removal of distasteful compounds. More than 200 species of bird are known to ant.<ref name="Osborn">{{cite magazine|magazine=The Wilson Bulletin|first=Sophie A. H.|last=Osborn|title=Anting by an American Dipper (''Cinclus mexicanus'')|volume=110|issue= 3|date=September 1998|pages=423–425|url = https://sora.unm.edu/sites/default/files/journals/wilson/v110n03/p0423-p0425.pdf}}</ref> "Passive anting" refers to when birds simply position themselves so as to allow insects to crawl through their plumage.<ref name="Weaver12"/>}}

[[File:Gull of Gibraltar (8483055557).jpg|thumb|upright=1.15|A [[Biology:Yellow-legged gull|yellow-legged gull]] (''Larus michahellis'') in flight. {{gli|Apical spots}} tinge the row of feathers on the trailing edges of its wings.]]
{{Term|apical spot|content=apical spot {{anchor|apical spots|apical-spot|apical-spots}} }}
{{defn|A visible spot near the outer tip of a feather.<ref name="AlderferDunn2007">{{cite book|last1=Alderfer|first1=Jonathan K. |last2=Dunn|first2=Jon|title=National Geographic Birding Essentials: All the Tools, Techniques, and Tips You Need to Begin and Become a Better Birder|url=https://archive.org/details/nationalgeograph00jona|url-access=registration|date=January 2007|publisher=National Geographic|isbn=978-1-4262-0135-6|page=[https://archive.org/details/nationalgeograph00jona/page/216 216]}}</ref>}}

{{Term|apterylae|content=apterylae {{anchor|apteria}} }}
{{defn|''Singular: '''apteryla'''.'' ''Also, '''apteria'''''. Regions of a bird's skin, between the {{gli|pterylae}} (feather tracts), which are free of {{gli|contour feathers}}; {{gli|filoplumes}} and {{gli|down}} may grow in these areas.<ref name="Proctor98">{{Harvnb|Proctor|Lynch|1998|p=98}}</ref><ref name="UlmerHaupt1962">{{cite book|last1=Ulmer|first1=Martin John|last2=Haupt|first2=Robert E.|last3=Hicks|first3=Ellis A.|title=Comparative Chordate Anatomy: A Laboratory Manual|url=https://books.google.com/books?id=Xno_AAAAYAAJ|year=1962|publisher=Harper & Row|page=169}}</ref> ''See related: {{gli|pterylosis}}''.}}

{{Term|aviculture|content=aviculture}}
{{defn|The captive breeding and keeping of birds.<ref name="Weaver12"/>}}

{{Term|axilla|content=axilla {{anchor|axillar region|axillar|axillars|underarm|underarms|armpit|arm pit|under arm}} }}
{{defn|''Also, '''axillar region'''; "'''underarm'''"; "'''armpit'''".'' The "armpit" of a bird, often hosting {{gli|covert feathers}} called {{Nowrap|{{gli|axillaries}}.<ref>{{Harvnb|Newton, et al.|1899|p=25}}</ref>}}}}

{{Term|axillaries|content=axillaries {{anchor|axillary feathers|lower humeral coverts|hypopteron}} }}
{{defn|''Also, '''axillary feathers'''; '''lower humeral coverts'''; '''hypopteron'''.'' {{gli|Covert feathers}} found in the {{gli|axillar region}} or "armpit" of a bird, which are typically long, stiff and white in colour.<ref name="Campbell60">{{Harvnb|Campbell|Lack|1985|p=60}}</ref>}}

{{Glossary end}}

==B==
{{Glossary}}
[[File:Feather_zipping_microstructure.svg|thumb|Explanatory diagram showing the interlocking of the {{gli|barbs}} of {{gli|feathers}}]]
{{Term|back|content=back {{anchor|backs}} }}
{{defn|The exterior region of a bird's upper parts between the {{gli|mantle}} and the {{gli|rump}}.<ref name="Vinicombe15"/>}}

{{Term|barb|content=barb {{anchor|barbs|ramus|rami}} }}
{{defn|''Also defined: '''ramus''' (plural: '''rami''').'' The individual structures growing out of the {{gli|shaft}} that collectively make up the {{gli|vanes}} of the feathers, more or less interconnected by the {{gli|hooklets}} of the {{gli|barbules}}, extending from each side of the distal part of the feather's shaft known as the {{gli|rachis}}. The central axis of a barb is known as the ramus.<ref name="Pettingill32"/>}}

{{Term|barbules|content=barbules {{anchor|proximal barbules|distal barbules|barbule|barbicel|barbicels|hooklet|hooklets|pennulum|teeth|cilia}} }}
{{defn|''Also, '''radius'''&thinsp;/&thinsp;'''radii'''; '''tertiary fibres'''.''<ref name="Chandler252">{{Harvnb|Chandler|1916|p=252}}</ref>  ''Also defined: '''proximal barbules'''; '''distal barbules'''; '''barbicels'''; '''hooklets''' ('''hamuli'''); '''pennulum'''; '''teeth'''.'' Just as {{gli|barbs}} branch off on parallel sides of the {{gli|rachis}}, the barbs in turn have a set of structures called barbules, branching from each side of the {{gli|ramus}}. The base cells of the barbule form a plate from which a thinner stalk projects called the pennulum. At one more level of branching, the pennulum hosts small outgrowths from it called barbicels—which when found on {{gli|pennaceous feathers}}, vary in structure depending on which side of a barb's ramus they project from. Proximal barbules (on the proximal side of the ramus) have ventral projections near the base called teeth, while growing from the pennulum are cilia—simple pointed structures. At the base of the proximal barbule, the "dorsal edge is recurved into a {{gli|flange}}".<ref name="Pettingill32-33">{{Harvnb|Pettingill|1985|pp=32–33}}</ref> The distal barbules (on the distal side of the ramus) have a thicker base with more elaborate teeth, and a longer pennulum with hooklets (also called hamuli<ref name="Allen1951">{{cite book|last=Allen|first=Elsa Guerdrum|title=The History of American Ornithology Before Audubon|url=https://books.google.com/books?id=T4UpAQAAMAAJ|year=1951|publisher=Russell & Russell|page=458}}</ref>) at the end, as well as cilia in greater number than on proximal barbules. The hooklets overlap one to four rows of proximal barbules on the next higher barb, locking into their flanges, thereby giving the {{gli|vane}} structure, strength, flexibility and stability.<ref name="Pettingill32-33"/> ''See also: {{gli|friction barbules}}.''}}

{{Term|basic plumage|content=basic plumage {{anchor|basic plumages|non-breeding plumage|non-breeding plumages|nonbreeding plumage|nonbreeding plumages|non breeding plumage|non breeding plumages|winter plumage|winter plumages|supplementary plumage|supplementary plumages}} }}
{{defn|''Also, '''winter plumage'''; '''non-breeding plumage'''. Also defined: '''supplementary plumage'''.'' The plumage of birds during the non-breeding season. It results from the {{gli|prebasic moult}} that many birds undergo just after the season, and sometimes (rarely) even a second non-breeding season moult (resulting in what's termed "supplementary plumage") prior to the next breeding season.{{efn|Birds that undergo a second, non-breeding season moult (third moult overall) include: [[Biology:Lagopus|ptarmigans]] (''Lagopus'') (in the summer); [[Biology:Long-tailed duck|long-tailed duck]] (''Clangula hyemalis'') (in the winter); [[Biology:Ruff (bird)|ruff]] (''Philomachus pugnax'') (in the late winter or early spring); and may occur in other members of the [[Biology:Sandpiper|sandpiper]] (Scolopacidae) family.<ref name="Pettingill189-192">{{Harvnb|Pettingill|1985|pp=189–192}}</ref>}} The basic plumage is commonly duller than the {{gli|alternate plumage|alternate or nuptial plumage}}.<ref name="Humphrey–Parks"/><ref name="Pettingill189-192"/>}}

[[File:BirdBeaksA.svg|thumb|Comparison of bird {{gli|bills}}, displaying different shapes adapted to different feeding methods (not to scale)]]
{{Term|beak|content=beak {{anchor|bill|bills|beaks|rostrum|beaked}} }}
{{defn|''Also, '''bill''' or '''rostrum'''.'' An external anatomical structure of a bird's head, roughly corresponding with the "nose" of a mammal, that is used for eating, [[Biology:Personal grooming#In animals|grooming]], manipulating objects, killing prey, fighting, probing for food, [[Biology:Courtship display|courtship]] and feeding young. Although beaks vary significantly in size and shape from species to species, their underlying structures follow a similar pattern. All beaks are composed of two jaws, generally known as the {{gli|upper mandible}} (or maxilla) and {{gli|lower mandible}} (or mandible),<ref name="Coues">{{Harvnb|Coues|1890|p=198}}</ref> covered with a thin, horny sheath of [[Biology:Keratin|keratin]] called the {{Nowrap|{{gli|rhamphotheca}},<ref name="Proctor66">{{Harvnb|Proctor|Lynch|1998|p=66}}</ref><ref name="Gill148">{{Harvnb|Gill|1995|p=148}}</ref>}} which can be subdivided into the {{gli|rhinotheca}} of the upper mandible and the {{gli|gnathotheca}} of the lower mandible.<ref name="Campbell47">{{Harvnb|Campbell|Lack|1985|p=47}}</ref> The {{gli|tomia}} (''singular: tomium'') are the cutting edges of the two mandibles.<ref name="Campbell598">{{Harvnb|Campbell|Lack|1985|p=598}}</ref> Most species of birds have external {{gli|nares}} (nostrils) located somewhere on their beak—two holes—circular, oval or slit-like in shape—which lead to the nasal cavities within the bird's skull, and thus to the rest of the [[Biology:Bird anatomy#Respiratory system|respiratory system]].<ref name="Campbell375">{{Harvnb|Campbell|Lack|1985|p=375}}</ref> Although the word ''beak'' was, in the past, generally restricted to describing the sharpened bills of birds of prey,<ref name="Partington">{{cite book|last=Partington|first=Charles Frederick|title=The British cyclopæedia of natural history: combining a scientific classification of animals, plants, and minerals|url=https://archive.org/details/britishcyclopd02partrich|year=1835|publisher=Orr & Smith|page=[https://archive.org/details/britishcyclopd02partrich/page/417 417]}}</ref> in modern [[Biology:Ornithology|ornithology]], the terms ''beak'' and ''bill'' are generally used synonymously.<ref name="Proctor66"/>}}

{{Term|beak colour|content=beak colour {{anchor|beak colours|beak colouring|beak color|beak colors|beak coloring}} }}
{{defn|The colour of a bird's beak results from concentrations of pigments—primarily [[Chemistry:Melanin|melanin]]s and carotenoids—in the epidermal layers, including the {{gli|rhamphotheca}}.<ref>{{cite magazine|magazine=American Zoologist|volume=9|issue= 2|pages=521–530|title=The Control of Color in Birds|date=May 1969|first=Charles L.|last=Ralph|jstor=3881820|doi=10.1093/icb/9.2.521|pmid=5362278|doi-access=free}}</ref> In general, beak colour depends on a combination of the bird's [[Biology:Hormone|hormonal state]] and diet. Colours are typically brightest as the breeding season approaches and palest after breeding.<ref name="Howell23"/>}}

{{Term|beak trimming|content=beak trimming {{anchor|debeaking|coping}} }}
{{Main|Biology:Debeaking}}
{{defn|''Also, '''debeaking''' and '''coping'''.'' The partial removal of the {{gli|beak}} of poultry, especially [[Biology:Chicken|layer hens]] and turkeys, although it may also be performed on [[Biology:Quail|quail]] and ducks. Because the beak is a sensitive organ with many sensory receptors, beak trimming or debeaking is "acutely painful"<ref name="Grandin">{{cite book |title=Improving Animal Welfare: A Practical Approach |first=Temple |last=Grandin |publisher=CABI |location=Oxfordshire, UK |year=2010 |page=110 |isbn=978-1-84593-541-2}}</ref> to the birds it is performed on. It is nonetheless routinely done to intensively farmed bird species, because it helps reduce the damage the flocks inflict on themselves due to a number of [[Medicine:Stress|stress]]-induced behaviours, including cannibalism, {{gli|vent pecking}} and {{gli|feather pecking}}. A cauterizing blade or infrared beam is used to cut off about half of the upper beak and about a third of the lower beak. Pain and sensitivity can persist for weeks or months after the procedure, and neuromas can form along the cut edges. Food intake typically decreases for some period after the beak is trimmed. However, studies show that trimmed poultry's adrenal glands weigh less, and their plasma [[Chemistry:Corticosterone|corticosterone]] levels are lower than those found in untrimmed poultry, indicating that they are less stressed overall.<ref name="Grandin"/> A less radical, separate practice, usually performed by an avian veterinarian or an experienced birdkeeper, involves clipping, filing or sanding the beaks of captive birds for health purposes—in order to correct or temporarily alleviate overgrowths or deformities and better allow the bird to go about its normal feeding and preening activities.<ref name=fostersmith>{{cite web|title=Bird Beaks: Anatomy, Care, and Diseases|url=http://www.peteducation.com/article.cfm?c=15+1829&aid=2752|publisher=Veterinary & Aquatic Services Department, Drs. Foster & Smith|access-date=January 29, 2017|archive-url=https://web.archive.org/web/20120604232117/http://www.peteducation.com/article.cfm?c=15+1829&aid=2752|archive-date=June 4, 2012|url-status=dead}}</ref>  "Coping" is the name for this practice amongst [[Biology:Bird of prey|raptor]] keepers.<ref name=ash>{{cite web|last=Ash|first=Lydia|title=Coping your Raptor|url=http://www.themodernapprentice.com/coping.htm|publisher=The Modern Apprentice|access-date=January 29, 2017}}</ref>}}

{{Term|belly|content=belly {{anchor|abdomen|abdomens|bellies}} }}
{{defn|''Also, '''abdomen'''.'' The {{gli|topography|topographical}} region of a bird's {{gli|underparts}} between the posterior end of the breast and the {{gli|vent}}.<ref>{{cite book|last1=Baird|first1=Spencer Fullerton|last2=Brewer|first2=Thomas Mayo|last3=Ridgway|first3=Robert|title=A History of North American Birds|url=https://books.google.com/books?id=PF8MAQAAIAAJ&pg=PA554|year=1874|publisher=Little, Brown|page=535}}</ref>}}

{{Term|billing|content=billing {{anchor|nebbing}} }}
{{defn|''Also, '''nebbing''' (chiefly UK).'' Describes the tendency of mated pairs of many bird species to touch or clasp each other's {{gli|bills}}.<ref>{{Cite news|url=http://articles.chicagotribune.com/2004-08-12/features/0408120087_1_catholic-cardinals-billing-cain-and-abel |title=Add this to life list: 'Birding' has inspired flock of words |first=Nathan|last=Bierma |newspaper=Chicago Tribune|date=August 12, 2004}}</ref> This behaviour appears to strengthen [[Philosophy:Pair bond|pair bond]]ing.<ref name="Terres232">{{harvnb|Terres|1980|p=232}}</ref> The amount of contact involved varies among species. Some gently touch only a part of their partner's beak while others clash their beaks vigorously together.<ref>{{cite book |title=Biology of Marine Birds |editor1-first=Elizabeth Anne |editor1-last=Schreiber |editor2-first=Joanna |editor2-last=Burger |year=2002 |location=Boca Raton, FL |publisher=CRC Press |isbn=978-0-8493-9882-7 |page=325}}</ref>}}

{{Term|bill tip organ|content=bill tip organ {{anchor|bill tip organs|billtip organ|billtip-organbilltip-organs|bill-tip organ|bill-tip organs}} }}
{{defn|A region found near the tip of the {{gli|bill}} in several types of birds that forage particularly by probing. The region has a high density of nerve endings known as the {{gli|corpuscles of Herbst}}. These consist of pits in the bill's surface lined with cells that sense pressure changes. The assumption is that these cells allow a bird to perform "remote touch", meaning that it can detect the movement of animals by pressure variations in water, without directly touching the prey. Bird species known to have bill-tip organs include [[Biology:Ibis|ibis]]es, shorebirds of the family [[Biology:Scolopacidae|Scolopacidae]] and [[Biology:Kiwi (bird)|kiwi]]s.<ref name="Cunningham&Alley">{{cite magazine|first1=Susan J.|last1=Cunningham|first2=Maurice R.|last2=Alley|first3=Isabel|last3=Castro|first4=Murray A.|last4=Potter|first5=Malcolm|last5=Cunningham|first6=Michael J.|last6=Pyne|title=Bill morphology of Ibises suggests a remote-tactile sensory system for prey detection|magazine=The Auk|year=2010|volume=127|issue= 2|pages=308–316|doi=10.1525/auk.2009.09117|s2cid=85254980}}</ref>}}

[[File:Pitta guajana-20030531.jpg|thumb|upright=0.8|A female [[Biology:Javan banded pitta|Javan banded pitta]] (''Hydrornis guajanus''), with a numbered ring {{gli|banding}} its left leg]]
{{Term|bird ringing|content=bird ringing {{anchor|bird banding|ringing|banding}} }}
{{defn|''Also, '''bird banding'''.'' The attachment of small, individually numbered metal or plastic tags to the legs or wings of wild birds to enable individual identification. The practice helps in keeping track of bird movement and life history. Upon capture for ringing, it is common to take measurements and examine the conditions of feather {{gli|moult}}, amount of subcutaneous fat, age indications and sex. The subsequent recapture or recovery of banded birds can provide information on migration, longevity, mortality, population, territoriality, feeding behaviour and other aspects that are studied by ornithologists. ''Bird ringing'' is the term used in the UK and in some other parts of Europe, while the term ''bird banding'' is more often used in the U.S. and Australia.<ref name="BusseMeissner2015">{{cite book|last1=Busse|first1=Przemyslaw|last2=Meissner|first2=Wlodzimierz|title=Bird Ringing Station Manual|url=https://books.google.com/books?id=VxHuCAAAQBAJ|year=2015|publisher=De Gruyter|location=Warsaw|isbn=978-83-7656-053-3}}</ref>}}

{{Term|bird strike|content=bird strike {{anchor|bird strikes}} }}
{{defn|The impact of a bird or birds with an airplane in flight.<ref name="Weaver23">{{Harvnb|Weaver|1981|p=23}}</ref>}}

{{Term|body down|content=body down {{anchor|body-down|body-down feather|body-down feathers|body down feather|body down feathers}} }}
{{defn|The layer of small, fluffy {{gli|down}} feathers that lie underneath the outer {{gli|contour feathers}} on a bird's body.<ref name="Sibley17">{{Harvnb|Sibley, et al.|2001|p=17}}</ref> ''Compare: {{gli|natal down}} and {{gli|powder down}}''.}}

{{Term|breast|content=breast {{anchor|breasts}} }}
{{defn|The {{gli|topography|topographical}} region of a bird's external anatomy between the {{gli|throat}} and the {{gli|belly}}.<ref name="Weaver24">{{Harvnb|Weaver|1981|p=24}}</ref>}}

{{Term|breeding plumage}}
{{defn|''See {{gli|alternate plumage}}.''}}

{{Term|brood|content=brood {{anchor|broods}} }}
{{defn|The collective term for the offspring of birds, or the act of {{gli|egg incubation|brooding}} the eggs.<ref>{{cite book|editor-last=Vuilleumier|editor-first=françois|title=American Museum of Natural History Birds of North America Eastern Region|url=https://books.google.com/books?id=yRFpR-D2O1sC&pg=RA24-PA473|year=2011|publisher=DK Publishing|isbn=978-0-7566-7387-1|page=473}}</ref>}}

{{Term|brooding}}
{{defn|''See {{gli|egg incubation}}.''}}

{{Term|broodiness|content=broodiness {{anchor|broody}} }}
{{Main|Biology:Broodiness}}
{{defn|''Also defined: '''broody'''.'' The action or behavioural tendency of a bird to sit on a {{gli|clutch}} of eggs to {{gli|egg incubation|incubate}} them, often requiring the non-expression of many other behaviours including feeding and drinking.<ref name="RanquiniGarcia1958">{{cite book|last1=Ranquini|first1=Juan Homedes|last2=Garcia|first2=Francisco Haro|title=Zoogenética|url=https://books.google.com/books?id=vRVBAAAAYAAJ|year=1958|publisher=Salvat}}</ref> The adjective "broody" is defined as "[b]eing in a state of readiness to brood eggs that is characterized by cessation of laying and by marked changes in behavior and physiology". Example usage: "a broody hen".<ref>{{cite web|url=http://www.merriam-webster.com/dictionary/broody|title=Merriam-Webster definition|access-date=March 12, 2017}}</ref> }}

{{Term|brood patch|content=brood patch {{anchor|brood patches}} }}
{{defn|A bare patch of skin that most female birds gain during the nesting season for [[Physics:Thermoregulation|thermoregulation]] purposes, by shedding feathers close to the belly, in an area that will be in contact with the eggs during {{gli|incubation}}. The patch of bare skin is well supplied with blood vessels at the surface, facilitating heat transfer to the eggs.<ref>{{cite magazine|last=Turner|first=J. Scott|year=1997|title=On the thermal capacity of a bird's egg warmed by a brood patch|magazine=Physiological Zoology |volume=70|issue= 4|pages=470–80|doi=10.1086/515854|pmid=9237308}}</ref>}}

{{Term|brood parasite|content=brood parasite {{anchor|brood parasites|brood parasitism}} }}
{{defn|Birds, such as the common goldeneye, indigobirds, [[Biology:Viduidae|whydahs]], [[Biology:Honeyguide|honeyguide]]s, [[Biology:Cowbird|cowbird]]s and New World cuckoos, that lay their eggs in other birds' nests, in order to have their chicks {{gli|incubated}} through {{gli|fledging}} by the parents of another bird, often of another species.<ref>{{cite magazine | last1=Aragon| first1=S.|last2=Møller | first2=A. P.|last3=Soler|first3=J. J.|last4=Soler|first4=M.|year=1999|title=Molecular phylogeny of cuckoos supports a polyphyletic origin of brood parasitism|magazine=Journal of Evolutionary Biology|volume=12|issue= 3|pages=495–506|doi=10.1046/j.1420-9101.1999.00052.x| s2cid=16923328}}</ref><ref>{{cite magazine|last1=Sorenson|first1=M.D.|last2=Payne|first2=R.B.|year=2001|title=A single ancient origin of brood parasitism in African finches: implications for host-parasite coevolution|magazine=Evolution|volume=55|issue= 12|pages=2550–2567| doi=10.1554/0014-3820(2001)055[2550:asaoob]2.0.co;2|pmid=11831669|hdl=2027.42/72018|url=https://deepblue.lib.umich.edu/bitstream/2027.42/72018/1/j.0014-3820.2001.tb00768.x.pdf}}</ref><ref>{{cite magazine|last1=Sorenson|first1=M.D. |last2=Payne|first2=R.B.|year=2002|title=Molecular genetic perspectives on avian brood parasitism|magazine=Integrative and Comparative Biology|volume=42|issue= 2|pages=388–400|doi=10.1093/icb/42.2.388|pmid=21708732|doi-access=free}}</ref>}}

{{Glossary end}}

==C==
{{Glossary}}
{{Term|calamus|content=calamus {{anchor|calami}} }}
{{defn|''Plural: '''calami'''.'' The basal part of the {{gli|quill}} of {{gli|pennaceous feathers}}, which embeds at its proximal tip in the skin of a bird. The calamus is hollow and has pith formed from the dry remains of the feather pulp. The calamus stretches between two openings—at its base is the {{gli|inferior umbilicus}} and at its distal end is the {{gli|superior umbilicus}}; the {{gli|rachis}} of the stem, hosting the {{gli|vanes}}, continues above it.<ref name="Ritchison"/><ref name="Chandler250"/> Calamus derives from the Latin for 'reed' or 'arrow'.<ref>{{cite web|url=http://www.latin-dictionary.net/search/latin/calamus|title=Latin Dictionary|access-date=May 1, 2020}}</ref>}}

{{Birdsong|url=http://www.xeno-canto.org/explore?query=Gaviidae|species=loons|song1=loons.ogg|caption song1=The haunting {{gli|call}} of the [[Biology:Loon|loon]]}}
{{Term|call|content=call {{anchor|calls|alarm call|alarm calls|mobbing call|mobbing calls|duet call|diet calls|food begging call|food begging calls|antiphonal duetting|antiphonal|antiphonal duet|flight call|flight calls|calling}} }}
{{Main|Biology:Bird vocalization}}
{{defn|''Specific types: '''alarm'''; '''contact'''; '''duet'''; '''antiphonal duetting'''; '''food begging'''; '''flight'''; '''mobbing'''.'' A type of bird vocalization tending to serve such functions as giving alarm or keeping members of a [[Biology:Herd|flock]] in contact—as opposed to a bird's {{gli|song}}, which is longer, more complex and is usually associated with [[Biology:Bird#Breeding|courtship and mating]].<ref name="Voices">{{cite web|last1=Ehrlich|first1=Paul R.|last2= Dobkin|first2=David S.|last3=Wheye|first3=Darryl|url=https://web.stanford.edu/group/stanfordbirds/text/uessays/essays_alpha.html|title="Bird Voices" and "Vocal Development" from Birds of Stanford essays|access-date=9 September 2008}}</ref> Individual birds may be sensitive enough to identify each other through their calls. Many birds that nest in colonies can locate their chicks using their calls.<ref>{{cite magazine|last1=Lengagne|first1=T.|last2=Lauga|first2=J.|last3=Aubin|first3=T.|year=2001|title=Intra-syllabic acoustic signatures used by the King Penguin in parent-chick recognition: an experimental approach|magazine=The Journal of Experimental Biology |volume=204| pages=663–672|url=http://jeb.biologists.org/cgi/reprint/204/4/663.pdf|pmid=11171348|issue=Pt. 4}}</ref> ''Alarm calls'' are used to sound alarm to other individuals. ''Food-begging calls'' are made by baby birds to beg for food, such as the "''wah''" of infant [[Biology:Blue jay|blue jay]]s.<ref name="MacKay2001">{{cite book|last=MacKay|first=Barry Kent|title=Bird Sounds: How and why Birds Sing, Call, Chatter, and Screech|url=https://books.google.com/books?id=LsTZcR92uPgC&pg=PA28|date=January 2001 |publisher=Stackpole Books|isbn=978-0-8117-2787-7|page=28}}</ref> ''[[Biology:Mobbing (animal behavior)#Mobbing calls|Mobbing calls]]'' signal other individuals in [[Biology:Mobbing (animal behavior)|mobbing]] species while harassing a predator. They differ from alarm calls, which alert other species members to allow ''escape'' from predators. As an example, the [[Biology:Great tit|great tit]], a European songbird, uses such a signal to call on nearby birds to harass a perched [[Biology:Bird of prey|bird of prey]], such as an owl. This call occurs in the 4.5kHz range,<ref>{{cite book|last=Alcock|first=John|year=1998|title=Animal Behavior: An Evolutionary Approach|edition=6th|publisher=Sinauer Associates|location=Sunderland|isbn=978-0-87893-009-8|url=https://archive.org/details/animalbehaviorev00alco_1}}</ref> and carries over long distances. However, when such prey species are in flight, they employ an alarm signal in the 7–8&nbsp;kHz range. This call is less effective at traveling great distances, but is much more difficult for both owls and hawks to hear (and detect the direction from which the call came).<ref>{{cite magazine|last=Brown|first=C. H.|year=1982|title=Ventriloquial and locatable vocalizations in birds|magazine=Zeitschrift für Tierpsychologie | volume=59|issue= 4|pages=338–350|doi=10.1111/j.1439-0310.1982.tb00346.x}}</ref> ''Contact calls'' are used by birds for the purpose of letting others of their species know their location.<ref name="Weaver34"/> Relatedly, ''flight calls'' are vocalizations made by birds while flying, which often serve to keep flocks together.<ref name="Sibley68–69">{{Harvnb|Sibley, et al.|2001|pp=68–69}}</ref> These calls are also used for when birds want to alert others that they are taking flight.<ref name="Rowinski2011">{{cite book|last=Rowinski|first=Kate|title=The Joy of Birding: A Beginner's Guide|url=https://books.google.com/books?id=Ise4k6tJpQAC&pg=PA22|year=2011|publisher=Skyhorse Publishing Inc.|isbn=978-1-61608-122-5|pages=22–}}</ref> Many birds engage in ''duet calls''—a call made by two birds at or nearly at the same time. In some cases, the duets are so perfectly timed as to appear almost as one call. This kind of calling is termed ''antiphonal duetting''.<ref>{{cite magazine|author=Thorpe, W. H.|magazine=Nature|volume=197|pages=774–776|year=1963|doi=10.1038/197774a0|title=Antiphonal Singing in Birds as Evidence for Avian Auditory Reaction Time|issue= 4869|bibcode=1963Natur.197..774T|s2cid=30542781}}</ref> Such duetting is noted in a wide range of families including quails,<ref>{{cite magazine|last1=Stokes|first1=A. W.|last2=Williams|first2=H. W.|year=1968|title=Antiphonal calling in quail|magazine=Auk|volume=85|issue= 1|pages=83–89|url=http://sora.unm.edu/sites/default/files/journals/auk/v085n01/p0083-p0089.pdf|doi=10.2307/4083626|jstor=4083626}}</ref> [[Biology:Bushshrike|bushshrike]]s,<ref>{{cite book|last1=Harris|first1=Tony |last2=Franklin|first2=Kim|title=Shrikes and Bush-Shrikes|publisher=Princeton University Press|pages=257–260|isbn=978-0-691-07036-0|year=2000}}</ref> babblers such as [[Biology:Scimitar babbler|scimitar babbler]]s and some owls<ref>{{cite magazine|last=Osmaston|first=B. B.|year=1941|title=&thinsp;"Duetting" in birds|magazine=Ibis|volume=5| pages=310–311|doi=10.1111/j.1474-919X.1941.tb00620.x|issue= 2}}</ref> and parrots.<ref>{{cite magazine|last=Power|first=D. M.|year=1966|title=Antiphonal duetting and evidence for auditory reaction time in the Orange-chinned Parakeet|magazine=Auk|volume=83|issue= 2|pages=314–319|doi=10.2307/4083033|jstor=4083033}}</ref>}}

[[File:Balck Heron canopy crop.jpg|thumb|Black herons {{gli|canopy feeding}}.]]
{{Term|canopy feeding|content=canopy feeding {{anchor|canopy feeding|double-wing feeding|double wing feeding}} }}
{{defn|''Also defined: '''double-wing feeding'''.'' Some [[Biology:Heron|heron]]s, such as the [[Biology:Black heron|black heron]], adopt an unusual position while hunting for prey. With their head held down in a hunting position, they sweep their wings forward to meet in front of their head, thereby forming an umbrella shaped canopy. To achieve full canopy closure, the [[Biology:Flight feather#Primaries|primaries]] and [[Biology:Flight feather#Secondaries|secondaries]] touch the water, the [[Medicine:Nape|nape]] feathers are erected and the tail is drooped. The bird may take several strides in this position. One theory about the function of this behaviour is that it reduces glare from the water surface, allowing the bird to more easily locate and catch prey. Alternatively, the shade provided by the canopy may attract fish making their capture easier. Some herons adopt a similar behaviour called ''double-wing feeding'' in which the wings are swept forward to create an area of shade, though a canopy is not formed.<ref>{{cite book|last1=Hancock|first1=James|last2= Kushlan|first2=James|title=The Herons Handbook|publisher=A&C Black|year=2010|pages=20, 101–102|isbn=978-1-4081-3496-2| url=https://books.google.com/books?id=ldzxpcqepksC&pg=PT139|location=London}}</ref>}}

{{Term|carpal bar|content=carpal bar {{anchor|carpal-bar|carpal bars|carpal-bars}} }}
{{defn|A patch seen on the {{gli|upperwing}} of some birds that usually appears as a long stripe or line. It is created by the contrast between the greater coverts and the other wing feathers.<ref name="Floyd2008_495">{{Harvnb|Floyd|2008|p=495}}</ref>}}

{{Term|caruncle|content=caruncle {{anchor|caruncles|dewlap|dewlaps|ear lobe|er lobes|nodule|nodules}} }}
{{defn|The collective term for the several fleshy protuberances on the heads and throats of [[Biology:Galliformes|gallinaceous]] birds, i.e., {{gli|combs}}, {{gli|wattles}}, ear lobes and nodules. They can be present on the head, neck, {{gli|throat}}, {{gli|cheeks}} or around the eyes of some birds. Caruncles may be featherless, or present with a small array of scattered feathers. In some species, they may form pendulous structures of [[Biology:Erectile tissue|erectile tissue]], such as the "[[Biology:Snood (anatomy)|snood]]" of the [[Biology:Domestic turkey|domestic turkey]].<ref>{{cite book|title=Catalogue of the birds in the British Museum|publisher=British Natural History Museum Department of Zoology|last1=Sharpe|first1=Richard Bowdler|year=1888}}</ref><ref>{{cite book|title=The Birds of America|publisher=Dover Publications |last1=Audubon|first1=John James|last2=Amadon|first2=Dean|last3=Bull|first3=John L.|year=1967|oclc=555150}}</ref> While caruncles are ornamental elements used by males to attract females to breed,<ref name="Burke">{{cite book|url=https://books.google.com/books?id=MMMjW6AuzHAC&pg=PA702|title=The Complete Burke's Backyard: The Ultimate Book of Fact Sheets|last1=Burke|first1=Don|page=702|isbn=9781740457392|year=2005}}</ref> it has been proposed that these organs are also associated with genes that encode resistance to disease,<ref name="BarattiAmmannati2010">{{cite magazine|last1=Baratti|first1=Mariella|last2=Ammannati|first2=Martina|last3=Magnelli|first3=Claudia|last4=Massolo|first4=Alessandro|last5=Dessì-Fulgheri|first5=Francesco|title=Are large wattles related to particular MHC genotypes in the male pheasant?|magazine=Genetica|volume=138|issue= 6|year=2010|pages=657–665| issn=0016-6707|doi=10.1007/s10709-010-9440-5|pmid=20145977|s2cid=35053439}}</ref> and for birds living in tropical regions, that caruncles also play a role in thermoregulation by making the blood cool faster when flowing through them.<ref>{{cite magazine|magazine=The Auk|year=1996|last1=Buchholz|first1=Richard|url=https://sora.unm.edu/sites/default/files/journals/auk/v113n02/p0310-p0318.pdf|volume=113|issue= 2|pages=310–318|title=Thermoregulatory Role of the Unfeathered Head and Neck in Male Wild Turkeys|doi=10.2307/4088897|jstor=4088897}}</ref>}}

[[File:Aceros cassidix -Vogelpark Walsrode -pair-8a.jpg|thumb|upright=1.25|A pair of [[Biology:Knobbed hornbill|knobbed hornbill]]s with prominent {{gli|casques}} on display]]
{{Term|casque|content=casque {{anchor|casques}} }}
{{Main|Biology:Casque (anatomy)}}
{{defn|A horny ridge found on the {{gli|upper mandible}} of a bird's bill, especially used in relation to [[Biology:Hornbill|hornbill]]s and cassowaries,<ref name="Blake1977">{{cite book|last=Blake|first=Emmet Reid|title=Manual of Neotropical Birds|url=https://books.google.com/books?id=YP0AX3LW8jYC&pg=PA428|year=1977|publisher=University of Chicago Press|isbn=978-0-226-05641-8|page=428}}</ref><ref name="PrattBeehler2014">{{cite book|last1=Pratt|first1=Thane K.|last2=Beehler|first2=Bruce M.|title=Birds of New Guinea|url=https://books.google.com/books?id=SBn8AwAAQBAJ&pg=PA262|edition=2nd|year=2014|publisher=Princeton University Press|location=Oxford|isbn=978-1-4008-6511-6|page=262}}</ref> though other birds may have casques such as [[Biology:Common moorhen|common moorhen]]s,<ref name="ReillySociety1968">{{cite book|last1=Reilly|first1=Edgar M.|author2=National Audubon Society|title=The Audubon illustrated handbook of American birds|url=https://archive.org/details/audubonillustrat00reil|url-access=registration|year=1968|publisher=McGraw-Hill|page=[https://archive.org/details/audubonillustrat00reil/page/142 142]}}</ref> [[Biology:Tufted puffin|tufted puffin]]s<ref name="Stejneger1885">{{cite book|last=Stejneger|first=Leonhard Hess|title=Results of Ornithological Explorations in the Commander Islands and in Kamtschatka|url=https://archive.org/details/resultsornithol00stejgoog|year=1885|publisher=U.S. Government Printing Office|pages=[https://archive.org/details/resultsornithol00stejgoog/page/n61 52]–53}}</ref> and (male) friarbirds.<ref name="Harris226">{{cite book|author=National Geographic Society|editor-last1=Harris|editor-first1=Tim|title=Complete Birds of the World|url=https://books.google.com/books?id=0TIiIdLp9xkC&pg=PA226|year=2009|publisher=National Geographic|isbn=978-1-4262-0403-6|page=226}}</ref> The ridge line on the {{gli|upper maxilla}} may extend to a prominent crest on the front of the face and on the head, such as in the "flamboyant" crest of the [[Biology:Rhinoceros hornbill|rhinoceros hornbill]].<ref name="Mobley339">{{Harvnb|Mobley, et al.|2008|p=339}}</ref> Some hornbill casques contain a hollow space that may act as a [[Physics:Resonance chamber|resonance chamber]], amplifying {{gli|calls}}.<ref name="Carnaby124">{{Harvnb|Carnaby|2008|p=124}}</ref>  Similar function has been proposed for cassowary casques, as well as for protection of the head while dense vegetation is traversed, as a [[Biology:Biological ornament|sexual ornament]] and for use as a "shovel" for digging food.<ref name="Mobley441">{{Harvnb|Mobley, et al.|2008|p=441}}</ref> ''Compare: {{gli|frontal shield}}''.}}

