View source for Biology:White-eared titi

{{Short description|Species of New World monkey}}
{{Speciesbox
|name=White-eared titi
|status=LC
|status_system=IUCN3.1
|status_ref=<ref name=IUCN>{{Cite journal |author=Veiga, L. M. |author2=Wallace, R. B. |author3=Ferrari, S. F. |name-list-style=amp |title=''Plecturocebus donacophilus'' |journal=The IUCN Red List of Threatened Species |volume=2008 |page=e.T41548A10497668 |date=2008 |doi=10.2305/IUCN.UK.2008.RLTS.T41548A10497668.en}}</ref>
|image=White-eared titi (Callicebus donacophilus).jpg
|genus=Plecturocebus
|species=donacophilus
|authority=(d'Orbigny, 1836)
|range_map=White-eared Titi area.png
|range_map_caption=White-eared titi range
|synonyms=''Callicebus donacophilus'' <small>d'Orbigny, 1836</small>
}}

The '''white-eared titi''', '''''Plecturocebus donacophilus''''', also known as the '''Bolivian titi''' or '''Bolivian gray titi''', is a species of titi, a type of New World monkey, from eastern Bolivia and an area of western {{wipe|Brazil}}. The species has a range that extends east from the Manique River in Beni Department, Bolivia to southern Rondônia in Brazil. The southern end of its range includes forests around the city of Santa Cruz de la Sierra.

It is a medium-sized monkey with a grey back, orange underside and distinctive white ear tufts. It has an [[Biology:Omnivore|omnivorous]] diet, eating fruits, other plant materials and invertebrates. It is [[Earth:Predation|predated]] upon primarily by [[Biology:Bird of prey|raptors]], though [[Biology:Felidae|felid]]s and other monkey species have been known to attack the species. It is a [[Social:Monogamy|monogamous]] species and lives in small groups of two to seven members consisting of the pair and their offspring. The family group has a [[Earth:Home range|home range]] of {{Convert|0.5|to|14|ha|acre}} and the adults have a complex vocal repertoire to maintain their territory. It is also known for its characteristic twining of tails when groups are sitting together. White-eared titis can live for more than 25 years in captivity.

The white-eared titi population has a declining trend. The decline is believed to be mainly caused by human-induced [[Earth:Habitat destruction|habitat loss]] and degradation. Despite this, the [[Organization:International Union for Conservation of Nature|International Union for Conservation of Nature]] (IUCN) classified the species as being of least concern in 2008 as it has shown adaptability to habitat disturbance and is found over a wide range.

== Taxonomy ==
The white-eared titi belongs to the New World monkey family [[Biology:Pitheciidae|Pitheciidae]], which contains the titis, saki monkeys (''Pithecia''), bearded sakis (''Chiropotes''), and uakaris (''Cacajao''). It is a member of the subfamily Callicebinae. It was first described as ''Callicebus donacophilus'' in 1836,<ref name="MSW3">{{MSW3 Groves |pages=143 |id=12100329}}</ref><ref name="ITIS">{{ITIS |id=572965 |taxon=''Plecturocebus donacophilus'' |access-date=28 November 2006}}</ref><ref name="vanRoosmalen_etal2002">{{Cite journal |last1=van Roosmalen |first1=M. G. M. |last2=van Roosmalen |first2=T. |last3=Mittermeier |first3=R. A. |date=June 2002 |title=A taxonomic review of the titi monkeys, genus ''Callicebus'' Thomas, 1903, with the description of two new species, ''Callicebus bernhardi'' and ''Callicebus stephennashi'', from Brazilian Amazonia |journal=Neotropical Primates |volume=10 |pages=1–52 |issue=Suppl|citeseerx=10.1.1.177.4220 |url=http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.177.4220&rep=rep1&type=pdf |type=pdf}}</ref> but was reassessed based on molecular evidence and recombined as a species within the genus ''[[Biology:Plecturocebus|Plecturocebus]]''.<ref name="Byrne2016">{{Cite journal |last1=Byrne |first1=H. |last2=Rylands |first2=A. B. |last3=Carneiro |first3=J. C. |last4=Alfaro |first4=J. W. L. |last5=Bertuol |first5=F. |last6=da Silva |first6=M. N. F. |last7=Messias |first7=M. |last8=Groves |first8=C. P. |author8-link=Colin Groves |last9=Mittermeier |first9=R. A. |author9-link=Russell Mittermeier |date=2016 |title=Phylogenetic relationships of the New World titi monkeys (''Callicebus''): first appraisal of taxonomy based on molecular evidence |journal=Frontiers in Zoology |volume=13 |pages=10 |doi=10.1186/s12983-016-0142-4 |issn=1742-9994 |pmc=4774130 |pmid=26937245}}</ref>