{{Term|cere|content=cere {{anchor|ceres}} }}
{{defn|From the Latin ''cera'' meaning 'wax', a waxy structure which covers the base of the {{gli|bills}} of some bird species from a handful of families—including [[Biology:Bird of prey|raptors]], [[Biology:Owl|owl]]s, skuas, [[Biology:Parrot|parrot]]s, [[Biology:Turkey (bird)|turkey]]s and curassows. The cere structure typically contains the {{gli|nares}}, except in owls, where the nares are distal to the cere. Although it is sometimes feathered in parrots,<ref>{{cite book|first1=Tony |last1=Jupiter|first2=Mike|last2=Parr|page=17|title=Parrots: A Guide to Parrots of the World|url=https://books.google.com/books?id=kqYmmbZXlOkC|year=2010|publisher=A&C Black|isbn=978-1-4081-3575-4}}</ref> the cere is typically bare and often brightly coloured.<ref name="Stettenheim"/> In raptors, the cere is a sexual signal which indicates the "quality" of a bird; the orangeness of a Montague's harrier's cere, for example, correlates to its body mass and physical condition.<ref name="Mougeo">{{cite magazine|magazine=Biology Letters|first1=François|last1=Mougeo|first2=Beatriz E.|last2=Arroyo|title=Ultraviolet reflectance by the cere of raptors |date=June 22, 2006|volume=2|issue= 2|pages=173–176|doi=10.1098/rsbl.2005.0434 |pmid=17148356|pmc=1618910}}</ref> The colour or appearance of the cere can be used to distinguish between males and females in some species. For example, the male [[Biology:Great curassow|great curassow]] has a yellow cere, which the female (and young males) lack,<ref>{{cite book |title=Wildlife of Mexico: The Game Birds and Mammals|publisher=University of California Press|isbn=978-0-520-00724-6|year=1972|page=[https://archive.org/details/wildlifeofmexico00leop/page/202 202]|first=Aldo Starker|last=Leopold|location=Berkeley, CA|url=https://archive.org/details/wildlifeofmexico00leop/page/202}}</ref> and the male [[Biology:Budgerigar|budgerigar]]'s cere is blue, while the female's is pinkish or brown.<ref>{{cite book |title=A Birdkeeper's Guide to Budgies |first= David |last=Alderton |year=1996 |publisher=Tetra Press | page=12}}</ref>}}

{{Term|cheek|content=cheek {{anchor|malar|malars|cheeks|malar region}} }}
{{defn|''Also, '''malar'''&thinsp;/&thinsp;'''malar region'''.'' The area of the sides of a bird's head, behind and below the eyes.<ref name="Pettingill9"/>}}

{{Term|chin|content=chin {{anchor|chins}} }}
{{defn|A small feathered area located just below the base of the {{gli|bill}}'s {{gli|lower mandible}}.<ref name="Vinicombe14">{{Harvnb|Vinicombe|2014|p=14}}</ref>}}

{{Term|cloaca|content=cloaca {{anchor|cloacas|cloacae}} }}
{{defn|A multi-purpose opening terminating at the {{gli|vent}} at the posterior of a bird: birds expel waste from it; most birds mate by [[Biology:Bird anatomy#Reproduction|joining cloaca]] (a "{{gli|cloacal kiss}}"); and females lay eggs from it. Birds do not have a [[Biology:Urinary bladder|urinary bladder]] or external urethral opening and (with exception of the [[Biology:Ostrich#Description|ostrich]]) uric acid is excreted from the cloaca, along with faeces, as a semisolid waste.<ref>{{cite web|last1=Ehrlich |first1=Paul R. |last2=Dobkin|first2=David S. |last3=Wheye|first3=Darryl|title=Drinking |url=http://www.stanford.edu/group/stanfordbirds/text/essays/Drinking.html |year=1988 |work=Birds of Stanford |publisher=Stanford University |access-date=January 29, 2017}}</ref><ref>{{cite magazine|last1=Tsahar|first1=Ella|title=Can birds be ammonotelic? Nitrogen balance and excretion in two frugivores|magazine=Journal of Experimental Biology|volume=208|issue= 6|pages=1,025–34|year=2005|pmid=15767304 |doi=10.1242/jeb.01495 |last2=Martínez Del Rio|first2=C.|last3=Izhaki|first3=I.|last4=Arad |first4=Z.|doi-access=free}}</ref><ref name=coprodeum>{{cite journal|doi= 10.1016/S1095-6433(03)00006-0|last1= Skadhauge|first1= E.|last2=Erlwanger|first2=K.H.|last3= Ruziwa|first3=S.D.|last4=Dantzer|first4=V. |last5=Elbrønd| first5=V.S.|last6=Chamunorwa|first6=J.P.|title=Does the ostrich (''Struthio camelus'') coprodeum have the electrophysiological properties and microstructure of other birds?|journal= Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology|magazine= |volume=134|issue= 4|pages=749–755|year= 2003 |pmid=12814783 }}</ref> Additionally, in those few bird species in which males possess a penis ([[Biology:Palaeognathae|Palaeognathae]] [with the exception of the [[Biology:Kiwi (bird)|kiwi]]s], the [[Biology:Anseriformes|Anseriformes]] [with the exception of [[Biology:Screamer|screamer]]s] and in rudimentary forms in [[Biology:Galliformes|Galliformes]]<ref>{{cite web|last=Yong |first=Ed |url=http://phenomena.nationalgeographic.com/2013/06/06/how-chickens-lost-their-penises-ducks-kept-theirs/ |archive-url=https://web.archive.org/web/20130609052803/http://phenomena.nationalgeographic.com/2013/06/06/how-chickens-lost-their-penises-ducks-kept-theirs/ |url-status=dead |archive-date=June 9, 2013 |title=Phenomena: Not Exactly Rocket Science How Chickens Lost Their Penises (And Ducks Kept Theirs) |date=6 June 2013 |publisher=Phenomena.nationalgeographic.com |access-date=January 29, 2017}}</ref><ref>{{cite web |url=http://bcs.whfreeman.com/gill/bcs-pages/body-right_10.asp?s=10000&n=00010&i=99010.06&v=chapter&o=%7C13000%7C00010%7C&ns=undefined |title=Ornithology, 3rd Edition – Waterfowl: Order Anseriformes |access-date=January 29, 2017 |url-status=dead |archive-url=https://web.archive.org/web/20150622030534/http://bcs.whfreeman.com/gill/bcs-pages/body-right_10.asp?s=10000&n=00010&i=99010.06&v=chapter&o=%7C13000%7C00010%7C&ns=undefined |archive-date=June 22, 2015 }}</ref>) it is hidden within the proctodeum compartment within the cloaca, just inside the vent.<ref name="Pettingill376">{{Harvnb|Pettingill|1985|p=376}}</ref>}}

{{Term|cloacal kiss|content=cloacal kiss {{anchor|cloacal contact}} }}
{{defn|Most male birds lack a phallus and instead have erectile [[Biology:Genital papilla|genital papilla]] at the terminus of their vas deferens. When male and female birds of such species copulate, they each evert and then press together, or "kiss" their respective proctodeum (the lip of the cloaca). Upon the clocal kiss, the male's sperm spurts into the female's urodoeum (a compartment inside the {{gli|cloaca}}), which then make their way into the oviduct.<ref name="Maxwell2013">{{cite book|last=Maxwell|first=Kenneth E.|title=The Sex Imperative: An Evolutionary Tale of Sexual Survival|url=https://books.google.com/books?id=dnf1BwAAQBAJ&pg=PA99|year=2013|publisher=Springer|isbn=978-1-4899-5988-1|page=99}}</ref><ref name="Doneley2016">{{cite book|last=Doneley|first=Bob|title=Avian Medicine and Surgery in Practice: Companion and Aviary Birds, Second Edition|url=https://books.google.com/books?id=xQrYCwAAQBAJ&pg=PA12|year=2016|publisher=CRC Press|isbn=978-1-4822-6019-9|page=12}}</ref>}}

{{Term|clutch|content=clutch {{anchor|clutches}} }}
{{main|Biology:Clutch (eggs)}}
{{defn|All of the eggs produced by birds often at a single time in a {{gli|nest}}. Clutch size differs greatly between species, sometimes even within the same [[Biology:Genus|genus]]. It may also differ intraspecies due to many factors including habitat, health, nutrition, predation pressures and time of year.<ref>{{cite magazine|magazine=The Ibis|last1=Lack|first1=David|year=1947|pages=302–352|title=The significance of clutch-size (part I-II)|volume=89|issue= 2|url=https://books.google.com/books?id=TaYfZBU11ZoC|orig-date=1887|doi=10.1111/j.1474-919X.1947.tb04155.x}}</ref> Average clutch size ranges from one (as in northern gannet<ref name="Pettingill310">{{Harvnb|Pettingill|1985|p=310}}</ref>) to about 17 (as in [[Biology:Grey partridge|grey partridge]]<ref name="McCabe1943">{{cite book|last=McCabe|first=Robert A.|title=Hungarian partridge (perdix perdix linn.) studies in Wisconsin|url=https://books.google.com/books?id=Vkc7AAAAMAAJ|year=1943|publisher=University of Wisconsin—Madison|page=28}}</ref>).}}

[[File:Rooster portrait2.jpg|upright=0.8|thumb|A rooster with a large red {{gli|comb}}]]
{{Term|comb|content=comb {{anchor|coxcomb|combs|coxcombs}} }}
{{Main|Biology:Comb (anatomy)}}
{{defn|''Also, '''cockscomb''' ('''coxcomb''' and other sp. variants).'' A fleshy growth or crest on the top of the head of [[Biology:Galliformes|gallinaceous]] birds, such as [[Biology:Domestic turkey|turkeys]], [[Biology:Pheasant|pheasant]]s and domestic [[Biology:Chicken|chicken]]s. Its alternative name, cockscomb (or coxcomb) reflects that combs are generally larger on males than on females (a male gallinaceous bird is called a cock). Comb shape varies considerably depending on the breed or species of bird. The "comb" most often refers to chickens in which the most common shape is the "single comb" of a rooster from breeds such as the leghorn. Other common comb types are the "rose comb" of, e.g., the eponymous [[Biology:Rosecomb|rosecomb]]; the "pea comb" of, e.g., the brahma and araucana; and others.<ref>{{cite magazine|last=Anderson|first=Dave|magazine=Backyard Poultry Magazine|title=The Chicken's Comb|date=February–March 2008}}</ref>}}

{{Term|colony|content=colony {{anchor|colonies|colonial|seabird colony|seabird colonies|breeding colony|breeding colonies|communal roost|communal roosts|communal roosting|heronries|heronry|rookery|rookeries}} }}
{{defn|''Also defined: '''seabird colony'''; '''breeding colony'''; '''communal roost'''; '''heronries'''; '''rookery'''.'' A large congregation of individuals of one or more species of bird that nest or roost in proximity at a particular location. Many kinds of birds are known to congregate in groups of varying size; a congregation of nesting birds is called a ''breeding colony''. A group of birds congregating for rest is called a ''[[Earth:Communal roosting|communal roost]]''. Approximately 13% of all bird species nest colonially.<ref name="Gill138–141">{{Harvnb|Gill|1995|pp=138–141 }}</ref> Nesting colonies are very common among seabirds on cliffs and islands. Nearly 95% of seabirds are colonial,<ref>{{cite magazine|doi=10.1016/S0169-5347(97)01124-5|pmid=21238100|last1=Danchin|first1=E.|last2=Wagner|first2=R.H.|title=The evolution of coloniality: the emergence of new perspectives|magazine=Trends in Ecology and Evolution|volume=12|issue=2|pages=342–347|year=1997|url=http://www.univet.hu/users/jkis/education/Visokol/Coloniality.pdf|access-date=2017-04-01|archive-date=2011-10-03|archive-url=https://web.archive.org/web/20111003160047/http://www.univet.hu/users/jkis/education/Visokol/Coloniality.pdf|url-status=dead}}</ref> leading to the usage, ''seabird colony'', sometimes called a ''[[Biology:Rookery|rookery]]''. Many species of [[Biology:Tern|tern]]s nest in colonies on the ground. [[Biology:Heron|Heron]]s, [[Biology:Egret|egret]]s, [[Biology:Stork|stork]]s and other large waterfowl also nest communally in what are called ''heronries''. Colony nesting may be an evolutionary response to a shortage of safe nesting sites and abundance or unpredictable food sources which are far away from the nest sites.<ref name="Roll">{{cite magazine|doi=10.1086/286137|last1=Rolland|first1=Cecile|last2=Danchin|first2=Etienne|last3=de Fraipont|first3=Michelle|title=The Evolution of Coloniality in Birds in Relation to Food, Habitat, Predation, and Life-History Traits: A Comparative Analysis|magazine=The American Naturalist|volume=151|issue= 6|pages=514–529|year=1998|url=http://www.biosci.missouri.edu/avianecology/courses/avianecology/readings/Rolland_C_1998.pdf|pmid=18811373|url-status=dead|archive-url=https://web.archive.org/web/20100620170547/http://www.biosci.missouri.edu/avianecology/courses/avianecology/readings/Rolland_C_1998.pdf|archive-date=June 20, 2010}}</ref>}}

{{Term|colour morph}}
{{defn|''See {{gli|morph}}.''}}

{{Term|commissure}}
{{defn|Depending on usage, may refer to the junction of the {{gli|upper mandible|upper}} and {{gli|lower mandible|lower}} mandibles,<ref>{{Harvnb|Coues|1890|p=155}}</ref> or alternately, to the full-length apposition of the closed mandibles, from the corners of the mouth to the tip of the {{gli|beak}}.<ref>{{Harvnb|Campbell|Lack|1985|p=105}}</ref>}}

{{Term|contact call|content=contact call {{anchor|contact calls}} }}
{{defn|A type of {{gli|call}} used by birds for the purpose of letting others of their species know their location.<ref name="Weaver34">{{Harvnb|Weaver|1981|p=34}}</ref>}}

{{Term|corpuscles of Herbst|content=corpuscles of Herbst {{anchor|corpuscle of Herbst|Herbst corpuscle|Herbst corpuscles}} }}
{{defn|Nerve-endings similar to the [[Biology:Pacinian corpuscle|Pacinian corpuscle]], found in the [[Biology:Mucous membrane|mucous membrane]] of the [[Biology:Tongue|tongue]], in pits on the beak and in other parts of the bodies of birds. They differ from Pacinian corpuscles in being smaller and more elongated, in having thinner and more closely placed capsules and in that the axis-cylinder in the central clear space is encircled by a continuous row of [[Biology:Cell nucleus|nuclei]].<ref name="Klein1785">{{cite book|last1=Klein|first1=Edward |title=Elements of Histology|url=https://archive.org/details/elementshistolo02kleigoog|place=Philadelphia|year=1785|publisher=Lea|page=[https://archive.org/details/elementshistolo02kleigoog/page/n140 124]}}</ref>}}

{{Term|coverts|content=coverts {{anchor|covert|covert feather|covert feathers|tectrices|tectrice|tectrix}} }}
{{defn|''Also, '''covert feathers'''; '''tectrices''' – singular: '''tectrix'''.'' A layer of non-flight feathers overlaying and protecting the {{gli|quills}} of flight feathers. At least one layer of covert feathers appear both above and beneath the {{gli|flight feathers}} of the wings as well as above and below the {{gli|rectrices}} of the tail.<ref name="Pierce">{{cite book|last1=Pierce|first1=R.M.|title=Dictionary of aviation|url=https://books.google.com/books?id=L84PAwAAQBAJ&pg=PA69|publisher=Рипол Классик|isbn=978-5-87745-565-8|pages=69–70|year=1911}}</ref> These feathers may vary widely in size. For example, the upper tail tectrices of peacocks—the male [[Biology:Peafowl|peafowl]]—rather than its rectrices, are what constitute its elaborate and colourful "train".<ref name="Mobley295">{{Harvnb|Mobley, et al.|2008|p=295}}</ref> There are a number of types and subtypes of covert feathers—primary, secondary, greater, lesser, marginal, median, etc.—''see broadly {{gli|wing coverts}} and {{gli|tail coverts}}''.}}

{{Term|cranial kinesis|content=cranial kinesis {{anchor|prokinesis|amphikinesis|distal rhynchokinesis}} }}
{{defn|''Also defined: '''prokinesis''', '''amphikinesis''' and '''distal rhynchokinesis'''.'' Movement of the {{gli|upper mandible}} in relation to the front of the skull. There is very little of this movement in birds that feed primarily through grazing and thus do not need to open their bills very widely. This is in contrast to parrots, which use their bills to manipulate food and as a support when climbing trees. There are multiple types of cranial kinesis: ''prokinesis'', where the bill moves only at the craniofacial hinge; ''amphikinesis'', where the whole upper jaw is raised; and ''distal rhynchokinesis'', where the bill flexes somewhere along the length of the bill, compared to just at the base.<ref name="Elphick2016-22-23">{{Harvnb|Elphick|2016|pp=22–23}}</ref>}}

[[File:Umbrella Cockatoo (Cacatua alba) -Free Flight Aviary -San Diego.jpg|thumb|upright=0.8|A white cockatoo, also called the ''umbrella cockatoo'' from the shape of its {{gli|crest}}]]
{{Term|crest feather|content=crest feather {{anchor|crest|crests|crest feathers|recumbent crest|recursive crest|recumbent crests|recursive crests|quill feather|quill feathers}} }}
{{defn|''Collectively, the/a '''crest'''. Long crest feathers are sometimes called '''quill feathers'''.<ref name="Carnaby10">{{Harvnb|Carnaby|2008|p=10}}</ref> Also defined: '''recumbent crests''' and '''recursive crests'''.'' A type of {{gli|semiplume}} feather with a long {{gli|rachis}} with {{gli|barbs}} on either side, that often presents as a prominent tuft on the {{gli|crown}} and (or through) the neck and upper {{gli|back}}.<ref>{{cite magazine|magazine=Bulletin of the British Ornithologists' Club|last=Tye|first=Hilary|volume=106|issue= 3|title=The erectile crest and other head feathering in the genus Picathartes|page=91|date=December 1985|url=https://www.biodiversitylibrary.org/item/123887#page/499/mode/1up}}</ref><ref name="Proctor64"/> Birds with crests include Victoria crowned pigeons, [[Biology:Northern lapwing|northern lapwing]]s, [[Biology:Macaroni penguin|macaroni penguin]]s and others, but the most recognizable are cockatoos and cockatiels, which can raise or lower their crests at will and use them to communicate with fellow members of their species, or as a form of defence to frighten away other species that approach too closely, making the bird appear larger when the crest is suddenly and unexpectedly raised.<ref name="Highfill">{{cite web|last=Highfill|first=Carol|title=Those Magnificent Cockatoo Crests|url=http://www.birdsnways.com/cockatoo/crests.htm|publisher=Cockatoo Heaven|access-date=March 23, 2017|archive-url=https://web.archive.org/web/20170301234333/http://www.birdsnways.com/cockatoo/crests.htm|archive-date=March 1, 2017|url-status=dead}}</ref> In some species the position of the crest is a threat signal that can be used to predict behaviour. In [[Biology:Steller's jay|Steller's jay]]s, for example, a raised crest indicates a likelihood of attack, and a lowered crest indicates a likelihood of retreat.<ref name="Gill318–319">{{Harvnb|Gill|1995|pp=318–319}}</ref> Crests can be ''recumbent'' or ''recursive'', depending on the species. The recumbent crest, such as in [[Biology:White cockatoo|white cockatoo]]s, has feathers that are straight and lie down essentially flat on the head until fanned out.<ref>{{cite book|last=Moustaki|first=Nikki|title=Parrots for Dummies|year=2005|publisher=Wiley|location=Indianapolis, IN |isbn=978-0764583537|edition=1st}}</ref> The recursive crest, such as in [[Biology:Sulphur-crested cockatoo|sulphur-crested cockatoo]]s and Major Mitchell's cockatoos, is noticeable even when its feathers are not fanned out because they curve upward at the tips even when lying flat, and when standing up, often bend slightly forward toward the front of the head. Some birds, like [[Biology:Galah|galah]]s (also known as the rose-breasted cockatoo), have modified crests that have both recumbent and recursive features.<ref name="Highfill" />}}

[[File:Grey Catbird.jpg|thumb|upright=0.8|A grey catbird, with its distinctly coloured {{gli|crissum}} on display]]
{{Term|crissum|content=crissum}}
{{defn|The feathered area between the {{gli|vent}} and the {{gli|tail}}. Also, the collective name for the {{gli|undertail coverts}}.<ref name="Pettingill21">{{Harvnb|Pettingill|1985|p=21}}</ref> The [[Biology:Crissal thrasher|crissal thrasher]] derives its name from the term, having distinctive colouring in the region, in contrast with the balance of its {{gli|plumage}}. Other birds having distinctive crissum colouration include Le Conte's thrashers and grey catbirds.<ref name="Burns2008">{{cite book|last=Burns|first=Jim|title=Jim Burns' Arizona Birds: From the Backyard to the Backwoods|url=https://books.google.com/books?id=fFUNsToqnFMC&pg=PA166|year=2008|publisher=University of Arizona Press|isbn=978-0-8165-2644-4|page=166}}</ref>}}

{{Term|crop|content=crop {{anchor|crops}} }}
{{defn|An expanded, muscular pouch near the gullet or throat found in some but not all birds. It is a part of the digestive tract, essentially an enlarged part of the [[Biology:Esophagus|esophagus]], used for the storage of food prior to digestion. As with most other organisms that have a crop, birds use it to temporarily store food. In adult doves and pigeons, the crop can produce {{gli|crop milk}} to feed newly-hatched chicks.<ref>{{cite web|title=The Alimentary Canal in Birds|url=http://www.earthlife.net/birds/digestion.html|last1=Ramel|first1=Gordon|date=September 29, 2008|access-date=January 16, 2017|archive-url=https://web.archive.org/web/20170201223304/http://www.earthlife.net/birds/digestion.html|archive-date=February 1, 2017|url-status=dead}}</ref>}}

[[File:Rosaflamingo-Küken - Fuetterung mit Kropfmilch.jpg|thumb|upright=0.8|A [[Biology:Greater flamingo|greater flamingo]] chick being fed {{gli|crop milk}}]]
{{Term|crop milk}}
{{Main|Biology:Crop milk}}
{{defn|A secretion from the lining of the {{gli|crop}} of parent birds that is regurgitated to young birds. It is found among all [[Biology:Columbidae|pigeons and doves]] where it is referred to as {{gli|pigeon milk}}. An analogue to crop milk is also secreted from the esophagus of [[Biology:Flamingo#Feeding|flamingos]] and some [[Biology:Penguin|penguin]]s.<ref name="Levi">{{cite book |last=Levi |first=Wendell |title= The Pigeon|year= 1977|publisher= Levi Publishing Co, Inc|location= Sumter, S.C.|isbn=978-0-85390-013-9 }}</ref><ref name="Prolactin">{{cite magazine|last=Silver|first=Rae|title=Prolactin and Parenting in the Pigeon Family|magazine=The Journal of Experimental Zoology|volume=232|pages=617–625|year=1984|url=http://www.columbiauniversity.org/cu/psychology/silver/publications/035Silver%201984.PDF|doi=10.1002/jez.1402320330|pmid=6394702|issue= 3|url-status=bot: unknown|archive-url=https://web.archive.org/web/20160913135843/http://www.columbiauniversity.org/cu/psychology/silver/publications/035Silver%201984.PDF|archive-date=September 13, 2016}}</ref><ref>{{cite magazine|last1=Eraud|first1=C.|last2=Dorie|first2=A.|last3=Jacquet|first3=A.|last4=Faivre|first4=B.|year=2008| title= The crop milk: a potential new route for carotenoid-mediated parental effects| magazine=Journal of Avian Biology| volume=39| pages=247–251| doi=10.1111/j.0908-8857.2008.04053.x| issue= 2}}</ref> Crop milk bears little physical resemblance to [[Biology:Mammal|mammal]]ian milk, the former being a semi-solid substance somewhat like pale yellow cottage cheese. It is extremely high in [[Biology:Protein|protein]] and [[Chemistry:Fat|fat]], containing higher levels than cow or human milk<ref>Ehrlich, Paul R.; Dobkin, David S. and Wheye, Darryl (1988) [http://www.stanford.edu/group/stanfordbirds/text/essays/Bird_Milk.html Bird Milk]. stanford.edu</ref> and has been shown to also contain antioxidants and immune-enhancing factors.<ref>{{cite web|url=http://www.australiangeographic.com.au/journal/birds-produce-milk-similar-to-mammals.htm|title=Mysteries of pigeon milk explained|access-date=August 17, 2017|url-status=dead|archive-url=https://web.archive.org/web/20130814213943/http://www.australiangeographic.com.au/journal/birds-produce-milk-similar-to-mammals.htm|last=Phillips|first=Campbelll|date=September 22, 2011|archive-date=August 14, 2013|publisher=Australian Geographic}}</ref>}}

{{Term|crown|content=crown {{anchor|crowns|occiput|hindhead}} }}
{{defn|''Also defined: '''occiput'''&thinsp;/&thinsp;'''hindhead'''.'' The portion of a bird's head found between the {{gli|forehead}}—demarcated by an imaginary line drawn from the anterior corners of the eyes—and through the "remainder of the upper part of the head", to the {{gli|superciliary line}}.  The ''occiput'' or ''hindhead'', is the posterior part of the crown.<ref name="Pettingill10">{{Harvnb|Pettingill|1985|p=10}}</ref>}}

{{Term|cryptic plumage|content=cryptic plumage {{anchor|cryptic plumages|cryptic|phaneric plumage|phaneric plumages|phaneric}} }}
{{defn|''Also defined: '''phaneric plumage'''.'' Plumage of a bird that is camouflaging. For example, the white winter plumage of [[Biology:Lagopus|ptarmigans]] is cryptic as it serves to conceal it in snowy environments.<ref name="Gill1106">{{Harvnb|Gill|1995|p=106}}</ref> The opposite, "advertising" plumage, is termed "phaneric", such as male birds in colourful {{gli|nuptial plumage}} for sexual display, making them stand out to a high degree.<ref name="Ryser1985">{{cite book|last=Ryser|first=Fred A.|title=Birds of the Great Basin: A Natural History|url=https://books.google.com/books?id=bxpXq_hMxfAC&pg=PA22|year=1985|publisher=University of Nevada Press|isbn=978-0-87417-080-1|page=22}}</ref>}}

{{Term|culmen}}
{{defn|The dorsal ridge of the {{gli|upper mandible}}.<ref>{{Harvnb|Campbell|Lack|1985|p=127}}</ref> Likened by ornithologist [[Biography:Elliott Coues|Elliott Coues]] to the ridge line of a roof, it is the "highest middle lengthwise line of the bill" and runs from the point where the upper mandible emerges from the forehead's feathers to its tip.<ref>{{Harvnb|Coues|1890|p=152}}</ref> The {{gli|bill}}'s length along the culmen is one of the regular measurements made during bird ringing<ref name="Pyle">{{cite book |title=Identification Guide to North America Passerines |first1=Peter|last1=Pyle|first2=Steve N. G.|last2=Howell|first3=Robert P.|last3=Yunick|first4=David F. |last4=DeSante|publisher=Slate Creek Press|location=Bolinas, CA|year=1987|isbn=978-0-9618940-0-9|pages=6–7}}</ref> and is particularly useful in feeding studies.<ref name="Borras">{{cite magazine|title=What Do Different Bill Measures Measure and What Is the Best Method to Use in Granivorous Birds?|url=http://www.bcn.cat/museuciencies_fitxers/imatges/FitxerContingut1987.pdf |first1=A.|last1=Borras |first2= J. |last2=Pascual|first3=J. C.|last3=Senar |magazine=Journal of Field Ornithology |volume=71|issue= 4|date=Autumn 2000|pages=606–611|jstor=4514529|doi=10.1648/0273-8570-71.4.606 }}</ref> The shape or colour of the culmen can also help with the identification of birds in the field. For example, the culmen of the [[Biology:Parrot crossbill|parrot crossbill]] is strongly decurved, while that of the very similar appearing [[Biology:Red crossbill|red crossbill]] is more moderately curved.<ref>{{cite book|title=Collins Bird Guide: The Most Complete Field Guide to the Birds of Britain and Europe |first1=Killian|last1=Mullarney|first2=Lars|last2=Svensson |first3=Dan|last3=Zetterström|first4=Peter J.|last4=Grant|year=1999|publisher=Harper Collins |location=London|isbn=978-0-00-711332-3|page=357}}</ref>}}

{{Glossary end}}

==D==
{{Glossary}}
{{Term|definitive plumage|content=definitive plumage {{anchor|definitive plumages|adult plumage|adult plumages}} }}
{{defn|Adult [[Biology:Plumage|plumage]] sufficiently developed and fixed following the juvenile years such that it no longer changes significantly in appearance with age.<ref name="Pettingill189-192"/>}}

{{Term|diastataxis}}
{{defn|The state of lacking a fifth {{gli|secondary feather}} on each wing, which occurs in birds in more than 40 non-passerine families. In these birds, the fifth set of secondary covert feathers does not cover any {{gli|remex}}. [[Biology:Loon|Loon]]s, [[Biology:Grebe|grebe]]s, [[Biology:Pelican|pelican]]s, [[Biology:Hawk|hawk]]s and [[Biology:Eagle|eagle]]s, [[Biology:Crane (bird)|cranes]], [[Biology:Sandpiper|sandpiper]]s, [[Biology:Gull|gull]]s, [[Biology:Parrot|parrot]]s and [[Biology:Owl|owl]]s are among the families missing this feather.<ref name="Campbell656">{{Harvnb|Campbell|Lack|1985|p=656}}</ref>}}

{{Term|dietary classification terms (-vores)|content=dietary classification terms (-vores) {{anchor|insectivore|insectivores|insectivorous|carnivore|carnivores|carnivorous|faunivore|faunivores|faunivorous|folivore|folivores|folivorous|crustacivores|crustacivores|crustacivorous|nectarivore|nectarivores|nectarivorous|frugivore|frugivores|frugivorous|granivore|granivores|granivorous|omnivore|omnivores|omnivorous|general feeders|piscivore|piscivores|piscivorous|florivore|florivores|florivorous|folivore|folivores|folivorous|sanguinivore|sanguinivores|sanguinivorous|saprovore|saprovores|saprovorous|herbivore|herbivores|herbivorous|detritivore|detritivores|detritivorous}} }}
{{defn|Birds may be classified by terms related to the types of foods they forage for and eat.<ref name="Carnaby334">{{Harvnb|Carnaby|2008|p=334}}</ref> The -vore suffix is derived from the Latin ''vorare'', meaning 'to devour'. Equivalent adjectives can be formed through use of the suffix -vorous.<ref>{{cite book|last=Molles|first=Manuel C. Jr. |title=Ecology: Concepts and Applications|url=https://archive.org/details/ecologyconceptsa0000moll_j9m2|url-access=registration|publisher=McGraw-Hill|edition=International |year=1999|location=Dubuque|page=[https://archive.org/details/ecologyconceptsa0000moll_j9m2/page/510 510]|isbn=978-0-07-042716-7}}</ref> For example, ''granivore'' (n.) / ''granivorous'' (adj.). Generally, classification terms are used based on predominance of food source and/or specialization. There can be much cross-over and mixing between classifications. For example, insectivores and piscivores may at times be described more broadly as types of carnivores, and hummingbirds, though they do eat insects, are often described as nectarivores, rather than insectivores, as nectar is a specialized and predominant food foraging source for that bird family.<ref name="HoseyMelfi2013">{{cite book|last1=Hosey|first1=Geoff |last2=Melfi|first2=Vicky |author3=Sheila Pankhurst|title=Zoo Animals: Behaviour, Management, and Welfare|url=https://books.google.com/books?id=Ua2cAQAAQBAJ&pg=PA419|year=2013|publisher=OUP Oxford|isbn=978-0-19-969352-8|page=419}}</ref> The feeding strategies of birds is intimately tied to their physiology and evolutionary development. For example, {{gli|beak}} shape and structure such as the makeup of the {{gli|tomia}}, the presence (or not) of a {{gli|bill tip organ}} and myriad other adaptations are tied to a species' feeding strategies.<ref name="Scanes2014">{{cite book|last=Scanes|first=Colin G.|title=Sturkie's Avian Physiology|url=https://books.google.com/books?id=wgN0AwAAQBAJ&pg=PA61|year=2014|publisher=Elsevier Science|isbn=978-0-12-407243-5|page=61}}</ref> Feeding habits also correlate with aspects of brain development and size. For example, the [[Physics:Spatial memory|spatial memory]] of birds that store food in various locations has been shown to be highly developed and contributes towards success at that feeding tactic.<ref name="AdamsPedersen2000">{{cite book|last1=Adams|first1=Rick A.|last2=Pedersen|first2=Scott C.|title=Ontogeny, Functional Ecology, and Evolution of Bats|url=https://books.google.com/books?id=W61Cjl6xJvsC&pg=PA124|year=2000|publisher=Cambridge University Press|isbn=978-1-139-42949-8|page=124}}</ref>}}
:{| border="1"
|-
|'''[[Biology:Carnivore|carnivores]]''' (sometimes called '''''faunivores'''''): birds that predominantly forage for the meat of vertebrates—generally hunters as in certain birds of prey—including [[Biology:Eagle|eagle]]s, [[Biology:Owl|owl]]s and [[Biology:Shrike|shrike]]s, though piscivores, insectivores and crustacivores may be called specialized types of carnivores.<ref name="IrwinStoner2013">{{cite book|last1= Irwin|first1=Mark D.|last2=Stoner|first2=John B.|last3=Cobaugh|first3=Aaron M.|title=Zookeeping: An Introduction to the Science and Technology|url=https://books.google.com/books?id=Q7TbAgAAQBAJ&pg=PA166|year=2013|publisher=University of Chicago Press|isbn=978-0-226-92532-5|page=166}}</ref>
|-
|'''crustacivores''': birds that forage for and eat [[Biology:Crustacean|crustacean]]s, such as [[Biology:Crab-plover|crab-plover]]s and some [[Biology:Rallidae|rails]].<ref name="IrwinStoner2013"/>
|-
|'''[[Biology:Detritivore|detritivores]]''': birds that forage for and eat decomposing material, such as [[Biology:Vulture|vulture]]s. It is usually used as a more general term than "saprovore" (''defined below''), which often connotes the eating of decaying flesh alone.<ref name="Moore2009">{{cite book|last=Moore|first=Peter D.|title=Tropical Forests|url=https://books.google.com/books?id=yBG_7PHGvQ4C&pg=PA164|date=January 1, 2009|publisher=Infobase Publishing|isbn=978-1-4381-1874-1|page=164}}</ref>
|-
|'''florivores''': birds that forage for and eat plant material in general. Other terms for plant foraging specialization may apply to florivorous species, such as "frugivore" and "granivore".<ref name="Klasing1998">{{cite book|last=Klasing|first=Kirk C.|title=Comparative avian nutrition|url=https://books.google.com/books?id=76rwAAAAMAAJ|date=May 21, 1998|publisher=Cab International|isbn=978-0-85199-219-8|page=3}}</ref>
|-
|'''folivores''': birds that forage for and eat leaves, such as [[Biology:Hoatzin|hoatzin]] and [[Biology:Mousebird|mousebird]]s.<ref name="Carnaby334"/><ref name="IrwinStoner2013"/>
|-
|'''frugivores''': birds that forage for and eat fruit, such as [[Biology:Turaco|turaco]]s, [[Biology:Tanager|tanager]]s and [[Biology:Bird-of-paradise|birds-of-paradise]].<ref name="IrwinStoner2013"/>
|-
|'''granivores''': (sometimes called '''''seed-eating'''''): birds that forage for seeds and grains,<ref name="Swan1848">{{cite book|last=Swan|first=William Draper|title=The Instructive Reader, Or, A Course of Reading in Natural History, Science and Literature: Designed for the Use of Schools|url=https://books.google.com/books?id=EMpMAQAAMAAJ&pg=PA71|year=1848|publisher=Thomas, Cowperthwait|page=71}}</ref> such as geese, [[Biology:Grouse|grouse]] and [[Biology:Estrildid finch|estrildid finch]]es.<ref name="Carnaby334"/><ref name="IrwinStoner2013"/>
|-
|'''[[Earth:Herbivore|herbivore]]''': birds that predominantly eat plant material, and mostly do not eat meat; especially of birds that are both granivorous and frugivorous or are grass eaters, such as [[Biology:Whistling duck|whistling duck]]s, [[Biology:Ostrich|ostrich]]es and [[Biology:Mute swan|mute swan]]s.<ref name="IrwinStoner2013"/><ref name="Newton1998">{{cite book|last=Newton|first=Ian |title=Population Limitation in Birds|url=https://archive.org/details/populationlimita0000newt|url-access=registration|year=1998|publisher=Academic Press|isbn=978-0-08-087923-9|page=[https://archive.org/details/populationlimita0000newt/page/341 341]}}</ref>
|-
|'''[[Biology:Insectivore|insectivores]]''': birds that forage for and eat insects and other arthropods, such as [[Biology:Cuckoo|cuckoo]]s, [[Biology:Swallow|swallow]]s, [[Biology:Thrush (bird)|thrushes]], [[Biology:Drongo|drongo]]s and [[Biology:Woodpecker|woodpecker]]s.<ref name="Carnaby334"/><ref name="IrwinStoner2013"/>
|-
|'''nectarivores''': birds that drink the [[Biology:Nectar|nectar]] of flowers, such as [[Biology:Hummingbird|hummingbird]]s, [[Biology:Sunbird|sunbird]]s and lorikeets.<ref name="IrwinStoner2013"/>
|-
|'''[[Biology:Omnivore|omnivores]]''' (sometimes called '''''general feeders'''''): birds that forage for a variety of both plant and meat food sources, such as [[Biology:Pheasant|pheasant]]s, tinamouses and [[Biology:Quail|quail]]s. More birds fall under the omnivore classification than any other.<ref name="IrwinStoner2013"/>
|-
|'''piscivores''': birds that forage for and eat fish and other sea life, such as [[Biology:Darter|darter]]s, [[Biology:Loon|loon]]s, [[Biology:Pelican|pelican]]s, [[Biology:Penguin|penguin]]s and [[Biology:Stork|stork]]s.<ref name="Carnaby334"/><ref name="IrwinStoner2013"/>
|-
|'''sanguinivores''': birds that forage for and drink blood, such as [[Biology:Oxpecker|oxpecker]]s and [[Biology:Sharp-beaked ground finch|sharp-beaked ground finch]]es.<ref name="Carnaby334"/><ref name="Klasing1998"/>
|-
|}

{{Term|dimorphism}}
{{defn|''See {{gli|sexual dimorphism}}.''}}

{{Term|diving|content=diving {{anchor|diver|surface diving|plunge diving|surface diver|plunge diver|surface divers|plunge divers|surface-diver|plunge-diver|surface-divers|plunge-divers}} }}
{{defn|''Also defined: '''surface diving'''; '''plunge diving'''.'' Some birds dive into the water for food. Two diving strategies are differentiated: ''surface diving'' birds dive from the surface of the water and swim actively underwater; and ''plunge diving'' birds dive from the air into the water. Plunge diving birds may use the momentum from the plunge to propel themselves underwater, whereas others may swim actively.<ref name="Elphick110-1">{{Harvnb|Elphick|2016|pp=110–111}}</ref>}}

[[File:Eider.a.duvet4.jpg|thumb|alt=refer to caption|A female [[Biology:Common eider|common eider]] sits on her nest, surrounded by {{gli|down feathers}}]]
{{Term|down|content=down {{anchor|down feather|down feathers|downfeather|downfeathers|plumulaceous feather|plumulaceous feathers|plumulaceous}} }}
{{Main|Physics:Down feather}}
{{defn|''Also, '''down feathers''' or '''plumulaceous feathers'''.'' The down of birds—their plumulaceous feathers, as opposed to {{gli|pennaceous feathers}}—are a layer of fine, silky feathers found under the tougher exterior feathers, that are often used by humans as a thermal insulator and padding in goods such as jackets, bedding, pillows and sleeping bags. Considered to be the "simplest" of all feather types,<ref>{{cite book |title=The Integumen: A Textbook of Skin Biology |first=Richard Ian Campbell |last=Spearman |page=[https://archive.org/details/integumenttextbo00spea/page/97 97] |year=1973 |isbn=978-0-521-20048-6 |publisher=Cambridge University Press |url=https://archive.org/details/integumenttextbo00spea/page/97 }}</ref> down feathers have a short or vestigial [[Biology:Rachis|rachis]] (shaft), few barbs and barbules that lack hooks,<ref name="HBW39">{{Harvnb|del Hoyo|Elliott|Sargatal|1992|p=39}}</ref> and (unlike {{gli|contour feathers}}) grow from both the {{gli|pterylae}} and the {{gli|apteria}}.<ref name="Chandler250"/> Very young birds are often only clad in down. The loose structure of down feathers traps air, which helps to insulate birds against heat loss<ref name="Sibley17"/> and contributes to the buoyancy of waterbirds. Species that experience annual temperature fluctuations typically have more down feathers following their autumn moult.<ref name="Scott31">{{Harvnb|Scott|2010|p=31}}</ref> There are three types of down: {{gli|natal down}}, {{gli|body down}} and {{gli|powder down}}.<ref>{{Harvnb|Elphick|2016|pp=75–77}}</ref>}}

{{Term|drumming}}
{{defn|A form of non-vocal communication engaged in by members of the [[Biology:Woodpecker|woodpecker]] family. It involves the {{gli|beak}} striking a hard surface multiple times per second. The drumming pattern, the number of beats per roll and the gap between rolls is specific to each species. Drumming is usually associated with [[Biology:Territory (animal)|territorial behaviour]], with male birds drumming more frequently than females.<ref name=Gorman2014>{{cite book |title=Woodpeckers of the World: A Photographic Guide |last=Gorman|first=Gerard |year=2014|publisher=Firefly Books|isbn=978-1-77085-309-6|page=28}}</ref> ''Drumming'' may also refer to the [[Biology:Drumming (snipe)|sounds]] produced by the specialised outer tail-feathers of [[Biology:Snipe|snipe]] in the course of their courtship display flights.<ref name=BBY>{{cite web |url=http://www.birdsinbackyards.net/species/Gallinago-hardwickii |title=Latham's Snipe - Did you know? |work=Birds in Backyards |publisher=Birdlife Australia |access-date=January 25, 2017 |archive-date=January 25, 2017 |archive-url=https://web.archive.org/web/20170125175936/http://www.birdsinbackyards.net/species/Gallinago-hardwickii |url-status=dead }}</ref>}}

{{Glossary end}}

==E==
[[File:Comparison of eggs by Zureks.jpg|{{gli|Eggs}} of: ostrich, emu, kiwi and chicken|thumb]]
{{Glossary}}
{{Term|ear-coverts|content=ear-coverts {{anchor|ear-covert|ear covert|ear coverts|ear covert feathers|ear covert feather}} }}
{{defn|Small {{gli|covert}} feathers located behind a bird's eye, in one to four rows, which cover the ear opening (bird ears have no external features<ref name="Jasper"/>) and may aid in the acuity of bird hearing.<ref name="FarnerKing2013">{{cite book|last1=Farner|first1=Donald S.|last2=King|first2=James R.|title=Avian Biology|url=https://books.google.com/books?id=CC3LBAAAQBAJ&pg=PA13|year=2013|publisher=Elsevier|isbn=978-1-4832-6942-9|page=13}}</ref>}}

{{Term|egg|content=egg {{anchor|eggs|eggshell|eggshells|egg shell|egg shells|albumen|egg white|egg whites|glair|glaire|yolk|yolks|chalaza|chalazae|egg cell|egg cells}} }}
{{Main|Biology:Egg}}
{{defn|''Also defined: '''eggshell'''; '''yolk'''; '''albumen'''; '''chalaza'''.'' The organic vessel containing the [[Biology:Zygote|zygote]], in which birds develop until hatching. Eggs are usually oval in shape, and have a base white colour from the predominant [[Chemistry:Calcium carbonate|calcium carbonate]] makeup of the outer shell, called the ''eggshell'', though {{gli|passerine}} birds especially may have eggs of other colours,<ref>{{cite book|last=Pycraft|first=W.P.|title=Scientific American: Supplement: The Curious Phenomena of Eggshell Pigmentation|url=https://books.google.com/books?id=lek5AQAAMAAJ&pg=PA376|year=1908|publisher=Munn and Company|page=376}}</ref> such as through deposition of [[Chemistry:Biliverdin|biliverdin]] and its zinc chelate, which give a green or blue ground colour, and protoporphyrin which produces reds and browns.<ref name="HillMcGraw2006">{{cite book|last1=Hill|first1=Geoffrey Edward|last2=McGraw|first2=Kevin J. |title=Bird Coloration: Mechanisms and measurements|url=https://books.google.com/books?id=WnJ8cSoXRMIC&pg=PA368|year=2006|publisher=Harvard University Press|isbn=978-0-674-01893-8|page=368}}</ref> A viable bird egg (as opposed to a non-viable egg: ''see {{gli|addled eggs}}'') consists of a number of structures. The eggshell is 95–97% calcium carbonate crystals, at least in chickens, stabilized by a protein matrix,<ref>{{cite magazine|last1=Arias|first1=J. L.|last2=Fernandez|first2=M. S.|title=Role of extracellular matrix molecules in shell formation and structure|magazine=World's Poultry Science Journal |volume=57|issue= 4|pages=349–357|year=2001|doi=10.1079/WPS20010024|s2cid=86152776}}</ref><ref name="Hunton">{{cite magazine|year=2005|volume=7|issue= 2|pages=67–71|last1=Hunton |first1=P.|title=Research on eggshell structure and quality: an historical overview|magazine=Revista Brasileira de Ciência Avícola|doi=10.1590/S1516-635X2005000200001|doi-access=free}}</ref><ref>{{cite magazine|last1=Nys|first1=Yves|last2=Gautron|first2=Joël|last3=Garcia-Ruiz|first3=Juan M.|last4=Hincke|first4=Maxwell T.|title=Avian eggshell mineralization: biochemical and functional characterization of matrix proteins|magazine=Comptes Rendus Palevol|volume=3|issue= 6–7|pages=549–562|year=2004|doi= 10.1016/j.crpv.2004.08.002}}</ref> without which the crystalline structure would be too brittle to keep its form; the organic matrix is thought to have a role in deposition of calcium during the mineralization process.<ref>{{cite book|last1=Romanoff|first1=Alexis L.|last2=Romanoff|first2=Anastasia J.|year=1949|title=The Avian Egg|location=New York|publisher=Wiley|oclc=191965542}}</ref><ref>{{cite book|last1=Burley|first1=R.W.|last2=Vadehra|first2=Dharam V.|year=1989|title=The Avian Egg: Chemistry and Biology|location=New York|publisher=Wiley|isbn=978-0-471-84995-7}}</ref><ref>{{cite magazine|last1=Lavelin|first1=I., N.|last2=Meiri|first2=M. Pines|year=2000|title=New insight in eggshell formation|magazine=Poultry Science|volume=79|issue= 7|pages=1014–1017|doi=10.1093/ps/79.7.1014|pmid=10901204|doi-access=free}}</ref> The structure and composition of the avian eggshell serves to protect the egg against damage and microbial contamination, prevention of desiccation, regulation of gas and water exchange for the growing embryo and provides calcium for [[Biology:Embryogenesis|embryogenesis]].<ref name="Hunton"/> Inside the eggshell are two shell membranes (inner and outer), and at the center is a yolk—a spherical structure, usually some shade of yellow, to which the fertilized [[Biology:Gamete|gamete]] attaches and which the embryonic bird uses as sustenance as it grows. The yolk is suspended in the albumen (also called ''egg white'' or ''glair''&thinsp;/&thinsp;''glaire'') by one or two spiral bands of tissue called the [[Biology:Chalaza|chalaza]]e.<ref name="Alderton1998">{{cite book|last=Alderton|first=David|title=The Complete Guide to Bird Care|url=https://archive.org/details/completeguidetob00davi|url-access=registration|year=1998|publisher=Howell Book House|isbn=978-0-87605-038-5}}</ref> The albumen protects the yolk and provides additional nutrition for the embryo's growth,<ref name="Harrison2011">{{cite book|last=Harrison|first=John |title=Backgarden Chickens and Other Poultry|url=https://books.google.com/books?id=q4DABAAAQBAJ&pg=PT125|year=2011|publisher=Little, Brown Book Group|isbn=978-0-7160-2276-3|page=125}}</ref> though it is made up of approximately 90% water in most birds.<ref name="Damerow2013">{{cite book|last=Damerow|first=Gail |title=Hatching & Brooding Your Own Chicks: Chickens, Turkeys, Ducks, Geese, Guinea Fowl|url=https://books.google.com/books?id=gvq9maYXTw8C&pg=PA142|year=2013|publisher=Storey Publishing|isbn=978-1-60342-878-1|page=142}}</ref> Prior to fertilization, the yolk is a single [[Biology:Cell|cell]] ovum or egg cell; one of the few single cells that can be seen by the naked eye.<ref name="Patten2008">{{cite book|last=Patten|first=Bradley M.|title=Early Embryology of the Chick|url=https://books.google.com/books?id=W3i643aSE_MC&pg=PA17|year=2008|publisher=Wildside Press LLC|isbn=978-1-4344-7385-1|page=17}}</ref>}}

{{Term|egg binding|content=egg binding {{anchor|egg bindings}} }}
{{defn|An egg that while traversing the reproductive tract during the process of being laid, becomes stuck near to the opening of the {{gli|cloaca}} or further inside the oviduct.<ref>{{Cite episode|series=Dr. K's Exotic Animal ER|title=Sumo Dragon|series-link=Dr. K's Exotic Animal ER|network=Nat Geo Wild|date=May 21, 2016|minutes=26|season=03 E01}}</ref> The condition may be caused by obesity, nutritional imbalances such as calcium deficiency, environmental stress such as temperature changes, or malformed eggs.<ref>{{cite magazine|last1=Stout|first1=Jane D.|title=Common emergencies in pet birds|magazine=The Veterinary Clinics of North America. Exotic Animal Practice|date=May 2016|volume=19|issue= 2|pages=513–41|doi=10.1016/j.cvex.2016.01.002|pmid=26948267}}</ref> }}

{{Term|egg incubation|content=egg incubation {{anchor|egg incubating|incubation|incubating}} }}
{{Main|Biology:Egg incubation}}
{{defn|''Also, '''brooding'''.'' The general care of unhatched eggs by parent birds (more often by females but by birds of both sexes), especially by temperature regulation through sitting on them, crouching or squatting over them, covering them with their wings, providing shade, wetting eggs and related behaviours. The target temperature of most species is {{convert|37|C}} to {{convert|38|C}}. In monogamous species incubation duties are often shared, whereas in polygamous species one parent is wholly responsible for incubation. Warmth from parents passes to the eggs through {{gli|brood patches}}—areas of bare skin on the abdomen or breast of the incubating birds. Incubation can be an energetically demanding process; adult [[Biology:Albatross|albatross]]es, for instance, lose as much as {{convert|83|g}} of body weight per day of incubation.<ref name="Barrows2000">{{cite book|last=Barrows|first=Edward M.|title=Animal Behavior Desk Reference: A Dictionary of Animal Behavior, Ecology, and Evolution, Second Edition|url=https://archive.org/details/animalbehaviorde0000barr|url-access=registration|year=2000|publisher=CRC Press|isbn=978-0-8493-2005-7|page=[https://archive.org/details/animalbehaviorde0000barr/page/79 79]}}</ref><ref name="Gill1459">{{Harvnb|Gill|1995|p=459}}</ref><ref>{{cite book|last1=Warham|first1=J|year=1990|title=The Petrels: Their Ecology and Breeding Systems|location=London|publisher=Academic Press|isbn=978-0-12-735420-0}}</ref>}}

[[File:Poicephalus senegalus -egg tooth -two weeks-21July07.JPG|thumb|A [[Biology:Senegal parrot|Senegal parrot]] chick at about two weeks after hatching. The {{gli|egg tooth}} is near the tip of its beak on the {{gli|upper mandible}}.]]
{{Term|egg tooth|content=egg tooth {{anchor|egg teeth|eggtooth|eggteeth}} }}
{{defn|A small, sharp, calcified projection on the beak that full-term chicks of most bird species have, which they use to chip their way out of their egg.<ref name="Campbell178">{{Harvnb|Campbell|Lack|1985|p=178}}</ref> This white spike is located near the tip of the {{gli|upper mandible}} in most species (e.g., [[Biology:Gull|gull]]s);<ref name="Jehl">{{cite magazine |magazine=The Wilson Bulletin | first=Joseph R. Jr. | last=Jehl |volume=80 |issue=3 |pages=328–9|title=The Egg Tooth of Some Charadriiform Birds |url=https://sora.unm.edu/sites/default/files/journals/wilson/v080n03/p0328-p0330.pdf |date=September 1968}}</ref> near the tip of the {{gli|lower mandible}} instead in a minority of others, such as [[Biology:Northern lapwing|northern lapwing]]s;<ref name="Jehl" /> with a few species, such as Eurasian whimbrels, [[Biology:Black-winged stilt|black-winged stilt]]s and [[Biology:Semipalmated sandpiper|semipalmated sandpiper]]s,<ref name="Jehl" /> having one on each mandible.<ref name="Perrins">{{cite book |title=New Generation Guide to the Birds of Britain and Europe |first1=Christopher M. |last1=Perrins |first2=David |last2=Attenborough |first3=Norman |last3=Arlott |publisher=University of Texas Press |location=Austin, TX |year=1987 |isbn=978-0-292-75532-1 |page=205}}</ref> Despite its name, the projection is not an actual [[Biology:Tooth|tooth]] (as the similarly-named projections of some [[Biology:Reptile|reptile]]s are); instead, it is part of the integumentary system, as are [[Biology:Claw|claw]]s and {{gli|scales}}.<ref>{{cite magazine |magazine=The Wilson Bulletin | first=George A. Jr. | last=Clark |volume=73 |issue= 3 |pages=268–278 |title=Occurrence and Timing of Egg Teeth in Birds |url=http://sora.unm.edu/sites/default/files/journals/wilson/v073n03/p0268-p0278.pdf |date=September 1961}}</ref> The hatching chick first uses its egg tooth to break the membrane around an air chamber at the wide end of the egg. Then it pecks at the eggshell while turning slowly within the egg, eventually (over a period of hours or days) creating a series of small circular fractures in the shell.<ref name="Gill427">{{Harvnb|Gill|1995|p=427}}</ref> Once it has breached the egg's surface, the chick continues to chip at it until it has made a large hole. The weakened egg eventually shatters under the pressure of the bird's movements.<ref name="Gill428">{{Harvnb|Gill|1995|p=428}}</ref> The egg tooth is so critical to a successful escape from the egg that chicks of most species will perish unhatched if they fail to develop one.<ref name="Perrins"/>}}

{{Term|emargination|content=emargination {{anchor|emarginations}} }}
{{defn|A pronounced narrowing at some variable distance along the feather edges at the outermost {{gli|primaries}} of large soaring birds, particularly raptors. Whether these narrowings are called {{gli|notches}} or emarginations' depends on the degree of their slope.<ref name="Campbell656"/> An emargination is a gradual change, and can be found on either side of the feather. A notch is an abrupt change, and is only found on the wider trailing edge of the remige. The presence of notches and emarginations creates gaps at the wingtip; air is forced through these gaps, increasing the generation of lift.<ref name="Trail6">{{Harvnb|Trail|2001|p=6}}</ref>}}

{{Term|eye-ring|content=eye-ring {{anchor|eye-rings|eye ring|eye rings|eyering|eyerings|orbital ring|orbital ring|orbital rings|orbital-ring|orbital-rings|eye arc|eye-arc|eye arcs|eye-arcs}} }}
{{Main|Biology:Eye-ring}}
{{defn|''Also defined: '''orbital ring'''.'' A visible ring of feathers around a bird's eye; the eye-ring is often paler than the surrounding feathers. By contrast, an orbital ring is bare skin ringing the eye. In some species, such as [[Biology:Little ringed plover|little ringed plover]], the orbital ring may be quite conspicuous.<ref name="Vinicombe14"/>}}

{{Term|eyestripe|content=eyestripe {{anchor|eye stripe|eye-stripe|eyeline|eye line|eye-line}} }}
{{defn|''Also, '''eye line'''&thinsp;/&thinsp;'''eyeline'''.'' A visible stripe on the feathers of a bird's head, often darker than the surrounding feathers, running through the eye region.<ref name="Vinicombe14"/> ''Compare {{gli|supercilium}}''.}}
{{Gallery
|title=Eye features
|width=150
|height=180
|align=center
|File:Blue-headed Vireo-cropped.jpeg|Blue-headed vireo, with a conspicuous {{gli|eye-ring}}
|File:Little ringed plover-chick-cropped.jpeg|[[Biology:Little ringed plover|Little ringed plover]] chick, with a conspicuous {{gli|orbital ring}}
|File:White-eared Sibia-Taiwan-cropped-eyestripe.jpeg|[[Biology:White-eared sibia|White-eared sibia]], with a conspicuous {{gli|eyestripe}}
|File:Saxicola rubetra -Belgium -male-8-cropped.jpeg|[[Biology:Whinchat|Whinchat]], with a conspicuous {{gli|supercilium}} (eyebrow)
}}
{{Glossary end}}


==F==
[[File:Types de plumes. - Larousse pour tous, -1907-1910-.jpg|thumb|250px|{{gli|Feather}} variations]]
{{Glossary}}
{{Term|term=feather|content=feather {{anchor|feathers}} }}
{{defn|[[Biology:Epidermis (zoology)|Epidermal]] growths that form the distinctive outer covering, or [[Biology:Plumage|plumage]], on birds. They are considered the most complex integumentary structures found in vertebrates,<ref name="Prum2002">{{cite magazine|last1=Prum|first1=Richard O.|last2=Brush|first2=A.H.|year=2002|title=The evolutionary origin and diversification of feathers|magazine=[[Biology:The Quarterly Review of Biology|The Quarterly Review of Biology]]|volume=77|issue= 3 |url=http://www.yale.edu/eeb/prum/pdf/Prum_n_Brush_2002.pdf |pages=261–295|doi=10.1086/341993|pmid=12365352}}</ref><ref name="Prum2003">{{cite magazine|doi=10.1038/scientificamerican0303-84 |date = March 2003|last1=Prum|first1=Richard O.|last2=Brush|first2=A.H.|title=Which Came First, the Feather or the Bird?|magazine=Scientific American |volume=288 |issue= 3 |pages=84–93 |url=http://www.yale.edu/eeb/prum/pdf/Prum_n_Brush_2003.pdf|pmid=12616863|bibcode = 2003SciAm.288c..84P}}</ref> and, indeed, a premier example of a complex [[Biology:Evolutionary developmental biology#The origins of novelty|evolutionary novelty]].<ref name="Prum1999">{{cite magazine|doi=10.1002/(SICI)1097-010X(19991215)285:4<291::AID-JEZ1>3.0.CO;2-9|year=1999|last1=Prum|first1=Richard O.|title=Development and Evolutionary Origin of Feathers |magazine=Journal of Experimental Zoology  |volume=285|issue= 4 |pages=291–306 |pmid=10578107 |url=http://prumlab.yale.edu/sites/default/files/prum_1999_mde_development.pdf}}</ref> Feathers are among the characteristics that distinguish the extant birds from other living groups.<ref name="iridescence">{{cite magazine |last=Li |first=Quanguo |title=Reconstruction of ''Microraptor'' and the Evolution of Iridescent Plumage |magazine=Science |volume=335 |issue= 6073 |pages=1215–1219 |date=March 9, 2012 |doi=10.1126/science.1213780 |pmid=22403389 |bibcode=2012Sci...335.1215L|s2cid=206537426}}</ref> Although feathers cover most parts of the body of birds, they arise only from certain well-defined {{gli|pterylosis|tracts}} on the skin. They aid in flight, thermal insulation and waterproofing, with their colouration helping in communication and [[Biology:Crypsis|protection]].<ref name="Pettingill29">{{Harvnb|Pettingill|1985|p=29}}</ref> Although there are many subdivisions of feathers, at the broadest levels, feathers are either classified as i) {{gli|vaned feathers}}, which cover the exterior of the body and include {{gli|pennaceous feathers}}, or ii) {{gli|down feathers}}, which grow underneath the vaned feathers. A third rarer type of feather, the {{gli|filoplume}}, is hairlike and (if present in a bird; they are entirely absent in ratites<ref name="Chandler285">{{Harvnb|Chandler|1916|p=285}}</ref>) grows alongside the contour feathers.<ref name="Prum2002"/> A typical vaned feather features a main shaft called the {{gli|quill}} with an upper section called the {{gli|rachis}}. Fused to the rachis are a series of branches, or {{gli|barbs}}; the barbs in turn have {{gli|barbules}} branching off them, and they in turn branch yet again with a series of growths called {{gli|barbicels}}, some of which have minute hooks called {{gli|hooklets}} for cross-attachment. Down feathers are fluffy because they lack barbicels, so the barbules float free of each other, allowing the down to trap air and provide excellent thermal insulation. At the base of the feather, the rachis expands to form the hollow tubular {{gli|calamus}} which inserts into a follicle in the [[Biology:Skin|skin]]. The basal part of the calamus is without vanes. This part is embedded within the skin follicle and has an opening at the base ({{gli|proximal umbilicus}}) and a small opening on the side ({{gli|distal umbilicus}}).<ref name="atlas">{{Cite book|title=A color atlas of avian anatomy|last= McLelland| first=J.|publisher=W.B. Saunders Co.|year=1991|isbn=978-0-7216-3536-1}}</ref>}}

{{Term|feather pecking|content=feather pecking {{anchor|feather-pecking}} }}
{{main|Biology:Feather pecking}}
{{defn|A behavioural problem in which one bird repeatedly pecks at the feathers of another, that occurs most frequently amongst [[Biology:Chicken|domestic hens]] reared for egg production,<ref>{{cite magazine|last1=Huber-Eicher|first1=B.|last2=Sebo|first2=F.|magazine=Applied Animal Behaviour Science|title=The prevalence of feather pecking and development in commercial flocks of laying hens|issue= 3|volume=74|pages=223–231|year=2001|doi=10.1016/S0168-1591(01)00173-3}}</ref><ref>{{cite magazine|last1=Sherwin|first1=C.M.|last2=Richards|first2=G.J|last3=Nicol|first3=C.J.|magazine=British Poultry Science|title=A comparison of the welfare of layer hens in four housing systems in the UK|volume=51|issue= 4|year=2010|pages=488–499|doi=10.1080/00071668.2010.502518|pmid=20924842|s2cid=8968010}}</ref> although it is seen in other poultry such as [[Biology:Pheasant|pheasant]]s,<ref>{{cite magazine|last1=Butler|first1=D.A.|last2=Davis|first2=C.|magazine=Veterinary Record|title=Effects of plastic bits on the condition and behaviour of captive-reared pheasants|volume=166 |pages=398–401|issue= 13|year=2010|doi=10.1136/vr.b4804|pmid=20348469|s2cid=7549266}}</ref> [[Biology:Domestic turkey|turkeys]],<ref>{{cite book|last1=Sherwin|first1=C.M.|editor-last1=Pond|editor-first1=Wilson G.|editor-last2=Bell|editor-first2=Alan W.|publisher=Marcel Dekker|title=The Encyclopaedia of Animal Science|chapter=Turkeys: Behavior, Management and Well-Being|year=2010|pages=847–849}}</ref> ducks<ref>{{cite magazine|last1=Gustafson|first1=Leslie A.|last2=Cheng|first2=Heng-Wei |last3=Garner|first3= Joseph P.|last4=Pajorc|first4=Edmond A.|last5=Mench|first5=Joy A. |magazine=Applied Animal Behaviour Science|title= Effects of bill-trimming Muscovy ducks on behavior, body weight gain, and bill morphopathology|volume=103|issue=1–2 |year=2007|pages=59–74|doi=10.1016/j.applanim.2006.04.003}}</ref> and sometimes in farmed [[Biology:Ostrich|ostrich]]es.<ref>{{cite magazine|last1=Reischl|first1=E.|last2=Sambraus|first2=H.H.|year=2003|title=Feather-pecking of African ostriches in Israel|magazine=Tierarztliche Umschau|volume=58|issue= 7|pages=364–369|doi=}}</ref> Two levels of severity are recognised: "gentle" and "severe".<ref>{{cite magazine|last1=McAdie|first1= T.M.|last2=Keeling|first2=L.J.|magazine=Applied Animal Behaviour Science|title=The social transmission of feather pecking in laying hens: effects of environment and age|issue= 2|volume=75|pages=147–159|year=2002|doi=10.1016/S0168-1591(01)00182-4}}</ref>}}

[[File:Ara militaris.jpg|thumb|The [[Biology:Military macaw|military macaw]] on the left is displaying signs of {{gli|feather-plucking}}.]]

{{Term|feather-plucking|content=feather-plucking {{anchor|feather plucking|feather-picking|feather picking|pterotillomania|feather damaging behaviour}} }}
{{defn|''Also '''feather-picking''', '''feather damaging behaviour''' or '''pterotillomania'''.''<ref name="Lumeij and Hommers, 2008">{{cite magazine|last1=Lumeij|first1=Johannes T.|last2=Hommers|first2=Caroline J.|year=2008|title=Foraging 'enrichment' as treatment for Pterotillomania|magazine=Applied Animal Behaviour Science|volume=111|issue=1–2|pages=85–94|url=http://img2.tapuz.co.il/forums/1_148363975.pdf|doi=10.1016/j.applanim.2007.05.015|access-date=2020-12-20|archive-date=2015-11-23|archive-url=https://web.archive.org/web/20151123180457/http://img2.tapuz.co.il/forums/1_148363975.pdf|url-status=dead}}</ref> A [[Philosophy:Adaptive behavior|maladaptive]], behavioural disorder commonly seen in captive birds which chew, bite or pluck their own feathers with their beak, resulting in damage to the feathers and occasionally the skin.<ref>{{cite web|url=http://www.beautyofbirds.com/featherplucking.html|title=Feather Plucking in Pet Birds|website=Beauty of Birds|year=2011|access-date=December 21, 2020}}</ref><ref>{{cite web|url=https://www.purdue.edu/uns/html4ever/2005/051221.Garner.parrots.html|title=Parrots' behaviors mirror human mental disorders|date=December 21, 2005|access-date=December 21, 2020|last=Steeves|first=Susan A.|publisher=Purdue University}}</ref> It is especially common among Psittaciformes, with an estimated 10% of captive parrots exhibiting the disorder.<ref name="van Zeeland et al. 2009">{{cite magazine|last1=van Zeeland|first1= Yvonne R.A.|last2=Spruit|first2=Berry M.| last3=Rodenburg|first3=T. Bass|title= Feather damaging behaviour in parrots: A review with consideration of comparative aspects| magazine=Applied Animal Behaviour Science|volume=121|issue= 2|pages=75–95| doi=10.1016/j.applanim.2009.09.006|date=November 2009|url=https://www.sciencedirect.com/science/article/abs/pii/S0168159109002561|display-authors = etal}}</ref> The chief areas of the body that are pecked or plucked are the more accessible regions such as the neck, chest, {{gli|flank}}, inner thigh and [[Biology:Anatomical terms of location#Dorsal and ventral|ventral]] wing area. {{gli|Contour}} and {{gli|down feathers}} are generally identified as the main targets, although in some cases, {{gli|tail}} and {{gli|flight feathers}} are affected. Although feather-plucking shares characteristics with {{gli|feather pecking}}, commonly seen in commercial poultry, the two behaviours are currently considered to be distinct, as in the latter, the birds peck at and pull out the feathers of ''other individuals''.}}

{{Term|feather tract}}
{{defn|''See: {{gli|pterylae}}.''}}

{{Term|term=fecal sac|content=fecal sac {{anchor|fecal sac|fecal sacs|faecal sac|faecal sacs}} }}
{{Main|Biology:Fecal sac}}
{{defn|''Also, '''faecal sac'''.'' A mucous membrane, generally white or clear with a dark end,<ref>{{cite book|last1=Choiniere|first1= J.|last2=Mowbray Golding| first2= C.|last3=Vezo|first3=T.|year=2005|title=What's That Bird?|page=[https://archive.org/details/whatsthatbirdget00choi/page/33 33]|publisher=Storey Publishing|isbn=978-1-58017-554-8|url=https://archive.org/details/whatsthatbirdget00choi/page/33}}</ref> that surrounds the [[Biology:Feces|feces]] of some species of {{gli|nestling}} birds,<ref name="Sibley78">{{Harvnb|Sibley, et al.|2001|p=78}}</ref> and allows parent birds to more easily remove [[Biology:Feces|fecal material]] from the nest. The nestling usually produces a fecal sac within seconds of being fed; if not, a waiting adult may prod around the youngster's [[Biology:Cloaca|cloaca]] to stimulate [[Biology:Excretion|excretion]].<ref name="Campbell433">{{Harvnb|Campbell|Lack|1985|p=433}}</ref> Young birds of some species adopt specific postures or engage in specific behaviours to signal that they are producing fecal sacs.<ref name=OConnor>{{cite book|last = O'Connor |first=R. J.|year=1984|title=The Growth and Development of Birds| page=174| publisher=Wiley Interscience| isbn=978-0-471-90345-1}}</ref> For example, nestling [[Biology:Curve-billed thrasher|curve-billed thrasher]]s raise their posteriors in the air, while young [[Biology:Cactus wren|cactus wren]]s shake their bodies.<ref>{{cite magazine|last=Ricklefs|first=R. E.|year= 1996|magazine=The Wilson Bulletin|title=Behavior of Young Cactus Wrens and Curve-billed Thrashers|volume=78|issue= 1|pages=47–56|url= http://elibrary.unm.edu/sora/Wilson/v078n01/p0047-p0056.pdf|archive-url=https://web.archive.org/web/20081010223857/http://elibrary.unm.edu/sora/Wilson/v078n01/p0047-p0056.pdf|archive-date=October 10, 2008|url-status=dead}}</ref> Other species deposit the sacs on the rim of the nest, where they are likely to be seen (and removed) by parent birds.<ref name=OConnor/> Not all species generate fecal sacs. They are most prevalent in {{gli|passerines}} and their near relatives, which have young that remain in the nest for longer periods.<ref name="Campbell433"/>}}

[[File:Goose filoplume illustration-1895.jpg|thumb|upright=0.65|Illustration of a goose {{gli|filoplume}} feather, from ''The Structure and Life of Birds'' (1895).]]
{{Term|term=filoplume|content=filoplume {{anchor|filoplumes|filoplume feather|filoplume feathers}} }}
{{defn|''Also, '''filoplume feather'''; '''hair feather''', '''thread feather'''.'' A hairlike type of feather that, if present in a bird (they are entirely absent in ratites<ref name="Chandler285"/>) grows alongside the contour feathers.<ref name="Prum2002"/> The typical filoplume is silky in appearance, lacks pith and a {{gli|superior umbilicous}} opening, has a very slender, straight shaft lacking differentiation into {{gli|calamus}} and {{gli|rachis}}, and is naked or has only a few {{gli|barbs}} (that lack cross-attachment) at the distal end. They are closely associated with {{gli|contour feathers}} and often entirely hidden by them, with one or two filoplumes attached and sprouting from near the same point of the skin as each contour feather, at least on a bird's head, neck and trunk.<ref name="Nitzsch1867">{{cite book|last=Nitzsch|first=Christian Ludwig|title=Nitzsch's Pterylography|url=https://books.google.com/books?id=O_NFAAAAcAAJ&pg=PA14|year=1867|publisher=Ray Society|page=14}}</ref><ref name="Chandler261">{{Harvnb|Chandler|1916|p=261}}</ref> Filoplume feathers host a cluster of sensory corpuscles at their base,<ref name="Proctor96">{{Harvnb|Proctor|Lynch|1998|p=96}}</ref> that serve to detect air currents that affect contour and flight feathers.<ref name="Stettenheim"/> Filoplumes are one of the three major classes of feathers, the others being {{gli|pennaceous}} and {{gli|plumulaceous}} feathers.}}