Within the new genus ''Plecturocebus'', the white-eared titi is part of the ''P. donacophilus'' group with the Rio Beni titi (''P. modestus''), Rio Mayo titi (''P. oenanthe''), [[Biology:Olalla brothers' titi|Olalla brothers' titi]] (''P. olallae''), [[Biology:White-coated titi|white-coated titi]] (''P. pallescens''), and [[Biology:Urubamba brown titi|Urubamba brown titi]], (''P. urubambensis'').<ref name="Byrne2016" /><ref name="vanRoosmalen_etal2002" /> The white-coated titi has sometimes been considered a [[Biology:Subspecies|subspecies]] of the white-eared titi,<ref name="Hershkovitz1990">{{Cite journal |last=Hershkovitz |first=P. |year=1990 |title=Titis, New World monkeys of the genus ''Callicebus'' (Cebidae, Platyrrhini): a preliminary taxonomic review |journal=Fieldiana Zoology |volume=55 |pages=1–109 |doi=10.5962/bhl.title.2843 |doi-access=free}}</ref> but they are treated as separate species in the latest edition of Mammal Species of the World.<ref name="MSW3" />

== Physical description ==
The white-eared titi is a medium-sized primate with grey to orange [[Biology:Fur|pelage]]. The species does not exhibit [[Biology:Sexual dimorphism|sexual dimorphism]]; the male's head and body length averages {{Convert|311|mm|in}} while females average {{Convert|340|mm|in}}.<ref name=Hershkovitz1990 /> The white-eared titi's fluffy tail is longer than the length of its head and body together.<ref name=Hershkovitz1990 /> It typically has thick fur, with a dorsal side and limbs that vary in colour from grey agouti to orange agouti, with an orange underside and white ear tufts.<ref name="Gron2007a">{{Cite web |last=Gron |first=K. J. |date=19 December 2007 |title=Primate factsheets: dusky titi (''Callicebus moloch'') taxonomy, morphology, & ecology |url=http://pin.primate.wisc.edu/factsheets/entry/dusky_titi/taxon |publisher=Primate Info Net |access-date=10 April 2010}}</ref>

Body weight ranges from around {{Convert|800|to|1200|g|lb}}, with the female generally a little lighter.<ref name="Gron2007a" /> It has the dental formula {{DentalFormula|upper=2.1.3.3|lower=2.1.3.3|total=36}}, meaning that on each side of the jaw it has two incisors, one [[Biology:Canine tooth|canine tooth]], three premolars, and three molar teeth.<ref name="AnkelSimons2000">{{Cite book |title=Primate anatomy |first=F. |last=Ankel-Simons |publisher=Academic Press |year=2000 |isbn=9780120586707}}</ref> The canine teeth are relatively short when compared with other New World monkeys.<ref name="Fleagle1998">{{Cite book |title=Primate adaption and evolution |edition=Second |last=Fleagle |first=J. |pages=[https://archive.org/details/primateadaptatio0000flea/page/145 145–147] |year=1998 |publisher=Academic Press |isbn=978-0122603419 |url=https://archive.org/details/primateadaptatio0000flea/page/145}}</ref> In captivity, the white-eared titi has been known to live for over 25 years.<ref name="Weigl2005">{{Cite book |last=Weigl |first=R. |year=2005 |title=Longevity of mammals in captivity; from the living collections of the world |location=Stuttgart |publisher=E. Schweizerbartsche |pages=54| isbn=9783510613793}}</ref>