{{Term|term=flange|content=flange {{anchor|flanges|recurved margin|recurved margins|feather flange|feather flanges}} }}
{{defn|''Also, '''recurved margin'''.'' "The thickened dorsal edge of the bases of pennaceous {{gli|barbules}}, generally recurved in proximal barbules, and frequently so in distal barbules also"<ref name="Chandler253">{{Harvnb|Chandler|1916|p=253}}</ref> which anchor the {{gli|hooklets}}.<ref name="Pettingill32-33"/> (''See [[:File:The Interlocking of feathers.png|diagram]]; refer to figures 3 [in which the flange is referred to as the "folded edge"] and 6 [in which the mechanism of interlocking between a flange and {{gli|hooklet}} is shown''].)}}

{{Term|term=flanks|content=flanks {{anchor|flank}} }}
{{defn|The {{gli|topography|topographical}} region of the {{gli|underparts}}{{efn|In relation to ''flanks'' being defined as under parts, in the treatise ''Ornithology in Laboratory and Field'', the author states: "[a]lthough technically the sides of the body belong to both the {{gli|upper parts}} and the {{gli|lower parts}}, the imaginary line separating the two surfaces is so high on the trunk that the sides of the body are generally considered under parts only."<ref name="Pettingill9"/>}} sketched "between the posterior half of the abdomen and the {{gli|rump}}".<ref name="Pettingill9"/>}}

{{Term|term=fledge|content=fledge {{anchor|fledging|fledges|fledged}} }}
{{defn|''Also, '''fledging'''.'' The stage in a young bird's life when the feathers and wing muscles are sufficiently developed for flight, or describing the act of a chick's parents in raising it to that time threshold.<ref name="Eastman2000">{{cite book|last=Eastman|first=John|title=Birds of Field and Shore: Grassland and Shoreline Birds of Eastern North America|url=https://books.google.com/books?id=lfSldAchKFYC&pg=PR13|year=2000|publisher=Stackpole Books|isbn=978-0-8117-2699-3|page=13}}</ref>}}

{{Term|term=fledgling|content=fledgling {{anchor|fledglings}} }}
{{defn|A juvenile bird during the period it is venturing from or has left the {{gli|nest}} and is learning to run and fly; a young bird during the period immediately after {{gli|fledging}}, when it is still dependent upon parental care and feeding.<ref name="Stiteler2013">{{cite book|last=Stiteler|first=Sharon |title=1001 Secrets Every Birder Should Know: Tips and Trivia for the Backyard and Beyond|url=https://books.google.com/books?id=v6UAQB0Ra6QC&pg=PT389|year=2013|publisher=Running Press|location=London|isbn=978-0-7624-4832-6|page=389}}</ref>}}

{{Term|term=flight|content=flight {{anchor|fly|flying|bird flight|bird flying}} }}
{{defn|Most birds can [[Biology:Flying and gliding animals|fly]], which distinguishes them from almost all other vertebrate classes (''cf. bats and [[Biology:Pterosaur|pterosaur]]s''). Flight is the primary means of locomotion for most bird species and is used for breeding, feeding and predator avoidance and escape. Birds have various adaptations for flight, including a lightweight skeleton, two large flight muscles, the pectoralis (which accounts for 15% of the total mass of the bird) and the supracoracoideus, as well as modified forelimbs ([[Physics:Wing|wing]]s) that serve as [[Physics:Airfoil|aerofoil]]s.<ref name="Gillvarious">{{Harvnb|Gill|1995|p=136, et seq.}}</ref> Wing shape and size generally determine a bird species' type of flight; many birds combine powered, flapping flight with less energy-intensive soaring flight. About 60 extant bird species are flightless, as were many extinct birds.<ref name="Rootsvarious">{{harvnb|Roots|2006|p=various}}</ref> Flightlessness often arises in birds on isolated islands, probably due to limited resources and the absence of land predators.<ref>{{cite magazine|last=McNab |first=Brian K. |date=October 1994 |title=Energy Conservation and the Evolution of Flightlessness in Birds |magazine=The American Naturalist |volume=144 |issue= 4 |pages=628–42 |doi=10.1086/285697 |jstor=2462941}}</ref> Though flightless, penguins use similar musculature and movements to "fly" through the water, as do [[Biology:Auk|auk]]s, [[Biology:Shearwater|shearwater]]s and [[Biology:Dipper|dipper]]s.<ref>{{cite magazine|last1=Kovacs |first1=Christopher E. |year=2000 |title=Anatomy and histochemistry of flight muscles in a wing-propelled diving bird, the Atlantic Puffin, ''Fratercula arctica'' |magazine=Journal of Morphology |volume=244 |issue= 2 |pages=109–25|doi=10.1002/(SICI)1097-4687(200005)244:2<109::AID-JMOR2>3.0.CO;2-0 |pmid=10761049 |last2=Meyers |first2=RA}}</ref>}}

[[File:Parts of feather modified.jpg|thumb|upright=0.8|'''Parts of a feather:''' {{ordered list|{{gli|vane}}|{{gli|rachis}}|{{gli|barb}}|{{gli|afterfeather}}|{{gli|calamus}} }}]]
{{Term|term=flight feather|content=flight feather {{anchor|flight feathers|Pennae volatus}} }}
{{main|Biology:Flight feather}}
{{defn|''Also, '''Pennae volatus'''.''<ref name="HAA">{{cite book|title=Handbook of Avian Anatomy: Nomina Anatomica Avium|last=Baumel|first=Julian J.|year=1993|publisher=Nuttall Ornithological Club}}</ref> The long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the tail or [[Physics:Wing|wing]]s of a bird; those on the tail are called {{gli|rectrices}} (''singular: {{gli|rectrix}}''), while those on the wings are called {{gli|remiges}} (''singular: {{gli|remex}}''). Based on their location, remiges are subdivided into {{gli|primaries}}, {{gli|secondaries}} and {{gli|tertiaries}}.<ref>{{cite book|title=The Century Dictionary and Cyclopedia|last=Whitney|first=William Dwight|publisher=The Century Co| year=1906|series=Entry for "Feather"| url=https://archive.org/details/bub_gb_U_FOAAAAYAAJ| page=[https://archive.org/details/bub_gb_U_FOAAAAYAAJ/page/n624 2], 164|oclc=825679}}</ref>}}

{{Term|term=foot paddling|content=foot paddling {{anchor|foot paddling}} }}
{{defn|A foraging behaviour of gulls in which individuals stand at a location, often in shallow water, and perform rapid stepping actions that are thought to make subterranean worms or other food rise to the surface.<ref>{{cite magazine |first=P. A.|last=Buckley|date=January–December 1966|title=Foot-paddling in Four American Gulls, with Comments on its Possible Function and Stimulation|magazine=Ethology|volume=23|issue= 4|pages=395–402|pmid=5992179}}</ref>}}

{{Term|forehead}}
{{defn|The portion of a bird's head extending "up and back from the {{gli|bill}} to an imaginary line joining the anterior corners of the eyes".<ref name="Pettingill10"/>}}

{{Term|fovea|content=fovea {{anchor|foveas|foveae|fovea centralis|temporal fovea}} }}
{{Main|Medicine:Fovea centralis}}
{{defn|''Plural: '''foveas''' or '''foveae'''.'' A small cavity in the [[Biology:Retina|retina]] of the eye that hosts a large number of light receptors; more than anywhere else on the retina. About one half of bird species with fovea have a single one, but uniquely in birds,<ref>{{cite book|last=Walls|first=Gordon L.|title=Bulletin: The Vertebrate Eye and its Adaptive Radiation|chapter-url=https://archive.org/details/vertebrateeyeits00wall/page/188|year=1942|publisher=The Cranbrook Institute of Science|page=188|chapter=Adaptations to Diurnal Activity}}</ref> some, such as [[Biology:Tern|tern]]s, [[Biology:Kingfisher|kingfisher]]s and [[Biology:Hummingbird|hummingbird]]s, have a second fovea,<ref name="Holden2016">{{cite book|last=Holden|first=Peter |title=RSPB Birds: their Hidden World|url=https://books.google.com/books?id=3XcDCwAAQBAJ&pg=PA245|year=2016|publisher=Bloomsbury Publishing|location=London|isbn=978-1-4729-3224-2|page=245}}</ref> called the temporal fovea, that assists in judging speed and distance and increases visual acuity. Birds that do not have a second fovea will sometimes bob their head to improve their visual field.<ref>{{Harvnb|Elphick|2016|p=61}}</ref>}}

{{Term|term=friction barbules|content=friction barbules {{anchor|friction barbule|locking barbule|locking barbules}} }}
{{defn|A specialized type of {{gli|barbule}} located on the distal part of the inner {{gli|vane}} of {{gli|primary feathers}} on the wings of most flighted birds. Friction barbules support lobe-shaped ("lobular") {{gli|barbicels}} that are broader than the typical barbicel hosted by other vaned feathers, and which in turn support more {{gli|hooklets}}. The theory is that the augmented surface area and other adaptations significantly increases grip through [[Physics:Friction|friction]] when the outer web of barbs of one primary feather come into contact and rub against the inner web of barbs of another primary feather it overlays, thereby preventing slippage during the rigors of flight.<ref name="Gill84">{{Harvnb|Gill|1995|p=84}}</ref><ref>{{cite magazine|magazine=Bulletin of the British Ornithologists' Club|last=Davison|first=G. W. H.|volume=103|issue= 3|title=Notes on the Extinct Argusianus Bipuntatus|page=87|date=November 1982|url=https://www.biodiversitylibrary.org/item/123798#page/103/mode/1up}}</ref> Friction barbules are found only on those parts of primary feathers that are in "zones of overlap" with neighboring primaries. The theory (and the use of "friction" in the title of the defined phrase) has been criticized. In ''Avian Flight'' (2005), the author notes that "most birds open and close their wings during every wing beat cycle", and proposes that the energetic cost to overcome friction during the "wing extension and flexion" of each beat cycle would be prohibitive. Offered instead is the theory that the function of these specialized barbules is to lock the primary feathers together on the wings' downstroke, during which high [[Physics:Pressure|pressure]] from below the wings' surface would otherwise tend to cause the feathers to spread.<ref name="Videler2006">{{cite book|last=Videler|first=John J.|title=Avian Flight|url=https://books.google.com/books?id=5Xr9NZdgzP0C&pg=PA58|year=2005|publisher=OUP Oxford|isbn=978-0-19-929992-8|pages=58–61}}</ref>}}

{{Term|term=frontal shield|content=frontal shield {{anchor|frontal shields|facial shield|frontal plate|facial shields|frontal plates|face shield|face shields}} }}
{{main|Biology:Frontal shield}}
{{defn|''Also  '''facial shield'''; '''face shield'''; '''frontal plate'''.'' A hard or fleshy plate extending from the base of the {{gli|upper mandible}} over the {{gli|forehead}} of several bird species including some [[Biology:Water bird|water bird]]s in the [[Biology:Rallidae|rail family]], especially the [[Biology:Moorhen|gallinules and moorhens]], [[Biology:Swamphen|swamphen]]s and [[Biology:Coot|coot]]s, as well as in [[Biology:Jacanidae|jacana]].<ref name="Campbell533">{{Harvnb|Campbell|Lack|1985|p=533}}</ref> While most face shields are made up of fatty tissues, some birds, such as certain [[Biology:Turaco|turaco]]s, e.g., the [[Biology:Red-crested turaco|red-crested turaco]], have face shields that are hard extensions of the mandible.<ref name="Grouw2013">{{cite book|last=Grouw|first=Katrina Van |title=The Unfeathered Bird|url=https://books.google.com/books?id=wYrPAwRh95gC&pg=PA58|year=2013|publisher=Princeton University Press|isbn=978-0-691-15134-2|page=58}}</ref> The size, shape and colour may exhibit [[Chemistry:Testosterone|testosterone]]-dependent variation in either sex during the year.<ref>{{cite magazine |vauthors=Alvareza F, Sanchez CS, Angulo S |year= 2005|title= The frontal shield of the moorhen: sex differences and relationship with body condition|magazine= Ethology, Ecology & Evolution|volume=17|issue= 2|pages=135–148 |doi= 10.1080/08927014.2005.9522603|url= |citeseerx= 10.1.1.158.6095|s2cid= 85892241}}</ref> Functionality appears to relate to protection of the face while feeding in or moving through dense vegetation, as well as to [[Biology:Courtship display|courtship display]] and [[Biology:Territory (animal)|territorial]] defence.<ref>{{cite magazine |last=Gullion|first=Gordon W.|year=1951|title=The frontal shield of the American Coot|magazine=Wilson Bulletin|volume=63|issue= 3|pages=157–166}}</ref> ''Compare: {{gli|casque}}''.}}

{{Term|term=furcula|content=furcula {{anchor|furculae|wishbone|wishbones|wish-bone|wish-bones|merry thought|merry-thought}} }}
{{defn|''Also, '''wishbone'''; '''merry-thought'''.'' From the Latin for "little fork", the furcula is a forked [[Biology:Bone|bone]], also found in some dinosaurs, located below the neck and formed by the fusion of the two [[Biology:Clavicle|clavicle]]s. Its primary function is in the strengthening of the [[Biology:Thorax|thoracic]] skeleton to withstand the rigors of [[Physics:Flight|flight]]. It works as a strut between a bird's shoulders, and articulates to each of a bird's scapulae. In conjunction with the coracoid and the scapula, it forms a unique structure called the triosseal canal, which houses a strong tendon that connects the [[Biology:Bird anatomy#Muscular system|supracoracoideus]] muscles to the [[Biology:Humerus|humerus]]. This system is responsible for lifting the wings during a recovery stroke. As the thorax is compressed by the flight muscles during a downstroke, the upper ends of the furcula spread apart, expanding by as much as 50% of its resting width, and then contract. Furcula may also aid in respiration, by helping to pump air through the [[Biology:Bird anatomy#Respiratory system|air sacs]].<ref name="Gill134-136">{{Harvnb|Gill|1995|pp=134–136}}</ref><ref>{{Cite OED|Furcula}}</ref>}}

{{Glossary end}}

==G==
{{Glossary}}
[[File:House sparrow portrait.jpg|thumb|The {{gli|gape flange}} on this juvenile [[Biology:House sparrow|house sparrow]] is the yellowish region at the base of the beak.]]
{{Term|gape|content=gape {{anchor|gapes}} }}
{{defn|The interior of the open mouth of a bird.<ref name="Newman">{{cite book | title=Newman's birds by colour | first=Kenneth B. | last=Newman | publisher=Struik | year=2000 | page=14 | isbn=978-1-86872-448-2}}</ref> The width of the gape can be a factor in the choice of food.<ref>{{cite magazine|title=Fruit size, gape width and the diets of fruit-eating birds|last1=Wheelwright|first1=NT|volume=66|issue= 3|year=1985|pages=808–818|url=http://www.bowdoin.edu/faculty/n/nwheelwr/pdf/FruitsizeGape.pdf|doi=10.2307/1940542|magazine=Ecology|jstor=1940542|archive-url=https://web.archive.org/web/20160408055802/http://www.bowdoin.edu/faculty/n/nwheelwr/pdf/FruitsizeGape.pdf|archive-date=April 8, 2016|url-status=dead}}</ref>}}

{{Term|gape flange|content=gape flange {{anchor|gape flanges}} }}
{{defn|The region where the {{gli|upper mandible|upper}} and {{gli|lower mandible|lower}} mandibles join together at the base of the {{gli|beak}}.<ref name="Newman"/> When born, the chick's gape flanges are fleshy. As it grows into a {{gli|fledgling}}, the gape flanges remain somewhat swollen and can thus be used to recognize that a particular bird is young.<ref>{{Cite web| url=http://www.birdwatchersdigest.com/site/backyard_birds/bird_Id/mystery_birds.aspx|title=Backyard Mystery Birds| first=Julie | last=Zickefoose | publisher=Bird Watcher's Digest|access-date=January 29, 2017| date=July 25, 2014}}</ref> Gape flanges can serve as a target for food for parents, and when touched, stimulate the nestling to open its mouth to eat.<ref>{{Harvnb|Elphick|2016|p=71}}</ref>}}

{{Term|gizzard|content=gizzard {{anchor|gizzards|ventriculus|ventriculae|koilin|gastric mill|gigerium}} }}
{{Main|Biology:Gizzard}}
{{defn|''Also, '''ventriculus'''; '''gastric mill'''; '''gigerium'''.'' A specialized [[Biology:Stomach|stomach]] organ found in the digestive tract of some birds constructed of thick muscular walls that is used for grinding up food, often aided by particles of stone or grit. Food, after going through the {{gli|crop}} and {{gli|proventriculus}}, passes into the gizzard where it can be ground with previously swallowed stones and passed back to the proventriculus, and vice versa. Bird gizzards are lined with a tough layer made of a carbohydrate-protein complex called koilin, that protects the muscles in the gizzard.<ref name="Pettingill77">{{Harvnb|Pettingill|1985|p=77}}</ref><ref name="Nyakupfuka2013">{{cite book|last=Nyakupfuka|first=Andrew|title=Global Delicacies: Diversity, Exotic, Strange, Weird, Relativism.|url=https://books.google.com/books?id=G7UEER5uKwQC&pg=PA120|date=April 3, 2013|publisher=Balboa Press|isbn=978-1-4525-6791-4|page=120}}</ref>}}

{{Term|gleaning|content=gleaning {{anchor|glean|foliage gleaning|hover-gleaning|crevice-gleaning}} }}
{{Main|Biology:Gleaning (birds)}}
{{defn|''Specialized cases: '''foliage gleaning'''; '''hover-gleaning'''; '''crevice-gleaning'''.'' The strategy of gleaning over surfaces by birds to catch invertebrate prey—chiefly [[Biology:Insect|insect]]s and other [[Biology:Arthropod|arthropod]]s—by plucking them from foliage or the ground, from crevices such as of rock faces and under the eaves of houses, or even, as in the case of ticks and lice, from living animals. Gleaning the leaves and branches of trees and shrubs is called "foliage gleaning", which can involve a variety of styles and maneuvers. Some birds, such as the [[Biology:Common chiffchaff|common chiffchaff]]<ref>{{cite book|last1=Peterson|first1=Roger|last2 = Mountfort|first2=Guy|last3=Hollom|first3=P.A.D.|title=A Field Guide to the Birds of Britain and Europe|publisher=Collins|location = London|year=1954|page=251}}</ref> of [[Biology:Palearctic realm|Eurasia]] and the [[Biology:Wilson's warbler|Wilson's warbler]] of [[Biology:Nearctic realm|North America]], feed actively and appear energetic. Some will even hover in the air near a twig while gleaning from it; this behaviour is called "hover-gleaning". Other birds are more methodical in their approach to gleaning, even seeming lethargic as they perch upon and deliberately pick over foliage. This behaviour is characteristic of the [[Biology:Bay-breasted warbler|bay-breasted warbler]]<ref name="Dunn">{{cite book|last1=Dunn|first1=Jon|last2=Garrett|first2=Kimball|title=Warblers|publisher=[[Software:Peterson Field Guides|Peterson Field Guides]]|location=New York|year=1997|pages = 18, 377, 437, 470, 551|isbn=978-0-395-78321-4}}</ref> and many [[Biology:Vireo|vireo]]s. Another tactic is to hang upside-down from the tips of branches to glean the undersides of leaves. Tits such as the familiar [[Biology:Black-capped chickadee|black-capped chickadee]] are often observed feeding in this manner. Some birds, like the [[Biology:Ruby-crowned kinglet|ruby-crowned kinglet]], use a combination of these tactics. "Crevice-gleaning" is a niche particular to dry and rocky habitats. Gleaning birds are typically small with compact bodies and have small, sharply pointed {{gli|beaks}}. Birds often specialize in a particular niche, such as a particular stratum of forest or type of vegetation.<ref>{{Harvnb|Sibley, et al.|2001|pages=360–361, 377, 390, 404, 427, 435–436, 441, 451, 545}}</ref>}}

{{Term|gnathotheca}}
{{defn|The {{gli|rhamphotheca}} (thin horny sheath of [[Biology:Keratin|keratin]]) covering the {{gli|lower mandible}}.<ref name="Proctor66"/><ref name="Gill148"/><ref name="Campbell47"/>}}

{{Term|gonys}}
{{defn|The ventral ridge of the {{gli|lower mandible}}, created by the junction of the bone's two rami, or lateral plates.<ref name="Campbell254"/>}}

{{Term|gonydeal angle|content=gonydeal angle {{anchor|gonydeal angles|gonydeal-angle|gonydeal-angles|gonydeal expansion|gonydeal expansions|gonydeal-expansion|gonydeal-expansions}} }}
{{defn|''Also, '''gonydeal expansion'''.'' The proximal end of the junction created by the {{gli|gonys}} two rami, or lateral plates—the place where the two plates separate. The size and shape of the gonydeal angle can be useful in identifying between otherwise similar species.<ref name="Howell23">{{Harvnb|Howell|2007|p=23}}</ref>}}

{{Term|gonydeal spot|content=gonydeal spot {{anchor|gonydeal spots|gonydeal-spot|gonydeal-spots}} }}
{{defn|The spot near the gonydeal expansion, in adults of many bird species but especially in gulls, usually reddish or orangish in colour, that triggers begging behaviour. Gull chicks, for example, peck at the spot on its parent's bill, which in turn stimulates the parent to {{gli|regurgitate}} food.<ref name="Howell23"/><ref>{{cite book |last1=Russell |first1=Peter J. |first2=Stephen L. |last2=Wolfe |first3=Paul E. |last3=Hertz |first4=Cecie |last4=Starr |title=Biology: The Dynamic Science |volume=2 |year=2008 |publisher=Thomson Brooks/Cole |location=Belmont, CA |isbn=978-0-495-01033-3 |page=1255}}</ref>}}

[[File:Costa's hummingbird (Calypte costae)-cropped.jpeg|thumb|upright=0.8|Male Costa's hummingbird (''Calypte costae'') with an iridescent {{gli|gorget}}]]
{{Term|gorget|content=gorget {{anchor|gorgets}} }}
{{defn|A patch of coloured feathers found on the throat or upper breast of some species of [[Biology:Bird|bird]]s.<ref name="Campbell254">{{Harvnb|Campbell|Lack|1985|p=254}}</ref> It is a feature found on many male [[Biology:Hummingbird|hummingbird]]s, particularly those found in North America, whose gorgets are typically iridescent.<ref>{{cite book |first=Steve N. G.|last=Howell|title=Hummingbirds of North America: The Photographic Guide|year=2002|publisher=Academic Press|isbn=978-0-12-356955-4|page=1}}</ref> Other species having gorgets include the [[Biology:Purple-throated fruitcrow|purple-throated fruitcrow]]<ref>{{cite book |title=The Birds of South America: The suboscine passerines |first1=Robert S. |last1=Ridgely |first2=Guy |last2=Tudor |first3=William L. |last3=Brown |page=771 |year=1994 |location=Austin, TX |publisher=University of Texas Press |isbn=978-0-292-77063-8}}</ref> and the [[Biology:Chukar partridge|chukar partridge]].<ref>{{cite book |title=The Chukar Partridge: Its Introduction, Life History and Management |first=Glen C. |last=Christensen |page=33 |location=Reno, NV |publisher=Nevada Department of Fish and Game |year=1970}}</ref> The term is derived from the [[Engineering:Gorget|gorget]] used in military armor to protect the throat.<ref>{{Cite podcast|url=http://www.audubon.org/news/a-hummingbirds-shining-armor|title=A Hummingbird's Shining Armor|publisher=BirdNote|work=BirdNote|date=8 April 2015|last=Sundstorm|first=Bob|others=Narrated by Mary McCann}}</ref>}}

{{Term|grooming}}
{{defn|''See entry for {{gli|preening}}.''}}

{{Term|gular region|content=gular region {{anchor|gular|gulars|gula}} }}
{{defn|The posterior part of the underside of a bird's head, described as "a continuation of the chin to an imaginary line drawn between the angles of the jaw".<ref name="Pettingill32"/> ''See also: {{gli|gular skin}}.''}}

{{Term|gular skin|content=gular skin {{anchor|gular|gular sac|gular sacs|gular pouch|gular pouches|throat sac|gular flutter|gular fluttering|gular panting|gular pant}} }}
{{defn|''Also defined, '''gular sac'''&thinsp;/&thinsp;'''throat sac'''; '''gular pouch'''; '''gular flutter'''.'' Describes the {{gli|gular region}} when it is featherless. In many species, the gular skin forms a flap, or ''gular pouch'', which is generally used to store fish and other prey while hunting. In many others, such as frigatebirds, the gular skin may overlie a sac—the ''gular sac'' or ''throat sac''—that may be dramatically inflated by males during courtship display. In some species the gular region is used for thermoregulation, by the fluttering of the [[Biology:Hyoid bone|hyoid bone]] and surrounding muscles, vibrating as many as 735 times per minute, which causes an increase in heat dissipation from the gular skin.<ref name="MorrisPress1992">{{cite book|last1=Morris|first1=Christopher G.|author2=Academic Press|title=Academic Press Dictionary of Science and Technology|url=https://books.google.com/books?id=nauWlPTBcjIC&pg=PA971|year=1992|publisher=Gulf Professional Publishing|isbn=978-0-12-200400-1|page=971}}</ref><ref name="DayRiepe2015">{{cite book|last1=Day|first1=Leslie|last2=Riepe|first2=Don|title=Field Guide to the Neighborhood Birds of New York City|url=https://books.google.com/books?id=EwTHCQAAQBAJ&pg=PT36|year=2015|publisher=JHU Press|isbn=978-1-4214-1617-5|page=36}}</ref><ref name="Lederer2016">{{cite book|last=Lederer|first=Roger|title=Beaks, Bones and Bird Songs: How the Struggle for Survival Has Shaped Birds and Their Behavior|url=https://books.google.com/books?id=v9YlDAAAQBAJ&pg=PT157|year=2016|publisher=Timber Press|isbn=978-1-60469-752-0|page=157}}</ref>}}

{{Glossary end}}

==H==
{{Glossary}}
{{Term|hallux|content=hallux {{anchor|hind toe|hind toes|incumbent hallux|elevated hallux|first digit|incumbent}} }}
{{defn|''Also, '''hind toe'''; '''first digit'''. Specialized types: '''incumbent''' and '''elevated'''.'' A bird's usually rear-facing toe; its ''hind toe''. When it is attached near the base of the {{gli|tarsometatarsus|metatarsus}} it is termed ''incumbent'', and when projecting from a higher portion of the metatarsus (as in [[Biology:Rail (bird)|rails]]), it is termed ''elevated''. The hallux is a bird's ''first digit'', in many birds being the sole rear-facing toe (including in most {{gli|passerine}} species that have {{gli|anisodactylous}} feet) and is homologous to the human big toe.{{sfn|Lovette|Fitzpatrick|2016|p=181}}<ref>{{Harvnb|Feduccia|1999|p=13}}</ref><ref>{{Harvnb|Bird|2004|p=4}}</ref>}}

{{Term|home range|content=home range {{anchor|territory|territories|temporary territory|permanent territory|breeding territory|non-breeding territory|home ranges|homerange|homeranges|home-range|home-ranges}} }}
{{defn|''Also defined: '''territory'''.'' The area of land in which a bird performs most of its activities. When the area is guarded (in whole or in part) from individuals of the same species it is called a ''territory''.<ref name="OdumKuenzler1955">{{cite magazine|last1=Odum|first1=Eugene P.|last2=Kuenzler|first2=Edward J.|title=Measurement of territory and home range size in birds|magazine=The Auk|volume=72|issue= 2|year=1955|pages=128–137|issn=0004-8038|doi=10.2307/4081419|jstor=4081419}}</ref> These territories may be temporary or permanent, breeding or non-breeding. Breeding territories may be of four types: i) an all-purpose territory where all activities are conducted; ii) a separate breeding and feeding territory (or just a breeding territory, with foraging conducted outside of it); iii) a territory surrounding the nest and a very small area outside of it; iv) a small territory used solely for display within a {{gli|lek}}.<ref name="Elphick135-136">{{harvnb|Elphick|2016|pp=135–136}}</ref> The size of the home range can be affected by what food a bird eats and how much the bird weighs. Birds that weigh more usually have larger ranges, and {{gli|carnivores}} on average have larger ranges than non-carnivores.<ref name="HarestadBunnel1979">{{cite magazine|last1=Harestad|first1=A. S.|last2=Bunnel|first2=F. L.|title=Home range and body weight--a reevaluation|magazine=Ecology|volume=60|issue= 2|year=1979|pages=389–402|issn=0012-9658|doi=10.2307/1937667|jstor=1937667}}</ref>}}

{{Term|Humphrey–Parkes terminology}}
{{Main|Biology:Humphrey–Parkes terminology}}
{{defn|A system of [[Social:Nomenclature|nomenclature]] for the {{gli|plumage}} of birds proposed in 1959 by Philip S. Humphrey and Kenneth C. Parkes<ref name="Humphrey–Parks" /> to make the terminology for describing bird plumages more uniform.<ref>{{Harvnb|Pettingill|1985|pp=98, 190}}</ref> ''Examples of Humphrey–Parkes terminology versus traditional terminology may be seen in the entries for {{gli|prealternate moult}} and {{gli|prebasic moult}}.''}}

{{Term|hyoid apparatus|content=hyoid apparatus {{anchor|hyoid apparatuses|tongue bone|basihyal|urohyal|ceratobranchial|epibranchial}} }}
{{defn|The system of bones to which the tongue is attached. It usually includes the tongue bone, to which the tongue is actually attached,<ref name="Elphick25-6">{{Harvnb|Elphick|2016|pp=25–26}}</ref> the basihyal, behind the tongue bone, the urohyal, itself behind the basihyal, a pair of ceratobranchial bones, and a pair of epibranchial.<ref name="JungNaleway2016">{{cite magazine|last1=Jung|first1=Jae-Young|last2=Naleway|first2=Steven E.|last3=Yaraghi|first3=Nicholas A.|last4=Herrera|first4=Steven|last5=Sherman|first5=Vincent R.|last6=Bushong|first6=Eric A.|last7=Ellisman|first7=Mark H.|last8=Kisailus|first8=David|last9=McKittrick|first9=Joanna|title=Structural analysis of the tongue and hyoid apparatus in a woodpecker|magazine=Acta Biomaterialia|volume=37|year=2016|pages=1–13|issn=1742-7061|doi=10.1016/j.actbio.2016.03.030|pmid=27000554|pmc=5063634}}</ref> The latter two bones form the hyoid horns, which are contained in a pair of fascia vaginalis. This allows the tongue to slide out smoothly. The hyoid apparatus is attached to the larynx.<ref name="Elphick25-6"/>}}
{{Glossary end}}

==I==
{{Glossary}}
{{Term|inferior umbilicus|content=inferior umbilicus {{anchor|inferior umbilicae|proximal umbilicae|proximal umbilicae}} }}

{{Term|inner wing|content=inner wing {{anchor|inner wings|outer wing|outer wings|innerwing|innerwings|outerwing|outerwings}} }}
{{defn|''Also defined: '''outer wing'''.'' The ''inner wing'' of a bird is that portion of the wing stretching from its connection to the body and through the "wrist" joint. The ''outer wing'' stretches from the wrist to the wingtip.<ref name="Scott43">{{Harvnb|Scott|2010|p=43}}</ref>}}

{{Term|iris|content=iris {{anchor|irises}} }}
{{defn|The coloured outer ring that surrounds a bird's {{gli|pupil}}. Though brown predominates, the iris may be of or include a variety of colours—red, yellow, grey, blue, etc.—and the colouration may vary according to the age, sex and species.<ref name="Jasper">{{cite book|last=Jasper|first=Theodore|title=Studer's Popular Ornithology …|url=https://books.google.com/books?id=WvI0AQAAMAAJ&pg=PP24|year=1878|publisher=J.H. Studer & Company|location=Columbus, OH|page=2}}</ref>}}

{{Glossary end}}

==J==
{{Glossary}}
{{Term|jizz|content=jizz {{anchor|gestalt}} }}
{{defn|''Also, '''gestalt''',''<ref name="Zimmer2000">{{cite book|last=Zimmer|first=Kevin J.|title=Birding in the American West: A Handbook|url=https://books.google.com/books?id=TMtB8CG767EC&pg=PA47|year=2000|publisher=Cornell University Press|isbn=978-0-8014-8328-8|page=47}}</ref> of which the term may be a corruption<ref>{{cite magazine|magazine=Canberra Bird Notes|volume=21|issue= 1|title=The Etymology of Jizz|last1=McDonald|first1=David|url=https://www.scribd.com/doc/16209649/The-etymology-of-jizz|date=March 1996|pages=2–11}}</ref> (or possibly deriving from the {{wipe|Air force}} acronym GISS for "General Impression of Size and Shape (of an aircraft)", associated with [[Social:World War II|World War II]] lingo; though this derivation may by anachronistic as ''jizz'' was first used in birdwatching as early as 1922),<ref>{{Cite OED|Jizz}}</ref> it describes the overall impression or appearance of a [[Biology:Bird|bird]]—"the indefinable quality of a particular species, the 'vibe' it gives off"<ref>{{cite book|first=Sean|last=Dooley|title=The Big Twitch|page=78|year=2005|publisher=Allen & Unwin|isbn=978-1-74114-528-1}}</ref>—garnered from such features as shape, posture, flying style or other habitual movements, size and colouration combined with voice, habitat and location.<ref name="Madden2011">{{cite book|author=Dave Madden|title=The Authentic Animal: Inside the Odd and Obsessive World of Taxidermy|url=https://books.google.com/books?id=Uf11AjcpIpMC&pg=PA127|date=August 2, 2011|publisher=St. Martin's Press|isbn=978-1-4299-8762-2|pages=127–}}</ref><ref name="Harrop2004">{{cite book|author=Hugh Harrop|title=Shetland sea mammal report 2003|url=https://books.google.com/books?id=Ex0XAQAAIAAJ|year=2004|publisher=Shetland Sea Mammal Group}}</ref><ref name="Tyzack2013">{{cite book|author=Andrew Tyzack|title=Drawing and Painting Insects|url=https://books.google.com/books?id=HIR8AwAAQBAJ&pg=PT147|date=June 30, 2013|publisher=Crowood Press, Limited|isbn=978-1-84797-625-3|pages=147–}}</ref> ''Example use'': "It had the jizz of a thrush, but I couldn't make out what kind."}}

{{Glossary end}}

==K==
{{Glossary}}
{{Term|keel|content=keel {{anchor|keels|carina|carinum}} }}
{{defn|''Also, '''carina'''.'' An extension of the [[Biology:Sternum|sternum]] (breastbone) which runs axially along the midline of the sternum and extends outward, perpendicular to the plane of the [[Biology:Rib|rib]]s.  The keel provides an anchor to which a bird's wing muscles attach, thereby providing adequate [[Engineering:Lever|lever]]age for {{gli|flight}}.  Keels do not exist on all birds; in particular, some flightless birds lack a keel structure. Historically, the presence or absence of a pronounced keel structure was used as a broad classification of birds into two orders: [[Biology:Carinatae|Carinatae]] (from Latin ''carina'', 'keel'), having a pronounced keel; and [[Biology:Ratite|ratite]]s (from Latin ''ratis'', 'raft'—referring to the flatness of the sternum), having a subtle keel structure or lacking one entirely.  However, this classification has fallen into disuse as evolutionary studies have shown that many flightless birds have evolved from flighted birds.<ref>{{cite web|last=Cummins|first=Jim|date=April 1, 1996|url=http://numbat.murdoch.edu.au/Anatomy/avian/avian2.html|title=Anatomy of Flight|access-date=March 14, 2017|url-status=bot: unknown|archive-url=https://web.archive.org/web/20050211095240/http://numbat.murdoch.edu.au/Anatomy/avian/avian2.html|archive-date=February 11, 2005}}</ref><ref>{{cite web|last=Ramel|first=Gordon|url=http://www.earthlife.net/birds/anatomy.html|title=The Anatomy of Birds|publisher=Earth-Life Web Productions|access-date=March 14, 2017}}</ref>}}

{{Term|kleptoparasitism|content=kleptoparasitism {{anchor|kleptoparasite}} }}
{{Main|Biology:Kleptoparasitism}}
{{defn|A bird's propensity to steal food from other birds, either opportunistically, or on a regular basis.<ref name="Elphick129">{{harvnb|Elphick|2016|p=129}}</ref>}}

{{Glossary end}}

==L==
{{Glossary}}
{{Term|lateral throat-stripe|content=lateral throat-stripe {{anchor|lateral throat-stripes|lateral throat stripe|lateral throat stripes}} }}
{{defn| A usually dark stripe of colour bordering the throat below both the {{gli|moustachial stripe}} and the {{gli|submoustachial stripe}}, if any.<ref name="Vinicombe15"/>}}

{{Term|lek|content=lek {{anchor|leks|lekking|lek mating|lek matings|lek polygyny|exploded lek|exploded leks|dispersed lek|dispersed leks}} }}
{{Main|Biology:Lek mating}}
{{defn|''Also defined: '''lekking'''; '''dispersed lek'''.'' An aggregation of male birds gathered to engage in competitive displays (known as ''lekking'') that may entice visiting females that are assessing prospective partners for copulation.<ref name="Fiske">{{cite magazine|last1=Fiske|first1=Peder|last2=Rintamäki|first2=Pekka T.|last3=Karvonen |first3=Eevi|date= January 1998|title=Mating success in lekking males: a meta-analysis|magazine=Behavioral Ecology|volume=9|issue= 4|pages=328–338|doi=10.1093/beheco/9.4.328|doi-access=free}}</ref> These males are usually in sight of each other, but when they are only in earshot, it is called a ''dispersed lek'' or an ''exploded lek''. Mating usually occurs on the display area.<ref name="Elphick151">{{Harvnb|Elphick|2016|p=151}}</ref>}}

{{Term|lore|content=lore {{anchor|lores|loreal}} }}
{{defn|''Adj. form: '''loreal'''.'' The {{gli|topography|topographical}} region of a bird's head between the eye and the {{gli|beak}} on the sides of the head.<ref name="Pettingill9">{{Harvnb|Pettingill|1985|p=9}}</ref>}}

{{Term|lower mandible}}
{{defn|''Also, '''mandible'''.'' The lower part of a bird's {{gli|bill}} or beak, roughly corresponding to the lower jaw of mammals, it is supported by a bone known as the inferior maxillary bone—a compound bone composed of two distinct ossified pieces. These ossified plates (or rami), which can be U-shaped or V-shaped,<ref name="Coues"/> join distally (the exact location of the joint depends on the species) but are separated [[Biology:Anatomical terms of location#Proximal and distal|proximally]], attaching on either side of the head to the quadrate bone. The jaw muscles, which allow the bird to close its beak, attach to the proximal end of the lower mandible and to the bird's skull.<ref name="Gill148"/>  The muscles that depress the lower mandible are usually weak, except in a few birds such as the starlings (and the extinct [[Biology:Huia|Huia]]), which have well-developed [[Medicine:Digastric muscle|digastric muscle]]s that aid in foraging by prying or gaping actions.<ref>{{cite magazine|last1=Mayr|first1=Gerald |year=2005|title= A new eocene Chascacocolius-like mousebird (Aves: Coliiformes) with a remarkable gaping adaptation| magazine= Organisms, Diversity & Evolution |volume=5|issue= 3 |pages=167–171 | url=http://www.senckenberg.de/files/content/forschung/abteilung/terrzool/ornithologie/chascacocolius.pdf |doi=10.1016/j.ode.2004.10.013}}</ref> In most birds, these muscles are relatively small as compared to the jaw muscles of similarly sized mammals.<ref>{{cite book |title=The Inner Bird: Anatomy and Evolution |first1=Gary W. |last1=Kaiser |publisher=UBC Press |location=Vancouver, BC |page=19 |year=2007 |isbn=978-0-7748-1343-3}}</ref> The outer surface is covered in thin horny sheath of [[Biology:Keratin|keratin]] called {{gli|rhamphotheca}},<ref name="Proctor66"/><ref name="Gill148"/> specially called {{gli|gnathotheca}} in the lower mandible.<ref name="Campbell47"/> ''Compare: {{gli|upper mandible}}.''}}

{{Glossary end}}

==M==
{{Glossary}}

[[File:Preening bird (Unsplash).jpg|thumb|Barn Swallow {{gli|preening}}; one of many {{gli|maintenance behaviours}}|alt=Bird with a wing outstretched, rearranging feathers with the tip of its bill]]
{{Term|maintenance behaviour|content=maintenance behaviour {{anchor|maintenance behaviours|maintenance behavior|maintenance behaviors|comfort behaviour|comfort behavior|comfort behaviours|comfort behaviors}} }}
{{defn|''Also, '''comfort behaviour'''.'' The name given to any behaviour or activity which a bird uses to maintain its plumage and soft parts: {{gli|preening}}, bathing, {{gli|anting}}, sunbathing, stretching, scratching, and other such activities.<ref>{{cite book |first1=Donald W. |last1=Stokes |first2=Lillian Q. |last2=Stokes |name-list-style=amp |title=Stokes Backyard Bird Book |location=Emmaus, PA |publisher=Rodale |year=2003 |isbn=1-57954-864-4 |page=141}}</ref>{{sfn|Campbell|Lack|1985|p=101}} Roosting is also often considered to be a comfort behaviour.{{sfn|Campbell|Lack|1985|pp=101-105}} The phrase is sometimes used more inclusively, to describe ''all'' life-sustaining activities, such as feeding, drinking, predator avoidance, and locomotion,{{sfn|Sibley, et al.|2001|pp=55–59}} and even involuntary biological processes, like {{gli|moulting}}.<ref name="Kricher2020">{{cite book|last=Kricher|first=John|title=Peterson Reference Guide to Bird Behavior|url=https://books.google.com/books?id=Lce_DwAAQBAJ&pg=PA20|year=2020|publisher=Houghton Mifflin Harcourt|page=20|isbn=978-1-328-78736-1}}</ref>}}

{{Term|mandible}}
{{defn|In birds, the word ''mandible'', alone, usually refers to the {{gli|lower mandible}}.}}

{{Term|mantle}}
{{defn|The forward area of a bird's upper side sandwiched between the {{gli|nape}} and the start of the {{gli|back}}. However, in [[Biology:Gull|gull]]s and [[Biology:Tern|tern]]s, the term is often used to refer to much of the upper surface below the nape.<ref name="Vinicombe15">{{Harvnb|Vinicombe|2014|p=15}}</ref>}}

{{Term|migration|content=migration {{anchor|migrations|migratory|partial migration|partially migratory|seasonal migration|seasonal migrations}} }}
{{defn|''Also defined: '''partial migration'''.'' The regular seasonal movement, often north and south, undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat, or weather. Sometimes journeys are not termed "true migration" because they are irregular (nomadism, invasions, irruptions) or only in one direction (dispersal, movement of young away from natal areas). Migration is marked by its annual seasonality.<ref name="Pettingill232–234">{{Harvnb|Pettingill|1985|pages=232–234}}</ref><ref name="Berthold">{{cite book|title=Bird Migration: A General Survey |last1=Berthold|first1=Peter |last2=Bauer|first2=Hans-Günther|last3=Westhead|first3=Valerie|year=2001|isbn=978-0-19-850787-1|publisher=Oxford University Press| location=Oxford}}</ref> Non-migratory birds are said to be {{gli|resident}} or sedentary. Approximately 1,800 of the world's bird species are long-distance migrants.<ref name="Seker">{{cite magazine|title=Conservation ecology: area trumps mobility in fragment bird extinctions|last=Sekercioglu|first=C.H.|magazine=Current Biology|year=2007|volume=17|issue= 8|pages=283–286|doi=10.1016/j.cub.2007.04.045|pmid=1743770|doi-access=free}}</ref><ref name=Rolland>{{cite magazine|title=Settling down of seasonal migrants promotes bird diversification|last1=Rolland|first1=Jonathan|last2=Jiguet|first2=Frédéric|last3=Jønsson|first3=Knud Andreas|last4=Condamine|first4=Fabien L.|last5=Morlon|first5=Hélène|magazine=Proceedings of the Royal Society B|year=2014|volume=281|issue= 1784|pages=20140473|doi=10.1098/rspb.2014.0473|pmid=24759866|pmc=4043101}}</ref> Many bird populations migrate long distances along a flyway. The most common pattern involves flying north in the northern spring to breed in the temperate or Arctic summer, and returning in the autumn to wintering grounds in warmer regions to the south. In the southern hemisphere the directions are reversed, but there is less land area in the far south to support long-distance migration.<ref name=newton>{{cite book|last=Newton|first=Ian|year=2008|title=The Migration Ecology of Birds|publisher= Elsevier|isbn=978-0-12-517367-4}}</ref> Not all populations within a species may be migratory; this is known as "partial migration".  Partial migration is very common in birds of the southern continents. For example, in Australia, 44% of non-passerine birds and 32% of {{gli|passerine}} species are partially migratory.<ref>{{cite magazine|last1=Chan|first1=Ken|date=January 2001|title=Partial migration in Australian landbirds: a review|magazine=Emu|volume=101|issue= 4|pages=281–292|doi=10.1071/MU00034}}</ref> Many, if not most birds migrate in flocks. For larger birds, flying in flocks reduces the energy cost, e.g., geese in a V-formation may conserve 12–20% of the energy they would otherwise need if flying alone.<ref>{{cite magazine|last1=Hummel|first1=D.|last2=Beukenberg|first2=M.|year=1989|title=Aerodynamische Interferenzeffekte beim Formationsfl ug von Vogeln|magazine=J. Ornithol.|volume=130|pages=15–24|doi=10.1007/BF01647158}}</ref><ref>{{cite magazine|last1=Cutts|first1=C. J.|last2=Speakman|first2=J. R.|year=1994 |title=Energy savings in formation flight of Pink-footed Geese|magazine=J. Exp. Biol.|volume=189|pages=251–261|url=http://jeb.biologists.org/cgi/reprint/189/1/251.pdf|pmid=9317742| issue= 1}}</ref>}}

{{Term|morph|content=morph {{anchor|morphs|color morph|color morphs|color-morph|color-morphs|colour morph|colour morphs|colour-morph|colour-morphs}} }}
{{defn|''Also, ''' colour/color morph'''.'' [[Biology:Polymorphism|Polymorphic]] variance in the colouring of the plumage between individuals of the same species, unrelated to age, sex or season. For example, the [[Biology:Snow goose|snow goose]] has two plumage morphs, white (snow) or grey/blue (blue), thus the common description of individuals as either "snows" or "blues". At one time this colour morph resulted in the "blue goose" being classified as a separate species.<ref>{{cite magazine|author=Laboratory of Ornithology, Cornell University|title=Scheduled Birding Trips Around the State Join Newell|url=https://books.google.com/books?id=RTclAQAAMAAJ|date=March 1974|magazine=Scissortail|page=32|issn=0582-2637|volume=24}}</ref><ref name="BeedyPandolfino2013">{{cite book|last1=Beedy|first1=Ted|last2=Pandolfino|first2=Ed|title=Birds of the Sierra Nevada: Their Natural History, Status, and Distribution|url=https://books.google.com/books?id=lALkK5pRuFUC&pg=PA47|year=2013|publisher=University of California Press|isbn=978-0-520-95447-2|page=47}}</ref>}}

{{Term|moult|content=moult {{anchor|moults|molt|molts|moulting|moultings|molting|moltings|wing moult|wing molt|wing moults|wing molts|feather moult|feather moulting|feather molt|feather molting}} }}
{{defn|''Also, '''molt''''' (chiefly U.S.) and '''''moulting'''&thinsp;/&thinsp;'''molting'''.'' The periodic replacement of feathers by shedding old feathers while producing new ones. Feathers are dead structures at maturity which are gradually abraded and need to be replaced. Adult birds moult at least once a year, although many moult twice and a few three times each year. It is generally a slow process, as birds rarely shed all their feathers at any one time; the bird must retain sufficient feathers to regulate its [[Physics:Thermoregulation|body temperature]] and repel moisture. The number and area of feathers that are shed varies. In some moulting periods, a bird may renew only the feathers on the head and body, shedding the wing and tail feathers during a later moulting period. Some species of bird become flightless during an annual "wing moult" and must seek a protected habitat with a reliable food supply during that time. Typically, a bird begins to shed some old feathers, then pin feathers grow in to replace the old feathers. As the pin feathers become full feathers, other feathers are shed. This is a cyclical process that occurs in many phases. It is usually symmetrical, with feather loss equal on each side of the body. Because feathers make up 4–12% of a bird's body weight, it takes a large amount of energy to replace them. For this reason, moults often occur immediately after the breeding season, but while food is still abundant. The plumage produced during this time is called {{gli|postnuptial plumage}}.<ref name="Terres616-617">{{harvnb|Terres|1980|pp=616–617}}</ref>}}

{{Term|moult strategy|content=moult strategy {{anchor|moulting strategy|moult strategies|moulting strategies|complex alternate strategy|complex basic strategy|simple alternate strategy|simple basic strategy|molt strategy|molt strategies|molting strategy|molting strategies}} }}
{{defn|''Specialized types defined: '''simple basic strategy'''; '''simple alternate strategy'''; '''complex basic strategy'''; '''complex alternate strategy'''.'' The pattern of {{gli|moults}} that occurs regularly based on the season and time. There are four main moulting strategies: i) simple basic strategy, in which there is one moult per year, every year; ii) simple alternate strategy, in which there are two moults per year, every year; iii) complex basic strategy, in which there is one moult per year, except in the first year of life, where there is an additional moult; and iv) complex alternate strategy, in which there are two moults per year, except in the first year of life, where there is an additional moult.<ref>{{harvnb|Floyd|2008|p=497}}</ref>}}

[[File:New Zealand Pipit Kapiti-Moustachial stripe.jpeg|thumb|upright=0.8|New Zealand pipit ''Anthus novaeseelandiae novaeseelandiae'', displaying a prominent {{gli|moustachial stripe}}]]
{{Term|moustachial stripe|content=moustachial stripe {{anchor|mustachial stripes|mustachial stripes|moustachial stripes|moustachial-stripe|moustachial-stripes|mustache stripe|mustache stripes|malar stripe|malar stripes}} }}
{{defn|''Also, '''mustache stripe'''; '''whisker stripe'''; '''malar stripe'''.'' A dark feather colouration line running "obliquely from the {{gli|gape}} down and along the lower border of the {{gli|ear-coverts}}". ''Compare: {{gli|submoustachial stripe}} and {{gli|lateral throat-stripe}}.''<ref name="Vinicombe15"/> Birds with moustachial stripes include some of the pipits as well as buntings.<ref name="Vinicombe15"/>}}

{{Glossary end}}

==N==
{{Glossary}}

[[File:Lesser Whistling Duck (Dendrocygna javanica), Singapore -cropped.jpg|thumb|Close up of a [[Biology:Lesser whistling duck|lesser whistling duck]]. Note the hooked {{gli|nail}} at the tip of the beak.]] 
{{Term|nail|content=nail {{anchor|nail|nail (beak)|nail (of beak)|nail of the beak}} }}
{{defn|A plate of hard horny tissue at the tip of the beak of all birds in the family [[Biology:Anatidae|Anatidae]] (ducks, geese and swans).<ref>{{Harvnb|King|McLelland|1985|p=376}}</ref> This [[Engineering:Shield|shield]]-shaped structure, which sometimes spans the entire width of the beak, is often bent at the tip to form a hook.<ref name="Elliot">{{cite book |title=The Wild Fowl of the United States and British Possessions |first=Daniel Giraud |last=Elliot |publisher= F. P. Harper |year=1898 |location=New York, NY |page=xviii |lccn=98001121|url=https://archive.org/details/wildfowluniteds00elligoog }}</ref> It serves different purposes depending on the bird's primary food source. Most species use their nails to dig seeds out of mud or vegetation,<ref>{{cite book |title=Birds |first=Christopher M. |last=Perrins |year=1974 |publisher=Collins |location=London, UK |isbn=978-0-00-212173-6 |page=24}}</ref> while [[Biology:Diving duck|diving duck]]s use theirs to pry [[Biology:Mollusc|mollusc]]s from rocks.<ref>{{cite book |title=Why Ducks Do That: 40 Distinctive Duck Behaviors Explained and Photographed |first=Chuck |last=Petrie |year=2006 |publisher=Willow Creek Press |location=Minocqua, WI |isbn=978-1-59543-050-2 |page=31}}</ref> There is evidence that the nail may help a bird to grasp things; species which use strong grasping motions to secure their food (such as when catching and holding onto a large squirming frog) have very wide nails.<ref>{{cite book |title=Functional Anatomy of the Feeding Apparatus in Waterfowl (Aves:Anatidae) |last1=Goodman |first1=Donald Charles |first2=Harvey I. |last2=Fisher |publisher=Southern Illinois University Press |location=Carbondale, IL |year=1962 |oclc=646859135 |page=179}}</ref> Certain types of [[Philosophy:Mechanoreceptor|mechanoreceptor]]s, nerve cells that are sensitive to pressure, vibration or touch, are located under the nail.<ref>{{Harvnb|King|McLelland|1985|p=421}}</ref>}}

{{Term|nares|content=nares {{anchor|nostril|nostrils}} }}
{{defn|The two holes—circular, oval or slit-like in shape—which lead to the nasal cavities within the bird's skull, and thus to the rest of the [[Biology:Bird anatomy#Respiratory system|respiratory system]].<ref name="Campbell375"/> In most bird species, the nares are located in the basal third of the upper mandible. [[Biology:Kiwi (bird)|Kiwi]]s are a notable exception; their nares are located at the tip of their bills.<ref name="Stettenheim"/> A handful of species have no external nares. [[Biology:Cormorant|Cormorant]]s and [[Biology:Darter|darter]]s have primitive external nares as nestlings, but these close soon after the birds [[Biology:Fledge|fledge]]; adults of these species (and gannets and boobies of all ages, which also lack external nostrils) breathe through their mouths. There is typically a septum made of bone or cartilage that separates the two nares, but in some families (including gulls, cranes and New World vultures), the septum is missing. While the nares are uncovered in most species, they are covered with feathers in a few groups of birds, including [[Biology:Grouse|grouse]] and [[Biology:Lagopus|ptarmigans]], [[Biology:Corvus|crows]] and some [[Biology:Woodpecker|woodpecker]]s.<ref name="Campbell375"/>}}

{{Term|nasal canthus|content=nasal canthus {{anchor|nasal canthi||canthi|canthus}} }}
{{defn|The area where the eyelids come together at the anterior corner of the eye, on the side of the {{gli|nares}}, as opposed to the {{gli|temporal canthus}}.<ref name="Pettingill10"/>}}

{{Term|natal down|content=natal down {{anchor|natal-down|natal down feather|natal down feathers|natal-down feathers|neossoptiles|protoptile|protoptiles|mesoptile|mesoptiles}} }}
{{defn|''Also, '''neossoptiles'''. Also defined: '''protoptiles'''; '''mesoptiles'''.'' The layer of {{gli|down}} feathers that cover most birds at some point in their early development. Precocial nestlings are already covered with a layer of down when they hatch, while altricial nestlings develop their down layer within days or weeks of hatching. [[Biology:Megapode|Megapode]] hatchlings are the sole exception; they are already covered with contour feathers when they hatch.<ref>{{Harvnb|Campbell|Lack|1985|p=470}}</ref> The natal down coat is usually lost within a week or two of hatching.<ref name="Gill108"/> There are two different kinds of natal down feathers; protoptiles and mesoptiles.<ref name="Hosker1936">{{cite magazine| issn = 0080-4622| volume=226| issue= 533| pages = 143–188| last = Hosker| first = Anne| title = Studies on the epidermal structures of birds| magazine = Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences| date = 1936| jstor = 92253| doi = 10.1098/rstb.1936.0006| bibcode = 1936RSPTB.226..143H| doi-access = free}}</ref> The former appears first<ref>{{harvnb|Bird|2004|p=281}}</ref> and the latter appears second.<ref>{{harvnb|Bird|2004|p=277}}</ref> Hathchlings born naked or with a diffuse coat of scant natal down feathers are called {{gli|psilopaedic}}, while those born covered with a dense fuzz of natal down are termed {{gli|ptilopaedic}}.<ref name="Gill108">{{Harvnb|Gill|1995|p=108}}</ref> ''Compare: {{gli|body down}} and {{gli|powder down}}''.}}

[[File:Nests.svg|thumb|upright=2|An overview of the diversity in nest placement and construction]]
{{Term|nest|content=nest {{anchor|nests|birdnest|bird nest|birdnests|bird nests|burrow|cavity|cup| dormitory|eyries|aeries|mound|pendant|platform|roost|winter|scrape|saucer|plate |sphere|burrows|cavities|cups|dormitories|mounds|pendants|platforms|roosts|winters|scrapes|saucers|plates|spheres|statant|statant cup|adherent cup|hanging}} }}
{{defn|''Also, '''bird nest'''. Specialized types: '''burrow'''; '''cavity'''; '''cup''' ('''adherent cup'''; '''statant cup'''); '''dome'''; '''dormitory'''; '''eyries''' (or '''aeries'''); '''hanging'''; '''ledge'''; '''mound'''; '''pendant'''; '''platform'''; '''roost''' (or '''winter-nest'''); '''scrape'''; '''saucer''' or '''plate'''; and '''sphere'''.'' The spot in which a bird lays and incubates its eggs and raises its young. Although the term popularly refers to a specific structure made by the bird itself—such as the grassy cup nest of the [[Biology:American robin|American robin]] or Eurasian blackbird, or the elaborately woven hanging nest of the [[Biology:Montezuma oropendola|Montezuma oropendola]] or the [[Biology:Village weaver|village weaver]]—for some species, a nest is simply a shallow depression made in sand; for others, it is the knot-hole left by a broken branch, a burrow dug into the ground, a chamber drilled into a tree, an enormous rotting pile of vegetation and earth, a shelf made of dried saliva or a mud dome with an entrance tunnel. The smallest bird nests are those of some [[Biology:Hummingbird|hummingbird]]s, tiny cups which can be a mere {{convert|2|cm|in|abbr=on}} across and {{convert|2|–|3|cm|in|abbr=on}} high.<ref name="Campbell386">{{Harvnb|Campbell|Lack|1985|p=386}}</ref> At the other extreme, some nest mounds built by the dusky scrubfowl measure more than {{convert|11|m|ft|abbr=on}} in diameter and stand nearly {{convert|5|m|ft|abbr=on}} tall.<ref>{{Harvnb|Campbell|Lack|1985|p=345}}</ref> Not all bird species build nests. Some species lay their eggs directly on the ground or rocky ledges, while brood parasites lay theirs in the nests of other birds, letting unwitting "foster parents" do all the work of rearing the young. Although nests are primarily used for breeding, they may also be reused in the non-breeding season for roosting and some species build special dormitory nests or roost nests (or winter-nest) that are used only for roosting.<ref name=skutch>{{cite magazine|title=The nest as a dormitory|last=Skutch |first=Alexander F|magazine=Ibis| volume=103| issue= 1 | pages=50–70 | doi=10.1111/j.1474-919X.1961.tb02420.x| year=1960}}</ref> Most birds build a new nest each year, though some refurbish their old nests.<ref>{{cite web|last=Gibbon|first=Johnny|publisher=Smithsonian|title=Bird Nests: Variety Is Key For The World's Avian Architects|url=http://smithsonianscience.org/2015/04/bird-nests-variety-is-key-for-avian-architects|date=April 20, 2015|archive-url=https://web.archive.org/web/20170103173244/http://insider.si.edu/2015/04/bird-nests-variety-is-key-for-avian-architects/|archive-date=January 3, 2017|access-date=February 7, 2017|url-status=dead}}</ref> The large eyries (or aeries) of some eagles are platform nests that have been used and refurbished for several years. In most species, the female does most or all of the nest construction, though the male often helps.<ref>{{Harvnb|Campbell|Lack|1985|p=387}}</ref> The nest may form a part of the courtship display, such as in [[Biology:Ploceidae|weaver birds]].<ref name="Elphick151"/>}}

[[File:Bird blink-edit.jpg|thumb|The {{gli|nictitating membrane}} as it covers the eye of a masked lapwing]]
{{Term|nictitating membrane|content=nictitating membrane {{anchor|nictitating membranes|nictitating|third eyelid}} }}
{{defn|''Also, '''third eyelid'''.'' A transparent or translucent third [[Biology:Eyelid|eyelid]] that is drawn across the eye for protection, to moisten it while maintaining vision.<ref>{{cite magazine|last1=Williams |first1=David L. |date=March 2003 |title=Symblepharon with aberrant protrusion of the nictitating membrane in the snowy owl (''Nyctea scandiaca'') |magazine=Veterinary Ophthalmology |volume=6 |issue= 1 |pages=11–13 |doi=10.1046/j.1463-5224.2003.00250.x |pmid=12641836 |last2=Flach |first2=E}}</ref> The nictitating membrane also covers the eye and acts as a [[Engineering:Contact lens|contact lens]] in many aquatic birds.<ref name="Gill185">{{Harvnb|Gill|1995|p=185}}</ref> With the exception of pigeons and a few other species, most birds blink only with their nictitating membrane, and when not sleeping, use the eyelids chiefly only when the eye is threatened with some foreign matter.<ref name="Pettingill11">{{Harvnb|Pettingill|1985|page=11}}</ref>}}

{{Term|nidicolous|content=nidicolous}}
{{Main|Biology:Nidicolous}}
{{defn|Young that remain in their nest after hatching for an extended period of time and thus must be {{gli|dietary classification terms (-vores)|fed}} by their parents.<ref name="Pettingill371"/> ''Contrast: {{gli|nidifugous}}''.}}

{{Term|nidifugous|content=nidifugous}}
{{Main|Biology:Nidifugous}}
{{defn|Young that leave the nest soon after hatching, joining their parents in {{gli|foraging}}.<ref name="Pettingill371"/> ''Contrast: {{gli|nidicolous}}''.}}

{{Term|non-breeding plumage}}
{{defn|''See {{gli|basic plumage}}.''}}

{{Term|notch|content=notch {{anchor|notches}} }}
{{defn|A pronounced narrowing at some variable distance along the feather edges at the outermost {{gli|primaries}} of large soaring birds, particularly raptors. Whether these narrowings are called notches or {{gli|emarginations}} depends on the degree of their slope.<ref name="Campbell656"/> An emargination is a gradual change, and can be found on either side of the feather. A notch is an abrupt change, and is only found on the wider trailing edge of the remiges. The presence of notches and emarginations creates gaps at the wingtip; air is forced through these gaps, increasing the generation of lift.<ref name="Trail6"/>}}

{{Term|nuptial plumage}}
{{defn|''See {{gli|alternate plumage}}.''}}

{{Glossary end}}

==O==
{{Glossary}}
{{Term|oology|content=oology {{anchor|oologist}} }}
{{Main|Biology:Oology}}
{{defn|The scientific study of eggs.<ref name="Hauber2014">{{cite book|last=Hauber|first=Mark E.|title=The Book of Eggs: A Life-Size Guide to the Eggs of Six Hundred of the World's Bird Species|url=https://books.google.com/books?id=evQvBAAAQBAJ|date=1 August 2014|publisher=University of Chicago Press|location=Chicago|isbn=978-0-226-05781-1|page=31}}</ref>}}

{{Term|operculum|content=operculum {{anchor|opercula}} }}
{{defn|''Plural: '''opercula'''.'' A membraneous, horny or [[Biology:Cartilage|cartilaginous]] flap covering the {{gli|nares}} of some birds.<ref name="Gill117">{{Harvnb|Gill|1995|p=117}}</ref><ref>{{cite book |title=The Century Dictionary and Cyclopedia, Vol. 6|first1=William Dwight |last1=Whitney |first2=Benjamin Eli |last2=Smith |year=1911 |publisher=The Century Company |location=New York |page=4123 |lccn=11031934 |url=https://books.google.com/books?id=dhTpAAAAMAAJ&pg=PA4123 }}</ref> For example, in diving birds, the operculum keeps water out of the nasal cavity;<ref name="Gill117"/> when the birds dive, the impact force of the water closes the operculum.<ref>{{cite magazine |title=Organisms as Functional Machines: A Connectivity Explanation |first=Walter J. |last=Bock |magazine=American Zoologist |year=1989 |jstor=3883510 |volume=29 |issue= 3 |pages=1119–1132 |doi=10.1093/icb/29.3.1119|doi-access=free }}</ref>}}

{{Term|overbrooding|content=overbrooding {{anchor|over-brooding|over brooding|overbrood|over-brood|over brood|overbroods|over-broods|over broods|overbrooded}} }}
{{defn|The not uncommon phenomenon of birds continuing to {{gli|brood}} eggs that are not viable and will not hatch, sometimes for lengthy periods of time beyond the normal incubation period.<ref name="Weaver83">{{Harvnb|Weaver|1981|p=83}}</ref>}}

{{Glossary end}}

==P==
[[File:Bird.parts.jpg|thumb|upright=1.25|{{gli|Topography}} of a typical passerine]]
{{Glossary}}
{{Term|passerine|content=passerine {{anchor|passerines|perching bird|perching birds}} }}
{{defn|''Also, '''perching bird'''.'' Any bird of the [[Biology:Order|order]] Passeriformes, which includes more than half of all bird species. A notable feature of passerines compared to other orders of Aves is the arrangement of their toes—three pointing forward and one back—which facilitates perching. Sometimes known as perching birds or, less accurately, as [[Biology:Songbird|songbird]]s, the passerines form one of the most diverse terrestrial [[Biology:Vertebrate|vertebrate]] orders, with over 5,000 identified [[Biology:Species|species]].<ref name="Ernst1946">{{cite magazine|last1=Mayr|first1=Ernst |url=http://sora.unm.edu/sites/default/files/journals/auk/v063n01/p0064-p0069.pdf|title=The Number of Species of Birds|magazine=The Auk|volume=63|issue= 1 |pages=64–69 |year=1946|doi=10.2307/4079907|jstor=4079907 }}</ref> The order has roughly twice as many species as [[Biology:Rodent|Rodent]]ia, the largest order of [[Biology:Mammal|mammal]]s. There are more than 110 families of passerine birds, the second-most of any tetrapods (after [[Biology:Squamata|Squamata]], the scaled reptiles).}}

{{Term|pectinate claw|content=pectinate claw {{anchor|pectinate claws|feather comb}} }}
{{defn|''Also, '''feather comb'''.''{{sfn|Lovette|Fitzpatrick|2016|p=181}} A claw on the middle toe of some birds, such as nightjars, herons, and barn owls,<ref name="Kennedy2014">{{cite book|last=Kennedy|first=Adam Scott|title=Birds of the Serengeti and Ngorongoro Conservation Area|url=https://books.google.com/books?id=gmmYDwAAQBAJ&pg=PA198|year=2014|publisher=Princeton University Press|isbn=978-0-691-15910-2|page=198}}</ref> with a serrated edge. The degree of [[Engineering:Serration|serration]] varies from fine to coarse, depending on the species. It is used in {{gli|preening}}, functioning similar to a comb. Some birds may use it to straighten the {{gli|rictal bristles}}.<ref>{{Harvnb|Elphick|2016|p=77}}</ref> It may also play an important role in parasite removal. For example, a study of barn owls found a significant correlation between the number of serrated teeth on an individual's pectinate claw, and the prevalance of its lice infestation.<ref name="BarnOwlLice">{{cite magazine|last1=Bush|first1=Sarah E.|last2=Villa|first2=Scott M.|last3=Boves|first3=Than J.|last4=Brewer|first4=Dallas|last5=Belthoff|first5=James R.|title=Influence of bill and foot morphology on the ectoparasites of barn owls| magazine=Journal of Parasitology|volume=98|issue=2|date=April 1, 2012|pages=256–261|url=https://doi.org/10.1645/GE-2888.1|doi=10.1645/GE-2888.1|pmid=22010835}}</ref>}}

{{Term|pectoral tuft|content=pectoral tuft {{anchor|pectoral tufts|pectoral-tuft|pectoral-tufts}} }}
{{defn|Elongated {{gli|feathers}}, often brightly coloured, which arise from the sides of the {{gli|chest}} of some species of birds, including many [[Biology:Sunbird|sunbird]]s, [[Biology:Spiderhunter|spiderhunter]]s and [[Biology:Flowerpecker|flowerpecker]]s.{{sfn|Cheke|Mann|Allen|2001|p=15}} They are typically hidden when the wing is folded on a perched bird, but prominent during courtship and territorial [[Biology:Display (zoology)|displays]].{{sfn|Cheke|Mann|Allen|2001|p=23}} In sunbirds and spiderhunters, these tufts may be yellow, red or orange; in flowerpeckers, they are usually white.{{sfn|Cheke|Mann|Allen|2001|p=15}} The size of the tufts in some species can be an indicator of a male's [[Biology:Fitness|fitness]] and status; males with larger tufts defend larger territories and have higher reproductive success.<ref>{{cite journal |first1=Matthew R. |last1=Evans |first2=B.J. |last2=Hatchwell |name-list-style=amp |title=An experimental study of male adornment in the scarlet-tufted malachite sunbird: I. The role of pectoral tufts in territorial defence |journal=Behavioral Ecology and Sociobiology |date=1992 |volume=29 |issue=6 |pages=413–419 |jstor=4600642 |url=https://www.researchgate.net/publication/227254273}}</ref>}}

{{Term|pennaceous feather|content=pennaceous feather {{anchor|pennaceous feathers|contour feather|contour feathers|pennaceous|contour}} }}
{{defn|''Also, '''contour feather'''.'' A type of {{gli|feather}} present in most modern birds and in some other species of maniraptoriform dinosaurs.<ref>{{Cite web|title=GEOL 204 The Fossil Record: Feathered Dragons: The Origins of Birds and of Avian Flight|url=http://www.geol.umd.edu/~tholtz/G204/lectures/204birds.html|publisher=Department of Geology at the University of Maryland|archive-url=https://web.archive.org/web/20170317235550/http://www.geol.umd.edu/~tholtz/G204/lectures/204birds.html|archive-date=March 17, 2017|access-date=January 29, 2017|url-status=dead}}</ref> Pennaceous feathers have a stalk called a {{gli|quill}}, with the basal part called a {{gli|calamus}}, that is embedded in the skin exclusively at {{gli|pterylae}} (feather tracts).<ref name="Chandler250">{{Harvnb|Chandler|1916|p=250}}</ref> The calamus is hollow and has pith formed from the dry remains of the feather pulp. The calamus stretches between two openings—at its base is the {{gli|inferior umbilicus}} and at its distal end is the {{gli|superior umbilicus}}; the {{gli|rachis}} of the main stem, hosting the {{gli|vanes}}, continues above it.<ref name="Ritchison">{{Cite web|last=Ritchison|first=Gary|title=Ornithology (Bio 554/754): Feather Evolution|url=http://people.eku.edu/ritchisong/feather_evolution.htm|publisher=Department of Biological Sciences, Eastern Kentucky University|access-date=January 16, 2017|archive-url=https://web.archive.org/web/20170225102837/http://people.eku.edu/ritchisong/feather_evolution.htm|archive-date=February 25, 2017|url-status=dead}}</ref> The rachides of contour feathers have an umbilical groove on their underside, with the vanes or ''vexilla'', spreading to either side. The vanes comprise many flattened {{gli|barbs}}, that are connected to one another by {{gli|hooklets}} that are anchored into flanges on {{gli|proximal barbules}} on neighboring barbs. Some specialized feathers are considered "modified" contour feathers, such as {{gli|ear coverts}} and bird eyelashes called {{gli|rictal bristles}}.<ref name="Chandler250"/> ''Contrast: {{gli|down feathers|plumulaceous (down) feathers}} and {{gli|filoplumes}}''.}}

{{Term|philopatry|content=philopatry {{anchor|philopatric}} }}
{{defn|The habit of a bird returning to the area it first bred.<ref name="Elphick136">{{harvnb|Elphick|2016|p=136}}</ref>}}

{{Term|pigeon milk}}
{{defn|The term for {{gli|crop milk}} when found among all [[Biology:Columbidae|pigeons and doves]].<ref name="Prolactin"/>}}