== Behaviour ==
The white-eared titi is [[Biology:Crypsis|cryptic]], [[Biology:Diurnality|diurnal]] and known to live in small family groups.<ref name="Kinzey1981" /><ref name="EisenbergRedford1999">{{Cite book |last1=Eisenberg |first1=J. F |last2=Redford |first2=K. H. |year=1999 |title=Mammals of the Neotropics, volume 3: Ecuador, Bolivia, Brazil |publisher=University of Chicago Press |location=Chicago |isbn=9780226195421}}</ref> It is a [[Social:Monogamy|monogamous]] species that is thought to mate for life and lives in groups that usually consist of two to seven members; an adult pair and up to five young.<ref name="Wright1984">{{Cite book |last=Wright |first=P. C. |year=1984 |chapter=Ecological correlates of monogamy in ''Aotus'' and ''Callicebus'' |editor1=Else, J. G. |editor2=Lee, P. C. |title=Primate ecology and conservation |location=Cambridge |publisher=Cambridge University Press |pages=159–167}}</ref><ref name="MasonMendoza1993">{{Cite journal |last1=Mason |first1=W. A. |last2=Mendoza |first2=S. P. |year=1993 |title=Contrasting life modes in cebidae: titi monkeys (''Callicebus'') and squirrel monkeys (''Saimiri'') |publisher=AAZPA Regional Conference Proceedings |pages=715–722}}</ref><ref name="Kinzey1997">{{Cite book |last=Kinzey |first=W. G. |year=1997 |chapter=Synopsis of the New World primates: ''Callicebus'' |editor=Kinzey, W. G. |title=New World primates: ecology, evolution, and behavior |location=New York |publisher=Aldine De Gruyter |pages=213–221}}</ref><ref name="Bossuyt2002">{{Cite journal |last=Bossuyt |first=F. |year=2002 |title=Natal dispersal of titi monkeys (''Callicebus moloch'') at Cocha Cashu, Manu national park, Peru |publisher=American Journal of Physical Anthropology |volume=34 |pages=47}}</ref> Multi-male groups have also been recorded.<ref name="Bicca-Marques_etal2002">{{Cite journal |last1=Bicca-Marques |first1=J. C. |last2=Garber |first2=P. A. |last3=Azevedo-Lopes |first3=M. A. O. |year=2002 |title=Evidence of three resident adult male group members in a species of monogamous primate, the red titi monkey (''Callicebus cupreus'') |journal=Mammalia |volume=66 |issue=1 |pages=138–142}}</ref> Offspring are carried by the male, and are always with them, except when [[Social:Breastfeeding|feeding]].<ref name="Mason1966" /> Between the ages of two to four years, offspring will disperse from the natal group, with females leaving earlier than the males.<ref name="Bossuyt2002" /><ref name="Wright1985">{{Cite journal |last=Wright |first=P. C. |year=1985 |title=The costs and benefits of nocturnality for ''Aotus trivirgatus'' (the night monkey) |volume=PhD dissertation |publisher=City University of New York |pages=315}}</ref>

[[File:Callicebus-donacophilus 09.jpg|thumb|left|Young are carried during their first few months.]]