{{Term|pileum|content=pileum {{anchor|pileum of the head}} }}
{{defn|As defined in the treatise ''Manual of Ornithology: Avian Structure and Function'', the "''entire'' top of the head, including the {{gli|forehead}}, {{gli|crown}} and occipital regions."<ref name="Proctor64">{{Harvnb|Proctor|Lynch|1998|p=64}}</ref>}}

[[Image:Wellensittich01.jpg|thumb|upright=0.8|A budgerigar with {{gli|pin feathers}} showing on its breast.]]
{{Term|pin feather|content=pin feather {{anchor|pin feathers|blood feather|blood feathers}} }}
{{defn|''Also, '''blood feather'''.'' A developing {{gli|feather}} encased in a {{gli|feather sheath}} that, unlike a fully developed feather, has a blood supply flowing through it. As such, damage to pin feathers can cause significant bleeding. Pin feathers may be the first feather growth during a bird's infancy, or those growing during {{gli|moulting}} at any stage of a bird's life. As pin feather growth progresses, the blood supply is concentrated only in the base of the {{gli|calamus}}. Pin feathers begin to develop after the feather bud [[Philosophy:Invagination|invaginates]] a cylinder of [[Biology:Epidermis|epidermal tissue]] around the base of the dermal papilla, forming the feather follicle. At the base of the feather follicle, epithelial cells proliferate to grow the epidermal collar or cylinder. As the epidermal cylinder extends through [[Biology:Dermis|dermis]], it differentiates into a protective peripheral sheath, longitudinal barb ridges and growth plates. Over time these barb ridges grow in a [[Helix|helical]] manner, branching to create {{gli|barbs}} and {{gli|barbules}}, and fusing to form the central feather shaft. Moreover, the barb plate further differentiates into {{gli|hooklets}} and {{gli|cilia}}, while the marginal and axial plate die to form the intervening space within the feather structure.<ref name="Proctor86">{{Harvnb|Proctor|Lynch|1998|p=86}}</ref><ref name="Athan2008">{{cite book|last=Athan|first=Mattie Sue |title=Guide to the Quaker Parrot|url=https://books.google.com/books?id=wB6tG1E6O-QC&pg=PA57|year=2008|publisher=Barron's Educational Series|isbn=978-0-7641-3668-9|page=57}}</ref><ref name="Pettingill141-42">{{Harvnb|Pettingill|1985|pp=41–42}}</ref>}}

{{Term|pinioning|content=pinioning {{anchor|pinion joint|pinion joints}} }}
{{defn|''Also defined: '''pinion joint'''.'' The act of surgically removing one {{gli|pinion}} [[Biology:Joint|joint]]—the joint of a bird's wing farthest from the body—thereby stopping the growth of the {{gli|primary feathers}}, to prevent flight. The animal welfare impact of pinioning is subject to increasing debate. For example, it is known that the operation, which is often performed without pain relief, is just as painful in young birds as in mature birds, if not more so.<ref name=Hawkins /> Evidence also suggests that pinioning may cause a [[Unsolved:Phantom limb|phantom limb]] syndrome similar to what is observed in human amputees.<ref name="Hawkins">{{cite book|author1=Ian J. h. Duncan|author2=Penny Hawkins|title=The Welfare of Domestic Fowl and Other Captive Birds|url=https://books.google.com/books?id=mhnYLcXA6MYC&pg=PA84|year=2010|publisher=Springer|isbn=978-90-481-3649-0|pages=84–85}}</ref>}}

{{Term|pinions|content=pinions {{anchor|pinion}} }}
{{defn|The outermost {{gli|primaries}}—those connected to the phalanges.<ref>{{cite book|last=Hudson|first=W.H. |title=Harmsworth Natural History: A Complete Survey of the Animal Kingdom|url=https://books.google.com/books?id=zvxGAQAAMAAJ|year=1910|publisher=Carmelite House|location=London|page=926}}</ref>}}

[[File:Guiraca caeruleaAAP086CB.jpg|thumb|upright=1.25|The differences in plumage of [[Biology:Blue grosbeak|blue grosbeak]], from top to bottom, between a breeding male ({{gli|alternate plumage}}), a non-breeding male ({{gli|basic plumage}}), a female and a related indigo bunting]]
{{Term|plumage|content=plumage {{anchor|plumages}} }}
{{Main|Biology:Plumage}}
{{defn|Plumage ({{Lang-la|plūma}} 'feather') refers both to the layer of {{gli|feathers}} that cover a bird and the pattern, colour and arrangement of those feathers.<ref>{{Cite OED|Plumage}}</ref> The pattern and colours of plumage differ between species and subspecies, often vary with age and may vary sharply between males and females of the same species that exhibit {{gli|sexual dimorphism}}. Within species there can be different {{gli|colour morphs}}. Despite the great variance, as broad observations: 1) among many bird species adult males are more brightly coloured than are females, especially when in {{gli|alternate plumage|alternate or nuptial plumage}}, as opposed to {{gli|basic plumage|basic or winter plumage}}; 2) when male birds undergo the {{gli|prebasic moult}} and attain their non-breeding plumage, they much more closely resemble females; and 3) the plumage of juvenile birds (of both sexes) tends to be relatively dull and inconspicuous and typically resembles that of adult females.<ref name="Pettingill194">{{Harvnb|Pettingill|1985|p=194}}</ref>}}

{{Term|plumology|content=plumology {{anchor|plumage science}} }}
{{defn|''Also, '''plumage science'''.'' The name for the science that is associated with the study of {{gli|feathers}}.<ref name=GalaPlum>{{cite web|last1=Rosenberg|first1=Daniel K.|last2=Geist|first2=Dennis|last3=Harpp|first3=Karen|title=Galapagos plumology|url=http://www.darwinfoundation.org/datazone/galapagos-research/article/galapagos-plumology/|website=darwinfoundation.org|publisher=Charles Darwin Collections Database by the Charles Darwin Foundation|archive-url=https://web.archive.org/web/20160317093057/http://www.darwinfoundation.org/datazone/media/pdf/59/NG_59_1998_Harpp%26Geist_Galapagos_plumology.pdf|archive-date=March 17, 2016|access-date=January 29, 2017|issn=1390-2830|url-status=dead}}</ref><ref name=LangsFWPlumology>{{cite book|last1=Eichhorn|first1=hrsg. von Manfred|title=Langenscheidt Fachwörterbuch Biologie Englisch: englisch – deutsch, deutsch – englisch|date=2005|publisher=Langenscheidt|location=Berlin [u.a.]|isbn=978-3-86117-228-4|page=537|edition=1. Aufl.|url=https://books.google.com/books?id=KRJfNmHhIpUC&pg=PA537}}</ref>}}

{{Term|podotheca|content=podotheca {{anchor|foot sheath|scutellate|boot|booted|reticulate|boots}} }}
{{defn|''Also, '''foot sheath'''. Also defined: '''boot'''; '''reticulate'''; '''scutellate'''; '''booted'''.'' The skin that covers the bare feet and legs. It usually consists of many small scales, called {{gli|scutes}}. This type of podotheca is described as being scutellate. When there are no scutes, and the podotheca is a smooth sheath, it is called a boot, and those with podotheca like this are called booted. The podotheca may also be reticulated with small and irregularly raised plates. This arrangement is considered to be reticulate.<ref>{{Harvnb|Elphick|2016|p=33}}</ref>}}

{{Term|powder down|content=powder down {{anchor|powder-down|powder-down feather|powder-down feathers|powder down feather|powder down feathers|pulviplumes|pulviplume|feather dust}} }}
{{defn|''Also, '''pulviplumes'''; '''feather dust'''.'' A special type of {{gli|down}} that occurs in a few groups of apparently unrelated birds.  In some species, the tips of the {{gli|barbules}} on powder down feathers disintegrate, forming fine particles of [[Biology:Keratin|keratin]], which appear as a powder, or ''feather dust'', among the feathers. These feathers grow continuously and are not moulted.<ref>{{cite book |title=Home Study Course in Bird Biology, second edition |publisher=Cornell Laboratory of Ornithology |year=2003 |editor1-last=Podulka |editor1-first=Sandy |editor2-last=Rohrbaugh |editor2-first=Ronald W. |editor3-last=Bonney |editor3-first=Rick |page=55 (Glossary)}}</ref> In other species, the powder grains come from cells that surround the barbules of growing feathers.<ref name=Campbell208>{{harvnb|Campbell|Lack|1985|p=208}}</ref>  These specialized feathers are typically scattered among ordinary down feathers, though in some species, they occur in clusters.<ref name="HBW39"/> All [[Biology:Parrot|parrot]]s have powder down, with some species (including the mealy parrot) producing copious amounts.<ref>{{cite book |title=Parrots: A Guide to the Parrots of the World |first1=Tony |last1=Juniper |first2=Mike |last2=Parr |year=2003 |publisher=Christopher Helm |location=London |isbn=978-0-7136-6933-6 |page=17}}</ref> It is also found in [[Biology:Tinamou|tinamou]]s and [[Biology:Heron|heron]]s.<ref name="HBW39"/> The dust produced from powder down feathers is a known [[Biology:Allergen|allergen]] in humans.<ref>{{cite book |title=Allergic to Pets?: The Breakthrough Guide to Living with the Animals You Love |first=Shirlee |last=Kalstone |publisher=Bantam Dell |location=New York, NY |year=2006 |pages=[https://archive.org/details/isbn_9780553383676/page/34 34–35] |isbn=978-0-553-38367-6 |url=https://archive.org/details/isbn_9780553383676/page/34 }}</ref> ''Compare: {{gli|body down}} & {{gli|natal down}}''.}}

{{Term|postjuvenal moult}}
{{defn|''See {{gli|prebasic moult}}.''}}

{{Term|postnuptial moult}}
{{defn|''See {{gli|prebasic moult}}.''}}

{{Term|prealternate moult|content=prealternate moult {{anchor|prealternate moults|pre-alternate moult|pre-alternate moults|prenuptial moult|pre-nuptial moult|prenuptial moults|pre-nuptial moults}} }}
{{defn|''Also, '''prenuptial moult''' (sp. variation: in the U.S., sometimes molt).'' The {{gli|moult}} before the breeding season that most birds undergo, during which parts of the {{gli|basic plumage}} are shed and {{gli|nuptial plumage}} is grown. "Prealternate moult" is used in {{gli|Humphrey–Parkes terminology}}, and "prenuptial moult" is the traditional term. In either system of nomenclature, in juveniles this type of moult is numbered, 1st, 2nd, 3rd (etc.), until the {{gli|definitive plumage}} is attained, after which the numbering is dropped.<ref name="Lovette126">{{Harvnb|Lovette|Fitzpatrick|2016|p=126}}</ref> Unlike the {{gli|prebasic moult}}, in the prealternate moult the major {{gli|flight feathers}} and {{gli|primary coverts}} are not replaced in most species, and the feathers involved typically are "only head and body feathers, {{gli|wing coverts}} and sometimes {{gli|tertials}} and {{gli|rectrices}}".<ref name="HowellLewington2014">{{cite book|last1=Howell|first1=Steve N. G.|last2=Lewington|first2=Ian|last3=Russell|first3=Will|title=Rare Birds of North America|url=https://books.google.com/books?id=-YqGAAAAQBAJ&pg=PA34|date=February 16, 2014|publisher=Princeton University Press|isbn=978-1-4008-4807-2|page=34}}</ref>}}

{{Term|prebasic moult|content=prebasic moult {{anchor|prebasic moults|pre-basic moult|pre-basic moults|postnuptial moult|post-nuptial moult|postnuptial moults|post-nuptial moults|postjuvenal moult|post-juvenal moult|postjuvenal moults|post-juvenal moults|prebasic molt|prebasic molts|pre-basic molt|pre-basic molts|postnuptial molt|post-nuptial molt|postnuptial molts|post-nuptial molts|postjuvenal molt|post-juvenal molt|postjuvenal molts|post-juvenal molts}} }}
{{defn|''Also, '''postnuptial moult''' (sp. variation: in the U.S., sometimes molt).'' ''Also defined: '''postjuvenal moult'''.'' The {{gli|moult}} after the breeding season that most birds undergo, during which {{gli|nuptial plumage}} is shed and {{gli|basic plumage|basic or winter plumage}} is grown. In {{gli|Humphrey–Parkes terminology}}, prebasic moults in juveniles, prior to attaining {{gli|definitive plumage}}, are numbered the 1st, 2nd, 3rd (etc.) prebasic moult. In traditional terminology, the first is called the postjuvenal moult, and thereafter the 1st, 2nd, 3rd (etc.) postnuptial moult. In both nomenclature systems, after definitive plumage is reached, the numbering is dropped.<ref name="Lovette126"/>}}

{{Term|precocial|content=precocial {{anchor|semi-precocial|semiprecocial|semi precocial|altricial-precocial spectrum}} }}
{{defn|''Also defined: '''semi-precocial'''; '''altricial-precocial spectrum'''.'' Young that, at hatching, have their eyes open; are covered in {{gli|down feathers}} ({{gli|ptilopaedic}}); are [[Biology:Homeothermy|homeothermic]];<ref name="SummersCrespi2013"/> and are able to leave the nest soon after hatching and join their parents in {{gli|foraging}} activities ({{gli|nidifugous}}). The contrasting state is {{gli|altricial}} young, which are born "helpless"—more or less naked, blind, ectothermic and unable to leave the nest.<ref name="Johnston2013">{{cite book|last=Johnston|first=Richard|title=Current Ornithology|url=https://books.google.com/books?id=riYBCAAAQBAJ&pg=PA34|year=2013|publisher=Springer Science & Business Media|isbn=978-1-4615-6781-3|page=34}}</ref> The young of many bird species do not precisely fit into either the precocial or altricial category, having some aspects of each and thus fall somewhere on an ''altricial-precocial spectrum''.<ref name="Urfi2011"/> A defined intermediate state is termed ''semi-precocial'', typified by young born covered in down and with open eyes; that are usually able to walk shortly after hatching; but which remain mostly confined to the nest, relying on their parents for food ({{gli|nidicolous}}).<ref name="Pettingill371"/><ref name="Khanna2005">{{cite book|last=Khanna|first=D.R.|title=Biology of Birds|url=https://books.google.com/books?id=fDblIChi7KwC&pg=PA109|year=2005|publisher=Discovery Publishing House|isbn=978-81-7141-933-3|page=109}}</ref>}}

[[File:Passer domesticus bathing in water, Anas platyrhynchos in background.ogv|thumb|A [[Biology:House sparrow|house sparrow]] cleans itself in moving water while a mallard {{gli|preens}} in the background.]]
{{Term|preening|content=preening {{anchor|groom|preen|preens}} }}
{{defn|''Also, '''grooming'''.'' {{gli|Feathers}} require maintenance and birds preen or groom them daily, spending an average of around 9% of their daily time on this activity.<ref>{{cite magazine|last=Walther|first=Bruno A.|year=2005|title=Elaborate ornaments are costly to maintain: evidence for high maintenance handicaps|magazine=Behavioral Ecology|volume=16|issue= 1|pages=89–95|doi=10.1093/beheco/arh135|doi-access=free}}</ref> The {{gli|bill}} is used to brush away foreign particles and to apply [[Physics:Wax|wax]]y secretions from the [[Biology:Uropygial gland|uropygial gland]]; these secretions protect the feathers' flexibility and act as an [[Biology:Antimicrobial|antimicrobial agent]], inhibiting the growth of feather-degrading [[Biology:Bacteria|bacteria]].<ref>{{cite magazine|last1=Shawkey|first1=Matthew D.|year=2003|title=Chemical warfare? Effects of uropygial oil on feather-degrading bacteria |magazine=Journal of Avian Biology|volume=34|issue= 4|pages=345–49|doi=10.1111/j.0908-8857.2003.03193.x|last2=Pillai |first2=Shreekumar R.|last3=Hill|first3=Geoffrey E.}}</ref> This may be supplemented with the secretions of [[Chemistry:Formic acid|formic acid]] from ants, which birds receive through a behaviour known as {{gli|anting}}, to remove feather parasites.<ref>{{cite magazine|last=Ehrlich|first=Paul R.|year=1986|title=The Adaptive Significance of Anting|magazine=The Auk|volume=103|issue= 4|page=835|url=http://sora.unm.edu/sites/default/files/journals/auk/v103n04/p0835-p0835.pdf|archive-url=https://web.archive.org/web/20160305202116/http://sora.unm.edu/sites/default/files/journals/auk/v103n04/p0835-p0835.pdf|archive-date=March 5, 2016|url-status=dead|df=dmy}}</ref>}}

{{Term|prenuptial moult}}
{{defn|''See {{gli|prealternate moult}}.''}}

{{Term|primaries|content=primaries {{anchor|primary feather|primary feathers|primary|primary remiges|primary remex}} }}
{{defn|''Also, '''primary feathers'''; '''primary remiges'''.'' A type of {{gli|remex}} flight feather, they are connected to the manus (the bird's "hand", composed of carpometacarpus and phalanges); these are the longest and narrowest of the remiges (particularly those attached to the phalanges), and they can be individually rotated. These feathers are especially important for flapping flight, as they are the principal source of [[Thrust|thrust]], moving the bird forward through the air. Most thrust is generated on the downstroke of flapping flight. However, on the upstroke (when the bird often draws its wing in close to its body), the primaries are separated and rotated, reducing air resistance while still helping to provide some thrust.<ref>{{Harvnb|Ehrlich|Dobkin|Wheye|Pimm|1994|p=219}}</ref> The flexibility of the remiges on the wingtips of large soaring birds also allows for the spreading of those feathers, which helps to reduce the creation of wingtip [[Vortex|vortices]], thereby reducing drag.<ref>{{Harvnb|Ehrlich|Dobkin|Wheye|Pimm|1994|p=79}}</ref> In most flighted birds, some of the distal {{gli|barbules}} on the inner {{gli|vane}} of these feathers, called {{gli|friction barbules}}, are specialized, with large lobular barbicels that are thought to help grip and prevent slippage of overlying feathers.<ref>{{cite magazine|last1=Muller|first1=Werner|last2=Patone|first2=Giannino |year=1998|title=Air transmissivity of feathers|magazine=Journal of Experimental Biology|volume=201|pages=2591–2599|url=http://jeb.biologists.org/cgi/reprint/201/18/2591.pdf|pmid=9716511|issue= 18}}</ref> Species vary in the number of primaries they possess. The number in non-passerines generally varies between 9 and 11,<ref name="Jenni7">{{cite book|last1=Jenni|first1=Lukas|last2=Winkler|first2= Raffael|title=Moult and Ageing of European Passerines|year=1994|publisher=Academic Press|location=London |isbn=978-0-12-384150-6|page=7}}</ref> but [[Biology:Grebe|grebe]]s, [[Biology:Stork|stork]]s and [[Biology:Flamingo|flamingo]]s have 12 and [[Biology:Ostrich|ostrich]]es have 16.<ref name="HBW37">{{Harvnb|del Hoyo|Elliott|Sargatal|1992|p=37}}</ref> While most modern [[Biology:Passerine|passerine]]s have ten primaries,<ref name="Jenni7"/> some have only nine. Those with nine are missing the most distal primary, sometimes called the {{gli|remicle}}, which is typically very small and sometimes rudimentary in passerines.<ref name="HBW37"/>}}

{{Term|primary projection|content=primary projection {{anchor|primary projections|primary extension|primary extensions}} }}
{{defn|''Also, '''primary extension'''.'' The distance that a bird's longest primaries extend beyond its longest secondaries (or {{gli|tertials}}) when its wings are folded.<ref name="Kaufman">{{cite book |last=Kaufman |first=Kenn |title=Advanced Birding |publisher=Houghton Mifflin |location=Boston |year=1990 |isbn=978-0-395-53376-5 |pages=[https://archive.org/details/fieldguidetoadva00kauf/page/186 186] |url=https://archive.org/details/fieldguidetoadva00kauf/page/186 }}</ref> As with {{gli|wing formulae}}, this measurement is useful for distinguishing between similarly plumaged birds; however, unlike wing formulae, it is not necessary to have the bird in-hand to make the measurement. Rather, this is a useful ''relative'' measurement—some species have long primary extensions, while others have shorter ones. Among the ''[[Biology:Empidonax|Empidonax]]'' [[Biology:Tyrant flycatcher|flycatchers]] of the Americas, for example, the [[Biology:American dusky flycatcher|dusky flycatcher]] has a much shorter primary extension than does the very similarly plumaged [[Biology:Hammond's flycatcher|Hammond's flycatcher]].<ref name="Kaufman"/> Europe's common skylark has a long primary projection, while that of the near-lookalike [[Biology:Oriental skylark|Oriental skylark]] is very short.<ref>{{Cite book |last1=Svensson |first1=Lars |last2=Grant|first2=Peter J. |title=Collins Bird Guide: The Most Complete Field Guide to the Birds of Britain and Europe |year=1999 |publisher=HarperCollins |location=London |isbn=978-0-00-219728-1 |pages=231}}</ref> As a general rule, species which are long distance migrants will have longer primary projection than similar species which do not migrate or migrate shorter distances.<ref>{{cite book|last=Christie|first=Thomas Alerstam; translated by David A.|title=Bird migration|date=1993|publisher={{wipe|Cambridge University Press}}|location=Cambridge [England]|isbn=978-0-521-44822-2|pages=253}}</ref>}}

{{Term|proventriculus|content=proventriculus {{anchor|proventriculi}} }}
{{Main|Biology:Proventriculus}}
{{defn|The first part of the stomach of a bird. The inside is lined with gastric glands, which secrete gastric juices containing enzymes and hydrochloric acid. In some birds, such as petrels, the proventriculus is expandable. This allows these birds to either digest their food later or carry it back to their young. The proventriculus leads into the {{gli|gizzard}}.<ref name="Elphick49">{{Harvnb|Elphick|2016|p=49}}</ref>}}

{{Term|psilopaedic}}
{{defn|Young that are born naked or with only a small amount of {{gli|down}} feather coverage, as opposed to birds that are {{gli|ptilopaedic}}.<ref name="Pettingill371"/>}}

{{Term|pterylae|content=pterylae {{anchor|pterylya|feather tracts|feather tract|tracts|tract}} }}
{{defn|''Singular: '''pteryla'''.'' The feather tracts of a bird's skin from which the {{gli|contour feathers}} grow, often in sharply defined and dense clusters—as opposed to the {{gli|apterylae}}.<ref name="Proctor98"/> ''See related: {{gli|pterylosis}}.''}}

[[File:PasserinePterylosis (cropped).jpg|thumb|{{gli|Pterylosis}} (feather arrangement) of a typical {{gli|passerine}}]]
{{Term|pterylosis|content=pterylosis {{anchor|pterylya}} }}
{{defn|''Also, '''pterylography'''.'' The arrangement of feather tracts, as seen in a bird's {{gli|pterylae}} and {{gli|apterylae}}, which varies across bird families and has been used in the past as a means for determining the evolutionary relationships among them.<ref>{{cite magazine|magazine=Journal of Ornithology| title= Do nine-primaried passerines have nine or ten primary feathers? The evolution of a concept| volume=146| issue= 2| pages=121–126| year=2005|last1=Hall|first1=K.|last2=Susanna|first2=S. |doi=10.1007/s10336-004-0070-5| s2cid= 36055848}}</ref><ref>{{cite magazine|last= Pycraft| first=W. P.|year=1895|title=On the pterylography of the hoatzin (''Opisthocomus cristatus'')| magazine= Ibis| volume=37| pages= 345–373|doi=10.1111/j.1474-919X.1895.tb06744.x|issue= 3}}</ref>}}

{{Term|ptilopaedic}}
{{defn|Young that are born covered with {{gli|down}} feathers, as opposed to birds that are {{gli|psilopaedic}}.<ref name="Pettingill371"/>}}

{{Term|pupil|content=pupil {{anchor|pupils}} }}
{{defn|The dark disk at the centre of a bird's eye through which light enters, surrounded by the coloured outer ring of the {{gli|iris}}.<ref>{{cite book|last1=Baird|first1=Spencer Fullerton|last2=Brewer|first2=Thomas Mayo|last3=Ridgway|first3=Robert|title=A History of North American Birds|url=https://books.google.com/books?id=PF8MAQAAIAAJ&pg=PA554|year=1874|publisher=Little, Brown|page=554}}</ref>}}

{{Term|pygostyle|content=pygostyle {{anchor|pygostylea|tailbone|tailkbones|tail bone|tail bones}} }}
{{defn|''Also, '''tail bone'''.'' A skeletal formation, [[Plowshare|plowshare]]-shaped in birds, in which the final few caudal [[Biology:Vertebra|vertebra]]e are fused into a single [[Biology:Ossification|ossification]], supporting the tail feathers and musculature. In modern [[Biology:Bird|bird]]s, the {{gli|rectrices}} attach to these. The pygostyle is the main component of the {{gli|uropygium}}.<ref name="Chatterjee2015">{{cite book|last=Chatterjee|first=Sankar|title=The Rise of Birds: 225 Million Years of Evolution|url=https://books.google.com/books?id=V-okBwAAQBAJ&pg=PA114|year=2015|publisher=JHU Press|isbn=978-1-4214-1614-4|pages=114–115}}</ref><ref name="Lovette177">{{Harvnb|Lovette|Fitzpatrick|2016|p=177}}</ref>}}

{{Glossary end}}

==Q==
{{Glossary}}
{{Term|quartering}}
{{defn|A hunting technique where a bird flies slowly just above the water or ground in open habitats.<ref name="Elphick2016-117">{{Harvnb|Elphick|2016|p=117}}</ref>}}

{{Term|quill|content=quill {{anchor|quills|main stem|scapus|primary quill}} }}
{{defn|''Also, '''primary quill'''; '''main stem'''; '''scapus'''.'' The main stem of a feather from which all structures branch, if any. The proximal portion is called the {{gli|calamus|calamus or shaft}}, and the distal portion is called the {{gli|rachis}}, with the demarcation point between them usually defined as the {{gli|superior umbilicus}}.<ref name="Chandler250"/><ref name="Pettingill29–32"/> However, some authorities define quill very differently, using it as a synonym for the calamus.<ref name="Gill80">{{Harvnb|Gill|1995|p=80}}</ref> The contradiction between sources on this issue is quite sharp. For example, in Asa Chandler's well known treatise, ''A study of the structure of feathers, with reference to their taxonomic significance'', "quill" is defined at page 250 as: "The main stem of a feather, including both shaft and calamus (Coues, 1884; Beebe, 1906, et al.). ''Synonyms:'' main stem (Nitzsche, 1867)".<ref name="Chandler250"/> By contrast, in Frank B. Gill's well known treatise, ''Ornithology'', he writes at page 80: "The hollow base of the shaft—the calamus, or quill—anchors the feather in a follicle below the surface of the skin".<ref name="Gill80"/> In ''this glossary'', the former definition will be used, treating quill as denoting the "main stem" of a feather.}}

{{Glossary end}}

==R==
{{Glossary}}
{{Term|rachis|content=rachis {{anchor|quill|quills|rachises|rachides|medulla|medullae|shaft|shafts|rhachis|rhachises|rhachides}} }}
{{defn|''Plural: '''rachises'''; '''rachides'''.  Also, '''shaft'''. Variable sp.: '''rhachis'''.<ref>{{cite magazine|last=Lillie|first=Frank R.|title=On the Development of Feathers|date=November 1941|page=247|magazine=Biological Reviews|volume=17|issue= 3|doi=10.1111/j.1469-185X.1942.tb00439.x|s2cid=84592534}}</ref> Also defined: '''medulla'''.'' The distal or upper section of the {{gli|quill}}, above the {{gli|calamus}}, stretching from the {{gli|superior umbilicus}} to the tip of the feather, upon which the {{gli|vanes}} and other structures are anchored. The rachis is flexible from side to side toward the blade projections, but far stiffer inward and outward from the bird's body. This arrangement aids in allowing the {{gli|flight feather}} to act as a "resilient airfoil".<ref name="Pettingill29–32">{{Harvnb|Pettingill|1985|pages=29–32}}</ref> The rachis is composed of two layers: a pithy, opaque material makes up the core layer called the ''medulla'', which is covered by a thin and translucent outer layer or ''cortex'' that features longitudinal internal ridges on the dorsal side and external ridges on the ventral side.<ref name="Pettingill32"/>}}

{{Term|rectrices|content=rectrices {{anchor|rectrice|rectrix}} }}
{{defn|''Singular: '''rectrix'''.'' From the Latin for 'helmsman', they are the long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the tail of a bird, which help it to brake and steer in flight. They lie in a single horizontal row on the rear margin of the anatomic tail. The vast majority of species having six pairs. They are absent in grebes and some [[Biology:Ratite|ratite]]s, and greatly reduced in size in penguins.<ref name="HBW37"/><ref>{{Harvnb|del Hoyo|Elliott|Sargatal|1992|pp=84–85, 91, 104}}</ref><ref>{{Harvnb|del Hoyo|Elliott|Sargatal|1992|p=141}}</ref> Many [[Biology:Grouse|grouse]] species have more than 12 rectrices. Some species (including ruffed grouse, [[Biology:Hazel grouse|hazel grouse]] and [[Biology:Common snipe|common snipe]]) have a number that varies among individuals.<ref>{{Cite book |last1=Madge |first1=Steve |last2=McGowan|first2=Phil|title=Pheasants, Partridges & Grouse |year=2002 |publisher=Christopher Helm |location=London |isbn=978-0-7136-3966-7 |pages=375}}</ref> [[Biology:Domestic pigeon|Domestic pigeon]]s have a highly variable number, due to centuries of selective breeding.<ref>{{Harvnb|del Hoyo|Elliott|Sargatal|1992|p=105}}</ref>}}

{{Term|remiges|content=remiges {{anchor|remige|remex|postpatagium}} }}
{{defn|''Singular: '''remex'''. Also defined: '''postpatagium'''.'' From the Latin for 'oarsman', they are the long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the [[Physics:Wing|wing]]s of a bird. They are located on the posterior side of the wing. [[Biology:Ligament|Ligament]]s attach the long ''calami'' firmly to the wing bones, and a thick, strong band of [[Biology:Tendon|tendinous]] tissue known as the ''postpatagium'' helps to hold and support the remiges in place.<ref>{{cite book |title=Home Study Course in Bird Biology, Second Edition |editor-last1=Podulka|editor-first1=Sandy|editor-last2=Rohrbaugh|editor-first2=Ronald W.|editor-last3=Bonney|editor-first3=Rick|year=2003 |publisher=Cornell Lab of Ornithology|location=Ithaca, New York |page=1.11}}</ref> Corresponding remiges on individual birds are [[Symmetry|symmetrical]] between the two wings, matching to a large extent in size and shape (except in the case of [[Biology:Mutation|mutation]] or damage), though not necessarily in pattern.<ref name="Trail8">{{Harvnb|Trail|2001|p=8}}</ref><ref>{{cite magazine|last1=Moller|first1=Anders Pape|last2=Hoglund|first2=Jacob |year=1991|title=Patterns of Fluctuating Asymmetry in Avian Feather Ornaments: Implications for Models of Sexual Selection|magazine=Proceedings: Biological Sciences|volume=245|issue= 1312|pages=1–5|doi=10.1098/rspb.1991.0080|bibcode=1991RSPSB.245....1P|s2cid=84991514}}</ref> They are given different names depending on their position along the wing.}}

[[File:Sylviaatricapillamap2.png|thumb|upright=0.8|<div style="text-align:left;">{{Legend2|#FFFF00| Breeding summer visitor|border=1px solid#aaa}}<br /> {{Legend2|#00FF00| Resident year-round|border=1px solid#aaa}}<br />{{Legend2|#0080FF| Winter visitor|border=1px solid #aaa}}</div><br />Range map for Eurasian blackcaps—corresponding to the example use of {{nowrap|"{{gli|resident}}"}} in its definition at the left]]
{{Term|remicle|content=remicle {{anchor|little remex}} }}
{{defn|''Also, '''little remex'''.'' The most distal {{gli|primary feather}}. The remicle is very small and usually non-functional—interpreted by Christian Ludwig Nitzsch as "an aborted first primary". It was named by Richard S. Wray in 1887, who similarly thought of it as "representing an originally functional primary".<ref>{{cite magazine|magazine=The Condor|volume=65|issue= 6|date=November–December 1963|last1=Stresemann|first1=Erwin|url=https://sora.unm.edu/sites/default/files/journals/condor/v065n06/p0449-p0459.pdf|title=Variations in the Number of Primaries|pages=449–459|doi=10.2307/1365506|jstor=1365506}}</ref>}}

{{Term|resident|content=resident {{anchor|residents|permanent resident|permanent residents|sedentary}} }}
{{defn|''Also, '''permanent resident'''; '''sedentary'''.'' Non-[[Biology:Bird migration|migratory]]; a bird that stays year-round and breeds in one geographic area or habitat.<ref name="Lovette458">{{Harvnb|Lovette|Fitzpatrick|2016|p=458}}</ref> Both ''permanent resident'' and ''sedentary'' are common with the defined usage. Although ''resident'' is used in this sense, it is often used as well for birds that are "migratory in part of their breeding range and resident elsewhere",<ref name="Terrill&Able">{{cite magazine|last1=Terrill|first1=Scott B.|last2=Abel|first2=Kenneth P.|title=Bird Migration Terminology|magazine=The Auk|date=January 1988|volume=105|url=https://sora.unm.edu/sites/default/files/journals/auk/v105n01/p0205-p0206.pdf|page=206|doi=10.1093/auk/105.1.205}}</ref> e.g., "Eurasian blackcaps (''Sylvia atricapilla'') are summer visitors to Eastern and Northern Europe, resident in Western Europe and winter visitors to Africa."}}

[[File:BarbetRictalBristle.jpg|thumb|{{gli|Rictal bristles}} of a [[Biology:White-cheeked barbet|white-cheeked barbet]]]]
{{Term|rictal bristles|content=rictal bristles {{anchor|rictal bristle|bristle|bristles|bristle feather|bristle feathers|rictal bristle feather|rictal bristle feathers|eyelashes| eye lashes}} }}
{{defn|''Also, '''bristles'''; '''bristle feathers'''; '''eyelashes'''.'' Stiff, hair-like, tapering feathers with a large {{gli|rachis}} but few {{gli|barbs}} found around the eyes and the base of the {{gli|beak}} of some bird species.<ref name="Lederer">{{cite magazine |title=The Role of Avian Rictal Bristles |first=Roger J |last=Lederer |url=http://sora.unm.edu/sites/default/files/journals/wilson/v084n02/p0193-p0197.pdf |magazine=The Wilson Bulletin |volume=84 |pages=193–197 |issue= 2}}</ref> They are common among insectivorous birds, but are also found in some non-insectivorous species.<ref name="Conover">{{cite magazine |title=Rictal Bristle Function in Willow Flycatcher |first1=Michael R. |last1=Conover |first2=Don E. |last2=Miller |magazine=The Condor |volume=82 |issue= 4 |pages=469–471 |date=November 1980 |url=http://sora.unm.edu/sites/default/files/journals/condor/v082n04/p0469-p0471.pdf |doi=10.2307/1367580|jstor=1367580 }}</ref> They may serve a similar purpose to [[Medicine:Eyelash|eyelash]]es and vibrissae in [[Biology:Mammal|mammal]]s. Although there is as yet no clear evidence, it has been suggested that rictal bristles have sensory functions and may help insectivorous birds to capture prey.<ref name="Lederer"/><ref>{{cite magazine| url=http://sora.unm.edu/sites/default/files/journals/wilson/v084n02/p0193-p0197.pdf |title=The role of avian rictal bristles |last= Lederer| first=Roger J. |year=1972 |magazine=The Wilson Bulletin |volume=84|pages= 193–97}}</ref> There is some experimental evidence to suggest that bristles may prevent particles from striking the eyes if, for example, a prey item is missed or breaks apart upon contact.<ref name="Conover"/>}}

{{Term|rosette|content=rosette {{anchor|gape rosette|rosettes|gape rosettes}} }}
{{defn|''Also, '''gape rosette'''.'' A fleshy rosette found at the corners of the beaks of some birds, such as the [[Biology:Puffin|puffin]].<ref>{{cite magazine|url=http://www.seabirdgroup.org.uk/journals/seabird_27/seabird-27-21.pdf|title=Aging Atlantic Puffins ''Fratercula arctica'' in summer and winter|archive-url=https://web.archive.org/web/20160611084736/http://www.seabirdgroup.org.uk/journals/seabird_27/seabird-27-21.pdf|archive-date=June 11, 2016|url-status=dead|last1=Harris|first1=Mike P.|year=2014|magazine=Seabird|volume=27|pages= 22–40}}</ref> In the puffin, this is grown as part of its display plumage.<ref>{{cite web|url=http://www.welshwildlife.org/wp-content/uploads/2011/05/Puffin.pdf|title=Skomer Island Puffin Factsheet|date=May 2011|publisher=Wildlife Trust of South & West Wales|website=welshwildlife.org|access-date=2017-01-20|archive-date=2020-10-19|archive-url=https://web.archive.org/web/20201019210122/http://www.welshwildlife.org/wp-content/uploads/2011/05/Puffin.pdf|url-status=dead}}</ref>}}

{{Term|rhamphotheca}}
{{defn|The outer surface of the beak consisting of a thin horny sheath of [[Biology:Keratin|keratin]],<ref name="Proctor66"/><ref name="Gill148"/> which can be subdivided into the {{gli|rhinotheca}} of the {{gli|upper mandible}} and the {{gli|gnathotheca}} of the {{gli|lower mandible}}.<ref name="Campbell47"/> This covering arises from the Malpighian layer of the bird's [[Biology:Epidermis (zoology)|epidermis]],<ref name="Campbell47"/> growing from plates at the base of each mandible.<ref>{{cite book |title=Veterinary Nursing of Exotic Pets |first=Simon |last=Girling |year=2003 |publisher=Blackwell Publishing |location=Oxford, UK |isbn=978-1-4051-0747-1|page=4}}</ref> There is a [[Medicine:Vascular|vascular]] layer between the rhamphotheca and the deeper layers of the [[Biology:Dermis|dermis]], which is attached directly to the [[Biology:Periosteum|periosteum]] of the bones of the beak.<ref name="Samour296">{{cite book |title=Avian Medicine |editor-first=Jaime |editor-last=Samour |year=2000 |publisher=Mosby |location=London, UK |isbn=978-0-7234-2960-9|page=296}}</ref> The rhamphotheca grows continuously in most birds, and in some species, the colour varies seasonally.<ref>{{cite magazine| title=Indentation hardness of the bill keratin of the European Starling|last1=Bonse|first1=R.H.|last2=Witter|first2=Mark S.|magazine=The Condor| volume=95|issue= 3| pages=736–738| year=1993| url=http://sora.unm.edu/sites/default/files/journals/condor/v095n03/p0736-p0738.pdf| doi=10.2307/1369622|jstor=1369622}}</ref>}}

{{Term|rhinotheca}}
{{defn|The {{gli|rhamphotheca}} (thin horny sheath of [[Biology:Keratin|keratin]]) covering the {{gli|upper mandible}}.<ref name="Proctor66"/><ref name="Gill148"/><ref name="Campbell47"/>}}

{{Term|rump|content=rump {{anchor|rumps|uropygium|parson's nose|pope's nose|sultan's nose|lower back|uropygial region}} }}
{{defn|''Also, '''uropygium'''; '''uropygial region''';  '''parson's nose''', '''pope's nose'''; '''sultan's nose'''.'' {{gli|topography|Topographically}}, the region of a bird's {{gli|upperparts}} between the end of the back and the base of the tail.<ref name="Pettingill8"/> ''Anatomically'', the fleshy protuberance visible at the posterior end of a bird. Its swollen appearance results from it housing the {{gli|uropygial gland}}.<ref name="Damerow2012">{{cite book|last=Damerow|first=Gail|title=The Chicken Encyclopedia: An Illustrated Reference|url=https://books.google.com/books?id=YTkBu_R6jiYC&pg=PA278|year=2012|publisher=Storey Publishing, LLC|isbn=978-1-60342-561-2|page=278}}</ref> ''See related: {{gli|pygostyle}}.''}}

{{Glossary end}}

==S==
{{Glossary}}
[[File:Riesenseeadler Fang.JPG|thumb|{{gli|Scales}} on the {{gli|talons}} of a [[Biology:Steller's sea eagle|Steller's sea eagle]] (''Haliaeetus pelagicus'')]]
{{Term|scales|content=scales {{anchor|scale|cancella|cancellas|cancellae|scutella|scutellae|cutellas|scute|scutes|acrometatarsium|acrotarsium|Reticulae}} }}
{{defn|''Specialized types: '''cancella'''; '''scutella'''; '''scutes'''. Also defined: '''reticulae'''; '''acrometatarsium'''&thinsp;/&thinsp;'''acrotarsium'''.'' The [[Biology:Scale (anatomy)|scales]] of birds are composed of keratin like their beaks and claws, and are found mainly on the toes and metatarsus, though they may appear further up on the ankle. They do not overlap significantly, except in the cases of [[Biology:Kingfisher|kingfisher]]s and [[Biology:Woodpecker|woodpecker]]s. The scales and scutes of birds were originally thought to be [[Biology:Homology|homologous]] to those of reptiles and mammals;<ref name=Lucas>{{cite book |last=Lucas |first=Alfred M. |year=1972 |title=Avian Anatomy – integument |location=East Lansing, Michigan |publisher=USDA Avian Anatomy Project, Michigan State University |pages=67, 344, 394–601}}</ref> later research, however, suggests that scales in birds re-evolved after the evolution of feathers.<ref name=Sawyer>Sawyer, R.H., Knapp, L.W. 2003. Avian Skin Development and the Evolutionary Origin of Feathers. J.Exp.Zool. (Mol.Dev.Evol) 298B:57–72.</ref><ref name="Dhouailly">{{cite magazine|magazine=Journal of Anatomy|last=Dhouailly|first=D.|date=April 2009|title=A New Scenario for the Evolutionary Origin of Hair, Feather, and Avian Scales|volume=214|issue= 4|pages=587–606|doi=10.1111/j.1469-7580.2008.01041.x|pmid=19422430|pmc=2736124}}</ref> Bird embryos begin development with smooth skin. On the feet, the [[Biology:Stratum corneum|corneum]], or outermost layer of this skin may keratinize, thicken and form scales. Bird scales can be organized into:<br />i) ''cancella''—minute scales which are really just a thickening and hardening of the skin, crisscrossed with shallow grooves;<ref name="LucasStettenheim1972">{{cite book|last1= Lucas|first1=Alfred Martin|last2=Stettenheim|first2=Peter Rich|title=Avian Anatomy Integument|url=https://books.google.com/books?id=GoIWAAAAYAAJ|year=1972|publisher=U.S. Government Printing Office|page=597}}</ref><br />ii) ''scutella''—scales that are not quite as large as scutes, such as those found on the caudal, or hind part, of the chicken metatarsus;<ref name="LucasStettenheim1972"/> and <br />iii) ''[[Biology:Scute|scute]]s''—the largest scales, usually on the anterior surface of the metatarsus and dorsal surface of the toes. The rows of scutes on the anterior of the metatarsus is sometimes termed an "acrometatarsium" or "acrotarsium".<ref name="LucasStettenheim1972"/><br />''Reticulae'', by contrast, are small, keeled ''scale-like'' structures covering the bottoms of bird feet, but are not true scales. Evolutionary developmental studies on reticulae found that they are composed entirely of [[Biology:Alpha-keratin|alpha-keratin]] (whereas, true epidermal scales are composed of a mix of alpha and beta keratin).<ref name="Dhouailly"/> This, along with their unique structure, has led to the suggestion that reticulae are actually feather buds that were arrested early in development.<ref name="Stettenheim"/><ref name="Dhouailly"/><ref>{{cite magazine|last1=Zheng|first1 =X.|last2=Zhou|first2=Z.|last3=Wang|first3=X.|last4=Zhang|first4= F.|last5=Zhang|first5=X.|last6=Wang|first6=Y.|last7=Xu|first7=X.|year=2013|title=Hind wings in basal birds and the evolution of leg feathers|magazine=Science|volume=339|issue= 6125|pages=1309–1312|doi=10.1126/science.1228753|pmid=23493711|bibcode =2013Sci...339.1309Z|citeseerx =10.1.1.1031.5732|s2cid =206544531}}</ref> ''See also: {{gli|podotheca}}.''}}

{{Term|scapulars|content=scapulars {{anchor|scapular|scapula|humeral region}} }}
{{defn|''Also, '''humeral region'''.'' Feathers covering a bird's scapula "at the base of the dorsal wing".<ref name="Campbell52">{{Harvnb|Campbell|Lack|1985|p=52}}</ref>}}

{{Term|secondaries|content=secondaries {{anchor|secondary feather|secondary feathers|secondary remiges|secondary remex|quill knobs}} }}
{{defn|''Also, '''secondary feathers'''; '''secondary remiges'''.'' A type of {{gli|remex}} flight feather, they are connected to the [[Biology:Ulna|ulna]]. In some but not all bird species, the ligaments that bind secondaries to the bone connect to small, rounded projections that are called quill knobs. Secondary feathers remain close together in flight (they cannot be individually separated like the primaries can) and help to provide lift by creating the airfoil shape of the bird's wing. Secondaries tend to be shorter and broader than primaries, with blunter ends. They vary in number from six in [[Biology:Hummingbird|hummingbird]]s, to as many as 40 in some species of [[Biology:Albatross|albatross]]. In general, larger and longer-winged species have a larger number of secondaries.<ref name="Sibley17"/> Birds in more than 40 non-{{gli|passerine}} families are missing the fifth secondary feather on each wing; a state known as {{gli|diastataxis}}.<ref name="Campbell656"/>}}

{{Term|semiplume|content=semiplume {{anchor|semiplumes|semi-plume|semi-plumes|semi plume|semi plumes|semiplume feather|semiplume feathers|semi-plume feather|semi-plume feathers|semi plume feather|semi plume feathers}} }}
{{defn|''Also, '''semiplume feather'''.'' A type of feather that has features straddling the differences between true {{gli|down}} and {{gli|contour}} feathers, such as by lacking cross-attachment between their {{gli|barbs}} (i.e., without a {{gli|flange}}–{{gli|hooklet}} anchoring system), but having a central, full-length shaft as in contour feathers. They are usually found on the margins of the pennaceous {{gli|pterylae|feather tracts}} and, like down, provide insulative qualities and help fill out the plumage. {{gli|Crest feathers}} are a type of semiplume.<ref name="FarnerKing2013"/><ref name="ScottMcFarland2010">{{cite book|last1=Scott|first1=S. David|last2=McFarland|first2=Casey|title=Bird Feathers: A Guide to North American Species|url=https://books.google.com/books?id=LhdExsnFNKIC&pg=PA15|year=2010|publisher=Stackpole Books|isbn=978-0-8117-4217-7|page=15}}</ref><ref name="Pettingill39">{{Harvnb|Pettingill|1985|p=39}}</ref>}}

[[File:Male and female pheasant.jpg|thumb|{{gli|Sexually dimorphic}} female (left) and male (right) [[Biology:Common pheasant|common pheasant]], illustrating the dramatic difference in both colour and size between the species' sexes]]

{{Term|sexual dimorphism|content=sexual dimorphism {{anchor|sexually dimorphic|dimorphism|dimorphic}} }}
{{defn|The common phenomenon amongst birds in which males and females of the same species exhibit different characteristics beyond the differences in their sexual organs. It can manifest in size or plumage differences. Sexual size dimorphism varies among taxa with males typically being larger, though this is not always the case, i.e., in birds of prey, [[Biology:Hummingbird|hummingbird]]s and some species of flightless birds.<ref>{{cite book|last=Andersson|first=Malte B.|title= Sexual Selection|publisher= Princeton University Press|year= 1994|url= https://books.google.com/books?id=lNnHdvzBlTYC|isbn=978-0-691-00057-2|page=269}}</ref><ref>{{cite magazine|title=Becoming Different But Staying Alike: Patterns of Sexual Size and Shape Dimorphism in Bills of Hummingbirds|magazine=Evolutionary Biology|date=November 11, 2012|issn= 0071-3260|pages= 246–260|volume=40|issue= 2|doi=10.1007/s11692-012-9206-3|first1= Chelsea M.|last1= Berns|first2=Dean C.|last2 =Adams}}</ref> Plumage dimorphism, in the form of ornamentation or colouration, also varies, though males are typically the more ornamented or brightly coloured sex.<ref>{{cite magazine |last1=McGraw|first1=K. J.|last2=Hill|first2=G. E.|last3=Stradi|first3=R.|last4=Parker|first4=R. S.|year=2002|title=The effect of dietary carotenoid access on sexual dichromatism and plumage pigment composition in the American goldfinch |url=http://www.aces.edu/dept/hilllab/81.pdf|archive-url=https://web.archive.org/web/20050828183926/http://www.aces.edu/dept/hilllab/81.pdf|archive-date=August 28, 2005|magazine=Comparative Biochemistry and Physiology Part B-Biochemistry and Molecular Biology|volume=131|issue= 2|pages=261–269 |doi=10.1016/S1096-4959(01)00500-0|pmid=11818247}}</ref> Such differences have been attributed to the unequal reproductive contributions of the sexes.<ref>{{cite magazine|last1=Owens|first1=I. P. F.|last2=Hartley|first2=I. R.|year=1998|title=Sexual dimorphism in birds: why are there so many different forms of dimorphism? |magazine=Proceedings of the Royal Society B|volume=265|issue= 1394|pages=397–407|pmc=1688905|jstor=50849|doi=10.1098/rspb.1998.0308}}</ref>}}

{{Term|shaft}}
{{defn|''See entry for {{gli|rachis}}''.}}

{{Term|sides}}
{{defn|The {{gli|topography|topographical}} area between the {{gli|breast}} and the {{gli|back}}, stretching from the {{gli|axilla}} (underarm) to the [[Medicine:Iliac crest|Iliac crest]].<ref>{{cite book|last1=Frederick II|first1=(Holy Roman Emperor)|editor-last1=Wood|editor-first1=Casey Albert|editor-last2=Fyfe|editor-first2=Florence Marjorie|title=De Arte Venardi Cum Avibus: Being the De Arte Venandi Cum Avibus of Frederick II of Hohenstaufen|url= https://books.google.com/books?id=TccPuWKAxBkC&pg=PA70|year=1943|publisher=Stanford University Press|isbn=978-0-8047-0374-1|page=72|trans-title=The Art of Falconry}}</ref>}}

{{Birdsong|url=http://www.xeno-canto.org/explore?query=Dacelo|species=the Kookaburra|song1=Cucaburra.ogg|caption song1=The extraordinary {{gli|song}} of the [[Biology:Kookaburra|Kookaburra]]}}
{{Term|song|content=song {{anchor|songs}} }}
{{Main|Biology:Bird vocalization}}
{{defn|A type of bird vocalization associated with [[Biology:Bird#Breeding|courtship and mating]], tending to be longer and more complex than a bird's {{gli|call}}, which serve such functions as giving alarm or keeping members of a [[Biology:Herd|flock]] in contact.<ref name="Voices"/>}}

[[File:Mallard speculum.jpg|thumb|upright=0.8|A male mallard. Note the white-edged, blue and black {{gli|speculum}} seen on the wing.]]
{{Term|speculum|content=speculum {{anchor|speculum feather|speculum feathers|mirror}} }}
{{defn|''Also, '''speculum feathers'''; '''mirror'''.'' A patch of usually brightly coloured feathers, often iridescent, on the inner {{gli|secondaries|secondary remiges}} in a number of duck species,<ref name="Cooper1870">{{cite book|last=Cooper|first=J.G. |editor-last1=Baird|editor-first1=S.F.|title=Ornithology|url=https://books.google.com/books?id=bfURAwAAQBAJ&pg=PA570|year=1870|publisher=Geological Survey of California, J.D. Whitney, State Geologist|isbn=978-5-87984-211-1|page=570}}</ref> though other birds may have them, such as the bright red or orange wing speculum of several parrots from the genus ''[[Biology:Amazona|Amazona]]''.<ref name="Panama">{{cite book|last1=Ridgely|first1=Robert S.|last2=Gwynne|first2=John A. Jr. |year=1989|title=Birds of Panama with Costa Rica, Nicaragua, and Honduras|isbn=978-0-691-08529-6|publisher=Princeton University Press}}</ref>}}

{{Term|spur|content=spur {{anchor|spurs}} }}
{{defn|Outgrowths of [[Biology:Bone|bone]] covered in a sheath of [[Biology:Horn (anatomy)|horn]] which are found on some birds. Spurs are most commonly found on the feet or legs, though some birds possess spurs on the leading edge of the wings.<ref name=Rand>{{cite magazine|last=Rand|first=A.L.|title=On the spurs on birds' wings|magazine=The Wilson Bulletin|volume=66|issue= 2|pages=127–134|url=http://sora.unm.edu/sites/default/files/journals/wilson/v066n02/p0127-p0134.pdf|date=June 1954}}</ref>}}

{{Term|sternum|content=sternum {{anchor|sternum|sterna|breastbones|breastbones|breast bone|breast bones|carinate sternum|carinate sterna|ratite sternum|ratite sterna}} }}
{{defn|''Plural: '''sterna'''.'' The breastbone of a bird. There are two types: i) carinate sterna—appearing in flighted birds, in which the ventral surface is [[Engineering:Keel|keel]]-shaped, which provides ample surface area for attachment of wing muscles used for flight; and ii) ratite sterna—appearing in flightless birds, such as [[Biology:Rhea (bird)|rhea]], in which the ventral surface is flattened.<ref name="Pettingill56">{{Harvnb|Pettingill|1985|p=56}}</ref>}}

{{Term|submoustachial stripe|content=submoustachial stripe {{anchor|submoustachial stripes|submoustachial-stripe|submoustachial-stripes}} }}
{{defn| A usually light stripe of colour between the {{gli|moustachial stripe}} above, and the {{gli|lateral throat-stripe}} below.<ref name="Vinicombe15"/>}}

{{Term|supercilium|content=supercilium {{anchor|supercilia|superciliary line|superciliary lines|eyebrow|eye brow|eyebrows|eye brows}} }}
{{defn|''Plural: '''supercilia'''. Also, '''superciliary line'''; '''eyebrow'''&thinsp;/&thinsp;'''eye brow'''.'' A pale line appearing above the eye of a bird.<ref name="Vinicombe14"/> ''Compare {{gli|eye stripe}}''.}}

{{Term|superior umbilicus|content=superior umbilicus {{anchor|superior umbilicae|distal umbilicus|distal umbilicae}} }}
{{defn|''Also, '''distal umbilicus'''.'' A very small opening on the ventral side (facing toward the bird's skin) of a feather's shaft, marking the distal end of the {{gli|calamus}} and the start of the {{gli|rachis}}. It is a remnant of the epithelial tube used by a bird's body to construct the feather.<ref name="Pettingill29"/> ''Compare: {{gli|inferior umbilicus}}''.}}

{{Term|supraloral|content=supraloral {{anchor|supralorals|supraloral stripe|supraloral stripes|supraloral-stripe|supraloral-stripes}} }}
{{defn|Where a stripe is present only above the {{gli|lores}}, and does not continue behind the eye, it is called a ''supraloral stripe'' or simply ''supraloral'', rather than the {{gli|supercilium}}.<ref>{{cite book|title=Field Guide to the Birds of North America|editor1-first=Jon L.|editor1-last=Dunn |editor2-first=Jonathan |editor2-last=Alderfer|year=2006|publisher=National Geographic Society |location=Washington, D.C. |isbn=978-0-7922-5314-3|page=10}}</ref>}}

{{Term|syrinx}}
{{defn|From the Greek word for pan pipes, σύριγξ, it is the vocal organ of birds. Located at the base of a bird's trachea, it produces sounds without the vocal folds of mammals.<ref name="Terres995">{{harvnb|Terres|1980|p=995}}</ref> As air flows through the syrinx, sound is produced by the vibration of some or all of the ''membrana tympaniformis'' (the walls of the syrinx) and a bar of cartilage connecting the dorsal and ventral extremities, known as the ''[[Biology:Pessulus|pessulus]]''. This sets up a self-oscillating system that regulates the airflow used to create vocalizations. Sound modulation is achieved by varying the tension of muscles connected to the membranes and bronchial openings involved.<ref>{{cite magazine |url=http://jeb.biologists.org/cgi/content/full/205/1/25 |title=Direct observation of syringeal muscle function in songbirds and a parrot|last1=Larsen|first1=O. N.|last2= Goller|first2=Franz|magazine=The Journal of Experimental Biology |volume=205|issue=Pt 1|pages= 25–35 |year=2002 |pmid=11818409}}</ref> The syrinx enables some species of birds (such as [[Biology:Parrot|parrot]]s, [[Biology:Crow|crow]]s and [[Biology:Myna|myna]]s) to mimic human speech. Unlike the mammalian [[Medicine:Larynx|larynx]], the syrinx is located where the trachea forks into the lungs. Thus, [[Biology:Lateralization of bird song|lateralization of bird song]] is possible, and some songbirds can produce more than one sound at a time.<ref>{{cite magazine |last=Suthers |first=R.A. |title=Contributions to birdsong from the left and right sides of the intact syrinx |magazine=Nature |date=October 1990 |volume=347 |issue= 6292 |pages=473–477 |doi=10.1038/347473a0 |bibcode=1990Natur.347..473S}}</ref>}}

{{Glossary end}}

==T==
{{Glossary}}
{{Term|tail|content=tail {{anchor|tails}} }}
{{defn|While the underlying structure of the tail is made up of bone (the pygostyle<ref name="Cade1982">{{cite book|last=Cade|first=Thomas Joseph|title=The falcons of the world|url=https://books.google.com/books?id=55fwAAAAMAAJ|year=1982|publisher=Comstock/Cornell University Press|location=Ithaca, N.Y.|isbn=978-0-8014-1454-1|page=13}}</ref>) and flesh, the term "tail" is most commonly used to refer to the ''feathers'' growing from the region and the shape they form—that is, {{gli|undertail coverts|undertail}} and {{gli|uppertail coverts|uppertail}} coverts and {{gli|rectrices}}, commonly radiating in a fan configuration.<ref name="Pettingill21"/>}}

{{Term|tail coverts}}
{{defn|''See:'' {{gli|undertail coverts}}, {{gli|uppertail coverts}} and {{gli|crissum}}.}}
[[File:Eesti rahvuslind.jpg|thumb|A barn swallow displaying {{gli|tail streamers}}]]
{{Term|tail streamers|content=tail streamers {{anchor|tail streamer|tail-streamer|tail-streamers}} }}
{{defn|The elongated, narrow tips of the {{gli|tail}} seen in some birds.<ref name="MollerBarbosa1998">{{cite magazine|last1=Mo̸ller|first1=A. P.|last2=Barbosa|first2=A.|last3=Cuervo|first3=J. J.|last4=Lope|first4=F. d.|last5=Merino|first5=S.|last6=Saino|first6=N.|title=Sexual selection and tail streamers in the barn swallow|magazine=Proceedings of the Royal Society B: Biological Sciences|volume=265|issue= 1394|year=1998|pages=409–414|issn=0962-8452|doi=10.1098/rspb.1998.0309|pmc=1688894}}</ref> They generally function as a [[Biology:Biological ornament#Sexual selection|sexual ornament]].<ref name="MatyjasiakJabŁoński2001">{{cite magazine|last1=Matyjasiak|first1=Piotr|last2=JabŁoński|first2=Piotr G.|title=Hypothetical mechanisms of the initial evolution of sexually dimorphic tail streamers in Hirundinidae|magazine=Evolution|volume=55|issue= 2|year=2001|pages=446|issn=0014-3820|doi=10.1554/0014-3820(2001)055[0446:HMOTIE]2.0.CO;2|pmid=11308101}}</ref> In the [[Biology:Barn swallow|barn swallow]], this has resulted in tail streamers about {{convert|12|mm|in|abbr=on}} longer than is aerodynamically optimal.<ref name="Buchanan2000">{{cite magazine|last1=Buchanan|first1=K. L.|title=The effect of tail streamer length on aerodynamic performance in the barn swallow|magazine=Behavioral Ecology|volume=11|issue= 2|year=2000|pages=228–238|issn=1465-7279|doi=10.1093/beheco/11.2.228|doi-access=free}}</ref>}}

{{Term|talon|content=talon {{anchor|talons|claw|claws}} }}
{{defn|The claw of a [[Biology:Bird of prey|bird of prey]]; its primary hunting tool.<ref>{{cite magazine|doi=10.1371/journal.pone.0007999|last1= Fowler|first1=D.W.|last2=Freedman|first2=E.A.|last3=Scannella|first3=J.B.|year=2009|title=Predatory Functional Morphology in Raptors: Interdigital Variation in Talon Size Is Related to Prey Restraint and Immobilisation Technique|magazine=PLoS ONE|volume=4|issue= 11|pages=e7999|pmid=19946365|pmc=2776979|editor1-last=Pizzari|editor1-first=Tom|bibcode= 2009PLoSO...4.7999F|doi-access= free}}</ref> The talons are very important; without them, most birds of prey would not be able to catch their food. Some birds also use claws for defensive purposes. [[Biology:Cassowary|Cassowaries]] use claws on their inner toe (digit II) for defence, and have been known to disembowel people. All birds, however, have claws, which are used as general holdfasts and protection for the tip of the digits. The [[Biology:Hoatzin|hoatzin]] and [[Biology:Turaco|turaco]] are unique among extant birds in having functional claws on the thumb and index finger (digit I and II) on the forelimbs as chicks, allowing them to climb trees until the adult plumage with flight feathers develop.<ref name=Parallel>{{cite magazine|last1=Fain|first1=Matthew G.|last2=Houde|first2=Peter|year=2004|title= Parallel radiations in the primary clades of birds|magazine=Evolution|volume=58|issue= 11|pages= 2558–2573|doi=10.1554/04-235|pmid= 15612298|url=http://biology-web.nmsu.edu/~houde/Parallel_radiations.pdf|archive-url=https://web.archive.org/web/20170709030601/http://biology-web.nmsu.edu/~houde/Parallel_radiations.pdf|archive-date=July 9, 2017|url-status=dead}}</ref><ref>{{cite magazine|doi=10.1111/j.1096-3642.1891.tb00045.x|last=Parker|first= W. K.|year=1891|url=https://www.biodiversitylibrary.org/page/31083330 |title=On the Morphology of a Reptilian Bird, ''Opisthocomus hoazin''|magazine=Transactions of the Zoological Society of London|volume=13|pages=43–89|issue= 2}}</ref> However, several birds have a claw- or nail-like structure hidden under the feathers at the end of the hand digits, notably ostriches, emus, ducks, geese and kiwis.<ref>Sir Walter Lawry Buller (1888): A History of the Birds of New Zealand. London [http://www.nzetc.org/tm/scholarly/tei-BulBird-t1-g1-t2-body-d138.html excerpt] from Zealand Electronic Text Centre collection</ref>}}

[[File:Squelette oiseau.svg|thumb|upright=0.8|Pigeon skeleton. Number 8 indicates both left and right {{gli|tarsometatarsus}}]]
{{Term|tarsus|content=tarsus {{anchor|tarsometatarsus|tarsi}} }}
{{defn|''Also defined: '''tarsometatarsus'''.'' The third and most conspicuous portion of the bird's leg, from which the toes spring; the foot.<ref>{{Harvnb|Newton, et al.|1899|p=948}}</ref> In birds, the true [[Biology:Tarsus (skeleton)|tarsus]] has disappeared, with the proximal tarsals having fused with the [[Biology:Tibia#In other animals|tibia]], the centralia having disappeared, and the distal bones having fused with the metatarsals to form a single [[Biology:Tarsometatarsus|tarsometatarsus]] bone, effectively giving the leg a third segment.<ref>{{cite book|last1=Romer|first1=Alfred Sherwood|last2=Parsons|first2=Thomas S.|year=1977|title=The Vertebrate Body|publisher=Holt-Saunders|location=Philadelphia, PA|pages=205–208|isbn=978-0-03-910284-5}}</ref>}}

{{Term|teleoptiles|content=teleoptiles {{anchor|teleoptile}} }}
{{defn|The collective term for all of the feathers of an adult bird.<ref name="Pettingill33">{{Harvnb|Pettingill|1985|p=33}}</ref>}}

{{Term|temporal canthus|content=temporal canthus {{anchor|temporal canthi}} }}
{{defn|The area where the eyelids come together at the posterior corner of the eye (toward the sides of the head), as opposed to the {{gli|nasal canthus}}.<ref name="Pettingill10"/>}}

{{Term|tertiaries|content=tertiaries {{anchor|tertials|tertiary feather|tertiary|humeral feather|humeral feathers}} }}
{{defn|''Also, '''tertials'''; '''tertiary feathers'''; '''humeral feathers'''.'' A type of feather arising in the brachial region, i.e., "proximal to the innermost secondaries", usually growing in a grouping of three to four feathers.<ref name="Proctor54">{{Harvnb|Proctor|Lynch|1998|p=54}}</ref> They are not considered true {{gli|remiges}} as they are not supported by attachment to the corresponding bone—in this case the [[Biology:Humerus|humerus]]. These elongated "true" tertials act as a protective cover for all or part of the folded {{gli|primaries}} and {{gli|secondaries}}, and do not qualify as flight feathers as such.<ref name="Raptors">{{Cite book|last1=Ferguson-Lees |first1=James |last2= Christie |first2= David A. |title=Raptors of the World |publisher=Christopher Helm |location=London |year=2001 |isbn=978-0-7136-8026-3|page=27}}</ref> However, many authorities use the term tertials to refer to the shorter, more symmetrical innermost secondaries of passerines (arising from the olecranon and performing the same function as true tertials) in an effort to distinguish them from other secondaries. The term ''humeral'' is sometimes used for birds such as the albatrosses and pelicans that have a long humerus.<ref>{{cite magazine|magazine=Auk|title=The trouble with tertials|last1=Hickman|first1=Scott| volume=125| issue= 2| year=2008|page=493|doi=10.1525/auk.2008.2408 | doi-access=free}}</ref><ref>{{cite magazine|magazine=The Wilson Bulletin|year=1954 | title=The Pterylosis of the Nestling Coua ruficeps|last1=Berger|first1=A.J.|last2=Lunk|first2=W.A.|pages=119–126|volume=66| issue= 2| url=http://sora.unm.edu/sites/default/files/journals/wilson/v066n02/p0119-p0126.pdf}}</ref>}}

{{Term|throat}}
{{defn|The triangular area of a bird's external anatomy, typically feathered, located between the {{gli|chin}} and the upper part of the {{gli|breast}}.<ref name="Vinicombe14"/>}}

{{Term|thigh}}
{{defn|The {{gli|topography|topographical}} area between the "knee" and the trunk of the body.<ref name="Carnaby11">{{Harvnb|Carnaby|2008|p=11}}</ref>}}

{{Term|tibia|content=tibia {{anchor|tibiae|tibias}} }}
{{defn|The usually feathered part of a bird's leg extending above the foot ({{gli|tarsus}}).<ref name="SchoddeMason1999">{{cite book|last1=Schodde|first1=R|last2=Mason|first2=IJ|title=Directory of Australian Birds: Passerines: Passerines|url=https://books.google.com/books?id=XXbJoaGF36YC&pg=PT1122|year=1999|publisher=Csiro Publishing|isbn=978-0-643-10293-4|page=1122}}</ref>}}

[[File:Mergus merganser -Hogganfield Loch, Glasgow, Scotland -female-8.jpg|thumb|The sawtooth serrations of a [[Biology:Common merganser|common merganser]]'s {{gli|tomia}} help it to hold tight to its fish prey.]]
{{Term|tomia|content=tomia {{anchor|tomium}} }}
{{defn|''Singular: '''tomium'''.'' The cutting edges of the {{gli|upper mandible|upper}} and {{gli|lower mandible|lower}} mandibles.<ref name="Campbell598"/> In most birds, these range from rounded to slightly sharp, but some species have evolved structural modifications that allow them to handle their typical food sources better.<ref name="Stettenheim">{{cite magazine |magazine=Integrative and Comparative Biology |title=The Integumentary Morphology of Modern Birds—An Overview |first=Peter R. |last=Stettenheim |volume=40 |issue= 4 |pages=461–477 |url=http://icb.oxfordjournals.org/content/40/4/461.full.pdf+html |format=PDF |doi=10.1093/icb/40.4.461 |url-status=dead |archive-url=https://web.archive.org/web/20120420052438/http://icb.oxfordjournals.org/content/40/4/461.full.pdf+html |archive-date=April 20, 2012 |year=2000 |doi-access=free }}</ref> Granivorous (seed-eating) birds, for example, have ridges in their tomia, which help the bird to slice through a seed's outer [[Biology:Husk|hull]].<ref>{{cite magazine |doi=10.1016/S1055-937X(99)80036-X |title=Avian gastrointestinal anatomy and physiology |year=1999 |last1=Klasing |first1=Kirk C. |magazine=Seminars in Avian and Exotic Pet Medicine |volume=8 |issue= 2 |pages=42–50}}</ref> Birds in roughly 30 families have tomia lined with tight bunches of very short bristles along their entire length. Most of these species are either {{gli|insectivores}} (preferring hard-shelled prey) or [[Biology:Snail|snail]] eaters, and the brush-like projections may help to increase the coefficient of friction between the mandibles, thereby improving the bird's ability to hold hard prey items.<ref>{{cite magazine |magazine=The Wilson Bulletin |volume=105 |issue= 2 |date=June 1993 |pages=316–324 |title=Scopate Tomia: An Adaptation for Handling Hard-shelled Prey? |first=Kenneth L. |last=Gosner |url=http://sora.unm.edu/sites/default/files/journals/wilson/v105n02/p0316-p0324.pdf }}</ref> Serrations on [[Biology:Hummingbird|hummingbird]] bills, found in 23% of all hummingbird genera, may perform a similar function, allowing the birds to effectively hold insect prey. They may also allow shorter-billed hummingbirds to function as [[Biology:Nectar|nectar]] thieves, as they can more effectively hold and cut through long or waxy flower corollas.<ref>{{cite magazine |magazine=The Auk |volume=111 |issue= 3 | pages=703–710 |title=Serrate Tomia: An Adaptation for Nectar Robbing in Hummingbirds? |first=Juan Francisco |last=Ornelas |url=http://sora.unm.edu/sites/default/files/journals/auk/v111n03/p0703-p0710.pdf }}</ref> In some cases, the colour of a bird's tomia can help to distinguish between similar species. The [[Biology:Snow goose|snow goose]], for example, has a reddish-pink bill with black tomia, while the whole beak of the similar Ross's goose is pinkish-red, without darker tomia.<ref>{{cite book |title=Wildfowl |publisher=Christopher Helm |location=London |year=1988 |pages=143–144 |first1=Steve |last1=Madge |first2=Hilary |last2=Burn |isbn=978-0-7470-2201-5}}</ref>}}

{{Term|topography|content=topography}}
{{defn|The mapping of external features of bird anatomy.<ref name="Pettingill8">{{Harvnb|Pettingill|1985|page=8}}</ref>}}

{{Term|torpor|content=torpor {{anchor|torpors|hypometabolism}} }}
{{defn|''Also, '''hypometabolism'''.'' An energy-conserving strategy used by some small birds [under {{convert|100|g|oz|abbr=on}}] in which they become inactive and unreactive to external stimuli, and reduce their [[Biology:Metabolism|metabolism]] below their normal respiration and heart rate, causing decreases in body temperature by an average of {{convert|4|-|35|C|F}}.  Two types of torpor are recognized. In one type, such as in [[Biology:Hummingbird|hummingbird]]s, torpor may be entered on a daily basis and last only a few hours; other behaviours, such as foraging, continue during non-torpor periods. For other species, torpor may only be entered during cold conditions or when food becomes limited, but may persist for weeks or even months. The extent of unresponsiveness during torpor can be pronounced. A hummingbird in deep torpor, for example, with a body temperature of {{convert|18|C|F}}, will not respond to a variety of external stimuli, such as attempts to push it from a perch; only the locking reflex of the feet stops the bird from falling.  Torpor has been reported in eight [[Biology:Order|orders]] of birds.<ref>{{cite magazine|last=Schleucher|first=Elke|title=Torpor in birds: taxonomy, energetics, and ecology|magazine=Physiological and Biochemical Zoology|volume=77|issue= 6|year=2004|pages=942–949|doi=10.1086/423744|pmid=15674768}}</ref><ref>{{cite magazine|last=Brigham|first=R. Mark|title=Daily torpor in a free-ranging goatsucker, the common poorwill (Phalaenoptilus nuttallii)|magazine=Physiological Zoology|volume=65|issue= 2|year=1992|pages=457–472|jstor=30158263|doi=10.1086/physzool.65.2.30158263}}</ref>}}