There is a strong bond between the adult mating pair, they stay close and carry out activities together.<ref name="Mason1966">{{Cite journal |last=Mason |first=W. A. |year=1966 |title=Social organization of the South American monkey, ''Callicebus moloch'': a preliminary report |journal=Tulane Studies in Zoology and Botany |volume=13 |pages=23–28 |url=https://archive.org/stream/cbarchive_49279_socialorganizationofthesoutham9999/socialorganizationofthesoutham9999#page/n1/mode/2up}}</ref><ref name="CubicciottiMason1978">{{Cite journal |last1=Cubicciotti |first1=D. D. |last2=Mason |first2=W. A. |year=1978 |title=Comparative studies of social behavior in ''Callicebus'' and ''Saimiri'': heterosexual jealousy behavior |journal=Behavioral Ecology and Sociobiology |volume=3 |issue=3 |pages=311–322 |doi=10.1007/BF00296316|s2cid=29148310 }}</ref><ref name="Anzenberger_etal1986">{{Cite journal |last1=Anzenberger |first1=G. |last2=Mendoza |first2=S. P. |last3=Mason |first3=W. A. |year=1986 |title=Comparative studies of social behavior in ''Callicebus'' and ''Saimiri'': behavioral and physiological responses of established pairs to unfamiliar pairs |journal=American Journal of Primatology |volume=11 |issue=1 |pages=37–51 |doi=10.1002/ajp.1350110105|pmid=31979464 |s2cid=86729566 }}</ref><ref name="Mendoza_etal2002">{{Cite journal |last1=Mendoza |first1=S. P. |last2=Reeder |first2=D. M. |last3=Mason |first3=W. A. |year=2002 |title=Nature of proximate mechanisms underlying primate social systems: simplicity and redundancy |journal=Evolutionary Anthropology |volume=11 |issue=1 |pages=112–116 |doi=10.1002/evan.10071 |citeseerx=10.1.1.571.792|s2cid=29705787 }}</ref> Either member of the pair may follow the other and leadership changes through the day. Evidence of the strength of the pair bond is shown by grooming, huddling together with their tails twined, nuzzling, and gentle grasping.<ref name="Mason1966" /> Titi monkeys are highly territorial<ref name="Ferrari_etal2000" /> and when confronted with another family group, both will respond with threatening behaviour, males showing increased agitation towards intruding males.<ref name="Anzenberger_etal1986" /><ref name="MendozaMason1986" /><ref name="Mason1968">{{Cite book |last=Mason |first=W. A. |year=1968 |chapter=Use of space by ''Callicebus'' |editor=Jay, P. C. |title=Primates: studies in adaptation and variability |location=New York |publisher=Holt, Rinehart and Winston |pages=200–216}}</ref><ref name="Fernandez-Duque_etal1997">{{Cite journal |last1=Fernandez-Duque |first1=E. |last2=Mason |first2=W. A. |last3=Mendoza |first3=S. P. |year=1997 |title=Effects of duration of separation on responses to mates and strangers in the monogamous titi monkey (''Callicebus moloch'') |journal=American Journal of Primatology |volume=43 |issue=3 |pages=225–237 |pmid=9359966 |doi=10.1002/(SICI)1098-2345(1997)43:3<225::AID-AJP3>3.0.CO;2-Z|s2cid=11433257 }}</ref> When not close together, the pair show a significant amount of distress and agitation.<ref name="MendozaMason1986">{{Cite journal |last1=Mendoza |first1=S. P. |last2=Mason |first2=W. A. |year=1986 |title=Contrasting responses to intruders and to involuntary separation by monogamous and polygynous New World monkeys |journal=Physiological Behavior |volume=38 |issue=6 |pages=795–801 |doi=10.1016/0031-9384(86)90045-4 |pmid=3823197|s2cid=26077383 }}</ref>