{{Glossary end}}

==U==
{{Glossary}}
{{Term|undertail coverts|content=undertail coverts {{anchor|undertail covert|undertail-coverts|undertail-covert|under tail covert|under-tail covert|under-tail-covert|under tail-covert|under tail coverts|under-tail coverts|under-tail-coverts|under tail-coverts}} }}
{{defn|{{gli|Covert feathers}} covering the base of the {{gli|tail}} on its underside.<ref name="Pettingill21"/> ''Compare: {{gli|uppertail coverts}}; contrast {{gli|wing coverts}}.''}}

[[File:Underwing.svg|thumb|{{gli|Underwing}} of bird showing feather nomenclature: 1&nbsp;{{gli|axillaries}}, 2&nbsp;margin (marginal underwing coverts), 3&nbsp;{{gli|lesser coverts|lesser underwing coverts}}, 4&nbsp;{{gli|median covert|median underwing coverts}} (secondary coverts), 5&nbsp;{{gli|greater coverts|greater underwing coverts}} (secondary coverts), 6&nbsp;carpal joint, 7&nbsp;lesser underwing primary coverts, 8&nbsp;greater underwing primary coverts, 9&nbsp;{{gli|secondaries}}, 10&nbsp;{{gli|primaries}}]]
{{Term|underwing|content=underwing {{anchor|underwings|under-wing|under-wings|under wing|under wings}} }}
{{defn|The bottom side of a bird's wing; the hidden surface of the wing when it is folded.<ref>{{Cite OED|Underwing}}</ref> ''Compare: {{gli|upperwing}}.''}}

{{Term|upper mandible|content=upper mandible {{anchor|maxilla|upper mandibles|upper maxilla}} }}
{{defn|''Also, '''maxilla'''.'' The upper part of a bird's {{gli|bill}} or beak, roughly corresponding to the upper jaw of mammals, it is supported by a three-pronged [[Biology:Bone|bone]] called the intermaxillary. The upper prong of this bone is embedded into the forehead, while the two lower prongs attach to the sides of the [[Biology:Skull|skull]]. At the base of the upper mandible a thin sheet of nasal bones is attached to the skull at the nasofrontal hinge, which gives mobility to the upper mandible, allowing it to move upwards and downwards.<ref name="Proctor66"/> The outer surface is covered in a thin, horny sheath of [[Biology:Keratin|keratin]] called {{gli|rhamphotheca}}<ref name="Proctor66"/><ref name="Gill148"/> specially called {{gli|rhinotheca}} in the upper mandible.<ref name="Campbell47"/> ''Compare: {{gli|lower mandible}}''.}}

{{Term|upper parts|content=upper parts {{anchor|upper-parts|upperparts}} }}
{{defn|''Also, '''upper-parts''' and '''upperparts'''.'' The {{gli|topography|topographical}} areas above the eyes of a bird (generally not including the {{gli|eyestripe}}, if any) and through all of a bird's upper surface, including the "{{gli|crown}}, {{gli|mantle}}, {{gli|back}}, {{gli|tertials}} and {{gli|inner wing-coverts}}",<ref name="RAOU1991">{{cite magazine|magazine=RAOU Newsletter|volume=21|issue= 4|title=Wing Span| year=2011| page=17 |oclc=23961486}}</ref> although the term is sometimes used more inclusively, for all features from the bill to the tail.<ref name="Wheelock">{{cite book|title=Birds of California: An Introduction to More than 300 Common Birds of the State and Adjacent Islands| location=Chicago|last=Wheelock|first=Irene Grosvenor|page=15|publisher=A.C. McClurg|date=1904|url=https://books.google.com/books?id=RZoaAAAAYAAJ&pg=PR15|oclc=2064174}}</ref> ''Compare: {{gli|under parts}}.''}}

{{Term|under parts|content=under parts {{anchor|under-parts|underparts|lower parts|lower-parts|lowerparts}} }}
{{defn|''Also, '''under-parts'''; '''underparts'''; '''lower parts'''; '''lower-parts'''; '''lowerparts'''.'' All {{gli|topography|topographical}} areas on the underside or "under surface" of a bird,<ref name="Wheelock"/> i.e., from the {{gli|chin}} to the underside end of the tail (on the trunk and thus not including the legs). ''Compare {{gli|upper parts}}.''}}

{{Term|uppertail coverts|content=uppertail coverts {{anchor|uppertail covert|uppertail-coverts|uppertail-covert|upper tail covert|upper-tail covert|upper-tail-covert|upper tail-covert|upper tail coverts|upper-tail coverts|upper-tail-coverts|upper tail-coverts}} }}
{{defn|{{gli|Covert feathers}} covering the base of the {{gli|tail}} on its upperside.<ref name="Pettingill21"/> Sometimes these coverts are more specialized. The "tail" of a peacock is actually very elongated uppertail coverts.<ref name="Mobley295"/> ''Compare {{gli|undertail coverts}}; contrast {{gli|wing coverts}}.''}}

{{Term|upperwing|content=upperwing {{anchor|upperwings|upper-wing|upper-wings|upper wing|upper wings}} }}
{{defn| The top, or upper, side of a bird's wing.<ref name="nebraskabirdlib">{{cite web|title=Glossary of Bird Terms|url=http://www.nebraskabirdlibrary.org/resources/glossary-of-bird-terms/|website=www.nebraskabirdlibrary.org|access-date=March 26, 2017}}</ref> ''Compare: {{gli|underwing}}.''}}

{{Term|uropygial gland|content=uropygial gland {{anchor|uropygial glands|uropygial|preen gland|preen glands|oil gland|oil glands}} }}
{{defn|''Also, '''preen gland'''; '''oil gland'''.'' A gland found at the {{gli|rump}}, at the base of the {{gli|tail}} that produces a waxy secretion made up of oils, fatty acids, fats and water that the majority of birds use in daily {{gli|preening}} of their feathers. Though feathers {{gli|moult}} periodically, they are inert structures without a nourishment system and would deteriorate rapidly without such application during preening. The applied waxy secretion aids in waterproofing, helps maintain feather moistness to keep them from becoming brittle and maintain flexibility, and is thought to promote the growth of nonpathogenic fungi, to deter feather lice and some forms of keratin-eating fungi and bacteria. The gland, a bilobed structure, is usually surrounding by a tuft of downy feathers that can act like a wick for the secreted oils.<ref name="Gill102">{{Harvnb|Gill|1995|p=102}}</ref>}}

{{Term|uropygium}}
{{defn|''See {{gli|rump}}.''}}

{{Glossary end}}

==V==
{{Glossary}}
{{term|vagrant}}
{{defn|Descriptive of a bird found outside its species' or subspecies' normal migration range or distribution area.<ref>{{Cite OED|vagrant}}</ref>}}

{{Term|vane|content=vane {{anchor|vanes|vexillum|vaxillum|vexilla|outer vane|outer vanes|outer-vane|outer-vanes|inner vane|inner vanes|inner-vane|inner-vanes}} }}
{{defn|''Also, '''vexillum''' – plural: '''vexilla'''.'' The weblike expanse of flexible barbs, more or less interconnected by the {{gli|hooklets}} of the {{gli|barbules}}, extending from each side of the distal part of the feather's shaft known as the {{gli|rachis}}. One side of the vane, called the outer vane, overlaps the inner vane side of the feather next to it.<ref name="Pettingill32"/>}}

{{Term|vanule}}
{{defn|The collective term for all of the {{gli|barbules}} branching from the {{gli|ramus}} of a feather's {{gli|barb}}.<ref name="Chandler252"/>}}

{{Term|vaned feather|content=vaned feather {{anchor|vaned feathers}} }}
{{defn|A classification term for pennaceous feathers (aka contour feathers) that clothe the outside of a bird's body.<ref name="Alderfer2012">{{cite book|last=Alderfer|first=Jonathan K.|title=Bird-watcher's Bible: A Complete Treasury: Science, Know-how, Beauty, Lore|url=https://books.google.com/books?id=FkT761I4150C&pg=PT33|year=2012|publisher=National Geographic|isbn=978-1-4262-0964-2|page=32}}</ref> It refers to the ''{{gli|vane|vaned}}'' property of such feathers, i.e., having a flattened weblike expanse of flexible {{gli|barbs}}, more or less interconnected by the {{gli|hooklets}} of the {{gli|barbules}}, extending from each side of the distal part of the feather's shaft known as the {{gli|rachis}}. They make up one of three broad classes of feathers, the others being {{gli|down feathers}} (which lie underneath vaned feathers, if present), and the hairlike {{gli|filoplumes}}.<ref name="Pettingill32"/>}}

{{Term|vent|content=vent {{anchor|vents}} }}
{{defn|The external opening of the {{gli|cloaca}}.<ref name="Kahn2007">{{cite book|last=Kahn|first=Cynthia M.|title=The Merck/Merial Manual For Pet Health: The complete health resource for your dog, cat, horse or other pets – in everyday language|url=https://books.google.com/books?id=eE2IvM10IX4C&pg=PA849|year=2007|publisher=Simon and Schuster|isbn=978-0-911910-99-5|page=849}}</ref>}}

{{Term|vent pecking}}
{{main|Biology:Vent pecking}}
{{defn|An [[Biology:Abnormal behaviour of birds in captivity|abnormal behaviour]] of birds in captivity, performed primarily by commercial egg-laying [[Biology:Chicken|hens]], characterized by pecking damage to the {{gli|cloaca}}, the surrounding skin and underlying tissue.<ref name="Sherwin, 2010">Sherwin, C.M., (2010). The welfare and ethical assessment of housing for egg production. In ''The Welfare of Domestic Fowl and Other Captive Birds'', I.J.H. Duncan and P. Hawkins (eds), Springer, pp. 237–258</ref> Vent pecking frequently occurs immediately after an egg has been laid when the cloaca often remains partly everted exposing the mucosa.<ref>{{cite magazine|magazine=Applied Animal Behaviour Science|last1=Potzsch|first1=C. J.|last2=Lewis|first2=K.|last3=Nicol|first3=C. J.|last4=Green|first4=L. E.|year=2001|title=A cross-sectional study of the prevalence of vent pecking in laying hens in alternative systems and its associations with feather pecking, management and disease|volume=74|issue= 4|pages=259–272|doi=10.1016/S0168-1591(01)00167-8}}</ref>}}

{{Glossary end}}

==W==
{{Glossary}}
[[File:Flickr - Rainbirder - Bearded Bellbird (Procnias averano) male calling.jpg|thumb|An adult male bearded bellbird {{gli|calling}} in the Arima Valley of Trinidad. Note the beard-like {{gli|wattles}} sprouting from its {{gli|chin}} and {{gli|throat}} area, for which the bird is named.]]
{{Term|wattle|content=wattle {{anchor|wattles|dewlap|dewlaps|rictal wattle|rictal wattles}} }}
{{defn|''Also, '''dewlap'''; '''lappet'''; '''palearia'''. Specialized type: '''rictal wattle'''.'' A type of {{gli|caruncle}}, the wattle is a flap or [[Biology:Lobe (anatomy)|lobe]] of flesh, often of a vivid colour, that hangs from the head of some birds, often from the chin or throat.<ref>{{Cite OED|Wattle}}</ref><ref name="CruickshankCruickshank1976">{{cite book|last1=Cruickshank|first1=Allan D. |last2=Cruickshank|first2=Helen Gere |title=1001 Questions Answered about Birds|url=https://books.google.com/books?id=96KxUxvA4H4C&pg=PA97|year=1976|publisher=Courier Corporation|isbn=978-0-486-23315-4|page=97}}</ref> When found at the corner of the mouth, they may be called ''rictal wattles'', such as in [[Biology:Masked lapwing|masked lapwing]]s.<ref name="Kochan1995">{{cite book|last=Kochan|first=Jack B. |title=Bills & mouths|url=https://books.google.com/books?id=ybRPAAAAYAAJ|date=September 1995|publisher=Stackpole Books|isbn=978-0-8117-3057-0|page=12}}</ref> Birds with wattles include [[Biology:Turkey (bird)|turkey]]s, [[Biology:Guineafowl|guineafowl]]s, [[Biology:Northern cassowary|northern cassowaries]], [[Biology:Black-faced ibis|black-faced ibis]]es, [[Biology:North Island kōkako|North Island kōkako]]s, [[Biology:Wattled starling|wattled starling]]s (males, when in {{gli|nuptial plumage}}) and male [[Biology:Bearded bellbird|bearded bellbird]]s, with the last having startling, beard-like wattles.<ref name="StarkSclater1900">{{cite book | last1=Stark | first1=Arthur Cowell | title=The Birds of South Africa Vol. 1 |url=https://biodiversitylibrary.org/page/19014806 | year=1900 | volume=1 | place=London | publisher=R. H. Porter |page=23}}</ref><ref name="Kricher2015">{{cite book|last=Kricher|first=John |title=A Neotropical Companion: An Introduction to the Animals, Plants, and Ecosystems of the New World Tropics. Illustrated by Andrea S. LeJeune|url=https://books.google.com/books?id=b2sZBgAAQBAJ&pg=PA273|date=February 18, 2015|publisher=Princeton University Press|isbn=978-1-4008-6691-5|page=273}}</ref>}}

{{term|whiffling}} 
{{defn|A flight behaviour in which a bird rapidly descends with a zig-zagging, side-slipping motion. During whiffling, some birds invert the aerodynamic mechanics of their bodies that normally provide [[Physics:Lift (force)|lift]]—flying by turning their bodies upside down but with their necks twisted 180 degrees to keep their heads in a normal flying position—resulting in a rapid plummet, before a quick arrest of the fall by resumption of a normal flying orientation.<ref>{{cite magazine|author-last1=Ogilvie |author-first1=M.A. |author-last2=Wallace|author-first2=D.I.M.|title=Field identification of grey geese|magazine=British Birds|volume=68|year=1975|pages=57–67}}</ref><ref>{{cite web|publisher=New Scientist TV|last=Ceurstemont|first=Sandrine|url=https://www.newscientist.com/blogs/nstv/2012/01/first-slow-mo-video-of-goose-flying-upside-down.html|date=January 25, 2012|access-date=April 19, 2017|title=Goose flying upside down captured in slow-mo movie}}</ref><ref name="Attenborough1998">{{cite book|last=Attenborough|first=David |title=The life of birds|url=https://books.google.com/books?id=HO0PAQAAMAAJ|date=September 24, 1998|publisher=BBC|isbn=978-0-563-38792-3|page=49}}</ref>}}

[[File:Pine Siskin Female (10743)-Relic38.JPG|thumb|A female pine siskin with white {{gli|wing bars}}.]]
{{Term|wing bar|content=wing bar {{anchor|wing-bar|wing bars|wing-bars|wingbar|wingbars}} }}
{{defn|A stripe found on the {{gli|upperwing}} that is created by the contrast of the tips of the primary and secondary coverts.<ref name="DunnAlderfer2006">{{cite book|last1=Dunn|first1=Jon Lloyd |last2=Alderfer|first2=Jonathan K. |title=National Geographic Field Guide to the Birds of North America|url=https://books.google.com/books?id=gA-rfkTZi1YC&pg=PA12|year=2006|publisher=National Geographic Books|location=Washington D.C.|isbn=978-0-7922-5314-3|page=12}}</ref> This feature may disappear when a bird {{gli|moults}} and takes on a different seasonal {{gli|plumage}}.<ref name="Bengal1872">{{cite book|last1=Brooks|first1=W.E.|last2=Etáwah|first2=C.E.|editor=The Honorary Secretaries|title=Proceedings of the Asiatic Society of Bengal: 1872 – Brooks on Imperial Eagles of India|url=https://books.google.com/books?id=5s5TAAAAcAAJ&pg=PA65|year=1872|publisher=C.B. Lewis, Baptist Mission Press|location=Calcutta|page=65}}</ref> Wing bars often occur in pairs.<ref name="Floyd2008_498">{{harvnb|Floyd|2008|p=498}}</ref> ''Contrast: {{gli|speculum}}''.}}

{{Term|wing clipping|content=wing clipping {{anchor|wing trimming}} }}
{{defn|''Also, '''wing trimming'''.'' The controversial practice of trimming a bird's {{gli|primaries|primary wing feathers}} or {{gli|remiges}} so that it is not fully flight-capable, until it grows replacement feathers during its next {{gli|moult}}.<ref>{{cite web|url=https://theparrotsocietyuk.org/site/index.php/parrot-information/veterinary-advice/wing-clipping/|last=Jones|first=Alan K|title=Wing Clipping in Pet Birds - a study and comparison of techniques|publisher=The Parrot Society UK|access-date=December 21, 2020}}</ref> If it is performed correctly, it is a painless procedure.<ref name="Hess">{{cite web |last1=Hess |first1=Laurie, DVM |title=How to Clip a Bird's Wings |url=https://www.petmd.com/bird/grooming/how-clip-birds-wings |website=PetMD |date=February 27, 2017|access-date=22 December 2020}}</ref> Nevertheless, the practice can cause injury, e.g., hemorrhaging as the result of {{gli|blood feathers}} being accidentally trimmed.<ref name="Speer2015">{{cite book|last=Speer|first=Brian |title=Current Therapy in Avian Medicine and Surgery|url=https://books.google.com/books?id=tclQCwAAQBAJ|year=2015|publisher=Elsevier Health Sciences|isbn=978-0-323-24367-4|page=700}}</ref>}}

[[File:chicken wing.svg|thumb|Topside of a chicken wing showing all major feather groups]]
{{Term|wing coverts|content=wing coverts {{anchor|wing covert|wing-covert|wing-coverts|upperwing coverts|underwing coverts|secondary coverts|primary coverts|greater primary coverts|greater secondary coverts|median primary coverts|median secondary coverts|lesser primary coverts|lesser secondary coverts|lesser underwing coverts|lesser underwing primary coverts|median underwing coverts|greater underwing primary coverts|greater underwing coverts|upperwing covert|underwing covert|secondary covert|primary covert|greater primary covert|greater secondary covert|median primary covert|median secondary covert|lesser primary covert|lesser secondary covert|lesser underwing covert|lesser underwing primary covert|median underwing covert|greater underwing primary covert|greater underwing covert|lesser covert|lesser coverts|greater covert|greater coverts|median|median coverts|median covert}} }}
{{defn|''Also defined: '''upperwing coverts'''; '''underwing coverts'''; '''secondary coverts'''; '''primary coverts'''; '''greater''' ('''primary'''-/'''secondary'''-) '''coverts'''; '''median''' ('''primary'''-/'''secondary'''-) '''coverts'''; '''lesser''' ('''primary'''-/'''secondary'''-) '''coverts''' (the last being also called '''bow coverts''').''<br />{{gli|Covert feathers}} found on a bird's {{gli|wing}}. There are a number of classes and subclasses. The {{gli|upperwing}} coverts fall into two groups: those on the {{gli|inner wing}}, which overlay the [[Biology:Flight feather#Secondaries|secondary flight feathers]], are known as the secondary coverts, and those on the {{gli|outer wing}}, which overlay the [[Biology:Flight feather#Primaries|primary flight feathers]], are known as the primary coverts. Within each group, the feathers form a number of rows. The feathers of the outermost, largest, row are termed greater (primary-/secondary-) coverts; those in the next row are the median (primary-/secondary-) coverts, and any remaining rows are termed lesser (primary-/secondary-) coverts. The {{gli|underwing}} has corresponding sets of coverts (the names upperwing coverts and underwing coverts are used to distinguish the corresponding sets). In addition, the front edge of the wing is covered with a group of feathers called the marginal coverts. Within each group of wing coverts, the rows of feathers overlap each other like roof tiles (the greater coverts are overlain by the median coverts, which in turn are overlain by the outermost row of lesser coverts, and so on).<ref name="Pettingill16-21">{{Harvnb|Pettingill|1985|pages=16–21}}</ref> ''See also: {{gli|axillaries}}; {{gli|ear coverts}}; {{gli|wing lining}} (marginal coverts).''}}

{{Term|wing formula|content=wing formula {{anchor|wing formulae}} }}
{{defn|A mathematical classification of the shape of the distal end of a bird's wing. It can be used to help distinguish between species with similar {{gli|plumages}}, and thus is particularly useful for those who ring (band) birds. To determine a bird's wing formula, the exposed distance between the tip of the most distal {{gli|primary}}, and the tip of its {{gli|greater covert}} (the longest of the feathers that cover and protect the shaft of that primary), is measured in millimetres. In some cases, this results in a positive number (e.g., the primary extends beyond its greater covert), while in other cases it is a negative number (e.g., the primary is completely covered by the greater covert, as happens in some passerine species). Next, the longest primary feather is identified, and the differences in millimetres is measured between: i) the length of that primary; ii) that of all of the remaining primaries; and iii) of the longest secondary. If any primary shows a notch or {{gli|emargination}}, this is noted, and the distance between the feather's tip and any notch is measured, as is the depth of the notch. All distance measurements are made with the bird's wing closed, so as to maintain the relative positions of the feathers. While there can be considerable variation across members of a species—and while the results are obviously impacted by the effects of {{gli|moult}} and feather regeneration—even very closely related species show clear differences in their wing formulae.<ref name="Campbell656"/>}}

{{Term|wing lining|content=wing lining {{anchor|wing linings|winglining|winglinings|wing-lining|wing-linings|marginal coverts|marginal-coverts|marginal-coverts|median primary covert|median secondary covert|median primary coverts|median secondary coverts}} }}
{{defn|''Also, '''marginal coverts'''.'' A grouping of very soft {{gli|covert feathers}} lining the anterior edge of the underside of the wing. Though the wing lining is composed of rows of these feathers, they are smooth in appearance such that it is often impossible to see the demarcation of the rows solely by eye.<ref name="Campbell60"/>}}

{{Term|wings|content=wings {{anchor|wing|elliptical wing|elliptical wings|high speed wing|high speed wings|high aspect ratio wing|high aspect ratio wings|soaring wing|soaring wings}} }}
{{defn|''Wing types defined: '''elliptical'''; '''high speed'''; '''high aspect ratio'''; '''soaring'''.'' The bird's forelimbs that are the key to flight. Each wing has a central axis, composed of three limb bones: the [[Biology:Humerus|humerus]], [[Biology:Ulna|ulna]] and [[Biology:Radius (bone)|radius]]. The hand, or ''manus'', which ancestrally was composed of five digits, is reduced to three digits (digit II, III and IV or I, II, III depending on the scheme followed<ref>Baumel, J.J. (1993) ''Handbook of Avian Anatomy: Nomina Anatomica Avium''. 2nd Ed. Nuttall Ornithological Club. Cambridge, MA</ref>), which serves as an anchor for the {{gli|primaries}}, one of two groups of [[Biology:Flight feather|flight feather]]s responsible for the wing's airfoil shape. The other set of flight feathers, behind the carpal joint on the ulna, are called the {{gli|secondaries}}. The remaining feathers on the wing are known as {{gli|coverts}}, of which there are three sets. The wing sometimes has vestigial claws. In most species these are lost by the time the bird is adult (such as the highly visible ones used for active climbing by [[Biology:Hoatzin|hoatzin]] chicks), but claws are retained into adulthood by the [[Biology:Secretarybird|secretarybird]], [[Biology:Screamer|screamer]]s, [[Biology:Heliornithidae|finfoots]], [[Biology:Ostrich|ostrich]]es, several [[Biology:Swift (bird)|swift]]s and numerous others, as a local trait, in a few specimens. Bird wings are generally grouped into four types: i) elliptical wings—short, rounded and having a low aspect ratio, they allow for tight maneuvering in confined spaces such as might be found in dense vegetation. They are common in forest raptors, many migratory species of [[Biology:Passerine|passerine]]s, and in species such as [[Biology:Pheasant|pheasant]]s and [[Biology:Partridge|partridge]]s that use a rapid take-off to evade predators. ii) High speed wings—short, pointed wings that, when combined with a heavy wing loading and rapid wingbeats, provide an energetically expensive high speed, as used by the bird with the fastest wing speed, the peregrine falcon. Most [[Biology:Duck|duck]]s and [[Biology:Auk|auk]]s have this type of wing but use the configuration for a different purpose, to "fly" underwater. iii) High aspect ratio wings—typified by low wing loading and being far longer than they are wide, they are used for slower flight, which may take the form of almost hovering (as used by [[Biology:Kestrel|kestrel]]s, [[Biology:Tern|tern]]s and [[Biology:Nightjar|nightjar]]s), or in soaring and gliding flight, particularly the dynamic soaring used by seabirds, which takes advantage of wind speed variation at different altitudes ([[Physics:Wind shear|wind shear]]) above ocean waves to provide lift. iv) Soaring wings with deep slots—common in larger species of inland birds, such as [[Biology:Eagle|eagle]]s, [[Biology:Vulture|vulture]]s, [[Biology:Pelican|pelican]]s and [[Biology:Stork|stork]]s. The slots at the end of the wings, between the primaries, reduce the induced drag and [[Physics:Wingtip vortices|wingtip vortices]], while the shorter size of the wings aids in takeoff (high aspect ratio wings require a long taxi to get airborne).<ref>{{Harvnb|Feduccia|1999|pages=16–18}}</ref>}}
[[File:Bee hummingbird (Mellisuga helenae) adult male in flight-cropped.jpg|thumb|Male bee hummingbird in flight; the bird with the smallest {{gli|wingspan}} at {{convert|6.6|cm|in|abbr=on}}.]]

{{Term|wingspan|content=wingspan {{anchor|wingspans|wing span|wing spans}} }}
{{defn|The distance between each of the tips of the fully extended {{gli|wings}}.<ref name="birdacademy">{{cite web|title=Bird Academy's A-to-Z Glossary of Bird Terms|url=https://academy.allaboutbirds.org/bird-academys-a-to-z-glossary-of-bird-terms/|access-date=March 19, 2017|date=September 9, 2016}}</ref> The living bird species with the largest wingspan is the [[Biology:Wandering albatross|wandering albatross]], typically ranging from {{convert|2.5|to|3.5|m|ftin|abbr=on}}.<ref name="Elphick2007">{{cite book|last=Elphick|first=Jonathan |title=The Atlas of Bird Migration: Tracing the Great Journeys of the World's Birds|url=https://books.google.com/books?id=j91I9I4pq20C&pg=PT159|year=2007|publisher=Struik|isbn=978-1-77007-499-6|pages=154–155}}</ref> In contrast, the living bird species with the smallest wingspan is the [[Biology:Bee hummingbird|bee hummingbird]] (also the smallest bird overall) with a wingspan of just {{convert|6.6|cm|in|abbr=on}}.<ref name="Williams94">{{cite book|last=Williams|first=Ernest H. Williams Jr. |title=The Nature Handbook: A Guide to Observing the Great Outdoors|url=https://books.google.com/books?id=VoV7CclhNJcC&pg=PA94|year=2005|publisher=Oxford University Press|isbn=978-0-19-972075-0|page=94}}</ref>}}

{{Term|winter plumage}}
{{defn|''See {{gli|basic plumage}}.''}}

{{Glossary end}}

==Z==
{{Glossary}}
{{Term|zygodactylous|content=zygodactylous|zygodactyl|zygodactyl foot|zygodactyl feet|yoke-toed|zygodactylous foot|zygodactylous feet|heterodactylous|heterodactyl|heterodactyl foot|heterodactyl feet|heterodactylous foot|heterodactylous feet}}
{{defn|''Also, '''yoke-toed'''. Also defined: '''heterodactylous'''.'' Descriptive of tetradactyl (four-toed) birds in which the architecture of the foot consists of two toes projecting forward and two toes projecting backward, such as in [[Biology:Parrot|parrot]]s, [[Biology:Woodpecker|woodpecker]]s and [[Biology:Cuckoo|cuckoo]]s. In most birds with zygodactylous feet, the forward projecting toes are the second and third toes and the backward projecting toes are the fourth toe and {{gli|hallux}}. However, in [[Biology:Trogon|trogon]]s alone, the third and fourth toes are in front, and the second and hallux are behind. This arrangement is sometimes separately designated, and termed ''heterodactylous''.<ref name="Gill59–61"/><ref>{{Harvnb|Coues|1890|p=187}}</ref>}}

{{Glossary end}}

==See also==
* [[Biology:Glossary of dinosaur anatomy|Glossary of dinosaur anatomy]]


== Explanatory footnotes ==
{{notelist}}

== Citations ==
{{Reflist|30em}}

== Bibliography ==
* {{cite book|last=Bird|first=David Michael|title=The Bird Almanac: A Guide to Essential Facts and Figures of the World's Birds|url=https://books.google.com/books?id=HTX6BatQFDgC&pg=PA4|year=2004|publisher=Firefly Books|isbn=978-1-55297-925-9}}
* {{cite book|editor-last=Campbell|editor-first=Bruce|editor2-last=Lack|editor2-first= Elizabeth|title=A Dictionary of Birds|year=1985|publisher=T and A D Poyser|location=Carlton, England|isbn=978-0-85661-039-4 }}
* {{cite book|last=Carnaby|first=Trevor|title=Beat about the Bush: Birds |url=https://books.google.com/books?id=hh11gLdZyDgC&pg=PA11|year=2008|publisher=Jacana Media|isbn=978-1-77009-241-9|location=Johannesburg}}
* {{cite book|last1=Chandler|first1=Asa C.|year=1916|title=A study of the structure of feathers, with reference to their taxonomic significance|publisher=University of California Press|location=Berkeley, CA|url=https://archive.org/stream/studyofstructure00chan#page/n0/mode/1up}}
* {{cite book |last1=Cheke |first1=Robert A. |last2=Mann |first2=Clive F. |last3=Allen |first3=Richard |name-list-style=amp |title=Sunbirds: A Guide to the Sunbirds, Flowerpeckers, Spiderhunters and Sugarbirds of the World |location=London |publisher=Christopher Helm |year=2001 |isbn=978-1-873403-80-8}}
* {{cite book|title=Handbook of Field and General Ornithology|first=Elliott |last=Coues |year=1890 |publisher=Macmillan and Co|location=London|url=https://archive.org/details/in.ernet.dli.2015.32046|oclc=263166207}}
* {{cite book |editor-last=del Hoyo|editor-first= Josep|editor2-last=Elliott|editor2-first=Andrew|editor3-last=Sargatal |editor3-first=Jordi |year=1992|title=Handbook of the Birds of the World, Volume 1: Ostrich to Ducks|publisher=Lynx Edicions|location=Barcelona|isbn=978-84-87334-10-8 |title-link= Handbook of the Birds of the World}}
* {{cite book|last1=Ehrlich|first1=Paul R.|last2=Dobkin|first2= Darryl A.|last3=Wheye|first3=Darryl|last4=Pimm|first4=Stuart L.|title=The Birdwatcher's Handbook|year=1994|publisher=Oxford University Press|isbn=978-0-19-858407-0|url=https://archive.org/details/birdwatchershand00ehrl |url-access=registration}}
*{{cite book|last=Elphick|first=Jonathan|year=2016|publisher=Firefly Books|title=Birds: A Complete Guide to their Biology and Behavior|location=Buffalo, New York|isbn=978-1-77085-762-9}}
* {{cite book|last=Feduccia|first=Alan|title=The Origin and Evolution of Birds|url=https://books.google.com/books?id=8QRKV7eSqmIC&pg=PA16|year=1999|publisher=Yale University Press|isbn=978-0-300-07861-9}}
* {{cite book|last=Floyd|first=Ted|title=Smithsonian Field Guide to the Birds of North America|url=https://books.google.com/books?id=Nn3Hz6OwjTAC|year=2008|publisher=HarperCollins|isbn=978-0-06-112040-4}}
* {{cite book|title=Ornithology|first=Frank B.|last=Gill|edition=2|year=1995|publisher=W. H. Freeman and Company |location=New York, NY|isbn=978-0-7167-2415-5}}
* {{cite book|title=Gulls of the Americas|first=Steve N. G.|last=Howell|year=2007|publisher=Houghton Mifflin Company |location=New York |isbn=978-0-618-72641-7}}
* {{cite book|title=Form and Function in Birds, volume 3|editor1-first=Anthony Stuart |editor1-last=King|editor2-first=John |editor2-last=McLelland|year=1985|publisher=Academic Press|location=London, UK|isbn=978-0-12-407503-0}}
* {{cite book|last1=Lovette|first1=Irby J.|last2=Fitzpatrick|first2=John W.|title=Handbook of Bird Biology|url=https://books.google.com/books?id=OiaNDAAAQBAJ|year=2016|publisher=Wiley|isbn=978-1-118-29104-7}}
* {{cite book|last1=Newton|first1=Alfred|last2=Gadow|first2=Hans Friedrich|last3=Lydekker|first3=Richard|last4=Roy| first4=Charles Smart|last5=Shufeldt|first5=Robert Wilson|title=A Dictionary of Birds|url=https://books.google.com/books?id=2u8ZAAAAYAAJ|year=1899|publisher=A. and C. Black|location=London|ref={{harvid|Newton, et al.|1899}}|oclc=623393918}}
* {{cite book|last1=Mobley|first1=Jason A.|last2=Brewer|first2=Duncan|last3=Elphick| first3=Jonathan|last4=Hoare|first4=Ben|last5=Unwin |first5=Mike|last6=Woodward|first6=John| title=Birds of the World|url=https://books.google.com/books?id=gccfdvSUTg4C|year=2008|publisher=Marshall Cavendish|isbn=978-0-7614-7775-4|location=Tarrytown, NY|display-authors=et al.|ref={{harvid|Mobley, et al.|2008}}}}
* {{cite book|first1=Olin Sewall Jr. |last1=Pettingill|year=1985|title=Ornithology in Laboratory and Field|publisher=Academic Press|isbn=978-0-12-552455-1|location=Orlando, FL|url=https://books.google.com/books?id=JE22s15ZqzsC}}
* {{cite book|last=Pettingill|first=Olin Sewall Jr. |title=Ornithology in Laboratory and Field|url=https://books.google.com/books?id=livLBAAAQBAJ|year=2013|publisher=Elsevier|isbn=978-1-4832-6311-3}}
* {{cite book|title=Manual of Ornithology: Avian Structure and Function |first1=Noble S. |last1=Proctor |first2=Patrick J.|last2=Lynch|year=1998|publisher=Yale University Press|location=New Haven, CT|isbn=978-0-300-07619-6}}
* {{cite book|last=Roots|first=Clive|title=Flightless Birds|url=https://books.google.com/books?id=7PQD-0dYJLgC|year=2006|publisher=Greenwood Publishing Group|isbn=978-0-313-08394-5|location=Westport, CT}}
* {{cite book|title=Essential Ornithology|url=https://archive.org/details/Essential_Ornithology_by_Graham_Scott|first=Graham|last=Scott|publisher=Oxford University Press|year=2010 |isbn=978-0-19-856997-8|location=}}
* {{cite book|last=Sibley |first=David|title=The Sibley Guide to Bird Life & Behaviour|year=2001|publisher=Christopher Helm|location=London |isbn=978-0-7136-6250-4|ref={{harvid|Sibley, et al.|2001}}|display-authors=0|url=https://books.google.com/books?id=_wwhHAAACAAJ}}
* {{cite book|last=Terres|first=J. K.|title=The Audubon Society Encyclopedia of North American Birds|publisher=Knopf|year=1980|location=New York, NY|isbn=978-0-394-46651-4|url=https://archive.org/details/audubonsocietyen00terr}}
* {{cite web|last=Trail|first=Pepper|year=2001|title=Wing Feathers|publisher=U.S. Fish and Wildlife Service|url=https://www.fws.gov/lab/idnotes/WingFeathers-prnt.pdf|access-date=August 5, 2017|archive-date=September 30, 2017|archive-url=https://web.archive.org/web/20170930001526/https://www.fws.gov/lab/idnotes/WingFeathers-prnt.pdf|url-status=dead}}
* {{cite book|last=Vinicombe|first=Keith |title=The Helm Guide to Bird Identification|url=https://books.google.com/books?id=9eHzAgAAQBAJ&pg=PA14|year=2014|publisher=Bloomsbury Publishing|isbn=978-1-4729-0554-3|location=London}}
* {{cite book|last=Weaver|first=Peter|title=The Birdwatcher's Dictionary|url=https://books.google.com/books?id=qx64F8iwnJkC|year=1981|publisher=Bloomsbury Publishing|isbn=978-1-4081-3852-6|location=London}}

{{Birds|state=collapsed}}

[[Category:Birds]]
[[Category:Bird anatomy|*]]
[[Category:Glossaries of zoology|Bird]]

{{Sourceattribution|Glossary of bird terms}}