Titi monkeys are well known for their vocal communication, and have a complex repertoire of calls. The calls can be divided into two categories: high-pitched quiet calls and low-pitched loud calls.<ref name="Robinson1977">{{Cite journal |last=Robinson |first=J. G. |year=1977 |title=Vocal regulation of spacing in the titi monkey (''Callicebus moloch'') |volume=PhD dissertation |publisher=University of North Carolina-Chapel Hill}}</ref><ref name="Robinson1979">{{Cite journal |last=Robinson |first=J. G. |year=1979 |title=An analysis of the organization of vocal communication in the titi monkey ''Callicebus moloch'' |journal=Zeitschrift für Tierzuchtung und Zuchtungsbiologie |volume=49 |issue=4 |pages=381–405|doi=10.1111/j.1439-0310.1979.tb00300.x |pmid=115173 }}</ref> Vocalisations are often combined and repeated to form sequences that are used to indicate distress, conflict, play, bonding, disturbance, and to strengthen territory.<ref name="Gron2007b" /> The high-pitched quiet calls are mostly used when the monkeys are disturbed, but may also be used before or after group calling, while foraging, or to find other members of the group.<ref name="Robinson1977" /><ref name="Moynihan1966">{{Cite journal |last=Moynihan |first=M. |year=1966 |title=Communication in the titi monkey, ''Callicebus'' |journal=Journal of Zoology |volume=150 |pages=77–127 |doi=10.1111/j.1469-7998.1966.tb02999.x}}</ref> The loud low-pitched calls are mostly used in long distance group calling. Their function is to ensure adequate spacing between the home ranges of different family groups.<ref name="Gron2007b">{{Cite web |last=Gron |first=K. J. |date=19 December 2007 |title=Primate factsheets: dusky titi (''Callicebus moloch'') behaviour |url=http://pin.primate.wisc.edu/factsheets/entry/dusky_titi/behav |publisher=Primate Info Net |access-date=10 April 2010}}</ref> These vocalisations are known as duets, and generally involve the male and female. If a neighbouring group is within earshot of these calls they will respond with their own duetting.<ref name="Robinson1977" />

[[File:White-eared titi (Callicebus donacophilus) duetting.jpg|thumb|upright|The white-eared titi has a complex vocal repertoire.]]

The white-eared titi is arboreal, spending most of its time in the lower strata of the forest.<ref name="Ferrari_etal2000" /> It may enter the main [[Biology:Canopy|canopy]] when travelling longer distances<ref name="Lawler_etal2006" /><ref name="Youlatos1999" /> and may also cross small areas of open ground, though the latter is rare.<ref name="Kinzey1981">{{Cite book |last=Kinzey |first=W. G. |year=1981 |chapter=The titi monkeys, genus ''Callicebus'': I. description of the species |editor1=Coimbra-Filho, A. F. |editor2=Mittermeier, R. A. |title=Ecology and behavior of Neotropical primates Volume 1 |location=Rio de Janeiro |publisher=Academia Brasileira de Ciências |pages=241–276}}</ref><ref name="Fragaszy1979">{{Cite book |last=Fragaszy |first=D. M. |chapter=Titi and squirrel monkeys in a novel environment |year=1979 |editor1=Erwin, J. |editor2=Maple, T. L. |editor3=Mitchell, G. |title=Captivity and behavior: primates in breeding colonies, laboratories, and zoos |location=New York |publisher=Van Nostrand Reinhold |pages=172–216 |isbn=9780442223298}}</ref> During normal movement through its environment it is [[Quadrupedalism|quadrupedal]] and mostly walks, clambers and leaps, but it can also bound and climb.<ref name="Youlatos1999" /> It leaps small distances, no more than a few body lengths, between trees where vegetation is not thick enough to support its primary forms of locomotion.<ref name="Lawler_etal2006">{{Cite journal |last1=Lawler |first1=R. R. |last2=Ford |first2=S. M. |last3=Wright |first3=P. C. |last4=Easley |first4=S. P. |year=2006 |title=The locomotor behavior of ''Callicebus brunneus'' and ''Callicebus torquatus'' |journal=Folia Primatologica |volume=77 |issue=3 |pages=228–239 |doi=10.1159/000091232 |pmid=16612097|s2cid=6892953 }}</ref> When travelling on the ground it is said to use a "bounding movement"<ref name="Gron2007a" /> whereby it leaps more than {{Convert|1|m|ft}} off the ground.<ref name="Kinzey1981" /><ref name="Fragaszy1979" /> The titi monkey prefers branches which are less than {{Convert|5|cm|in}} in diameter and its tail never touches the support it is on.<ref name="Youlatos1999">{{Cite journal |author=Youlatos, D. |year=1999 |title=Comparative locomotion of six sympatric primates in Ecuador |journal=Annales des Sciences Naturelles |volume=20 |issue=4 |pages=161–168 |doi=10.1016/s0003-4339(00)88884-x}}</ref><ref name="Welker_etal1998">{{Cite journal |last1=Welker |first1=C. |last2=Jantschke |first2=B. |last3=Klaiber-Schuh |first3=A. |year=1998 |title=Behavioural data on the titi monkey ''Callicebus cupreus'' and the owl monkey ''Aotus azarae boliviensis''. A contribution to the discussion on the correct systematic classification of these species. Part I: introduction and behavioural differences |journal=Primate Report |volume=51 |pages=3–18}}</ref>

== Ecology ==
There is relatively little known about the ecology of the white-eared titi or even titi monkeys in general,<ref name="Ferrari_etal2000" /> and few studies have focused on the white-eared titi. It is diurnal, commencing activity around sunrise and continuing until sunset.<ref name="Mason1968" /><ref name="Kinzey1978">{{Cite book |last=Kinzey |first=W. G. |year=1978 |chapter=Feeding behaviour and molar features in two species of titi monkey |editor1=Chivers, D. J. |editor2=Herbert, J. |title=Recent advances in primatology |volume=1: Behaviour |location=London |publisher=Academic Press |pages=373–385}}</ref><ref name="Wright1989">{{Cite journal |last=Wright |first=P. C. |year=1989 |title=The nocturnal primate niche in the new world |journal=Journal of Human Evolution |volume=18 |issue=7 |pages=635–658 |doi=10.1016/0047-2484(89)90098-5}}</ref> Food availability may influence activity times; if there is an abundance of food in the warmer months when plants are fruiting titi monkeys may start earlier, or if there is a lack of food, titi monkeys may remain at the feeding tree into the evening.<ref name="Wright1989" /> The titi monkey usually rests during the middle of the day and has two main feeding periods, in the morning and in the afternoon. It has an increased period of feeding towards the end of the day. In total, the titi monkey is active for an average of 11.5 hours, 2.7 hours of which is spent feeding.<ref name="Kinzey1978" /> Titi monkeys sleep on branches at least {{Convert|15|m|ft}} above the ground. In the same manner as resting during the day, titi monkeys huddle together and twine tails to sleep.<ref name="Kinzey1997" /><ref name="Mason1968" /><ref name="Robinson1979b">{{Cite journal |last=Robinson |first=J. G. |year=1979 |title=Vocal regulation of use of space by groups of titi monkeys ''Callicebus moloch'' |journal=Behavioral Ecology and Sociobiology |volume=5 |pages=1–15 |doi=10.1007/bf00302691|s2cid=30990441 }}</ref>

[[File:White-eared titi (Callicebus donacophilus) group.jpg|thumb|left|When resting as a group white-eared titis often twine tails together.]]

Though there is little published research on the diet of the white-eared titi, titi monkeys in general are [[Biology:Omnivore|omnivore]]s that eat fruit, leaves, insects, and seeds.<ref name="IUCN" /><ref name="Wright1989" /><ref name="IzawaYoneda1981">{{Cite journal |last1=Izawa |first1=K. |last2=Yoneda |first2=M. |year=1981 |title=Habitat utilization of nonhuman primates in a forest of the western pando, Bolivia |journal=Kyoto University Overseas Research Reports of New World Monkeys |volume=2 |pages=13–22}}</ref> They mostly eat leaves, especially protein-rich young leaves and leaf buds,<ref name="Terborgh1985">{{Cite book |last=Terborgh |first=J. |year=1985 |chapter=The ecology of Amazonian primates |editor1=Prance, G. T. |editor2=Lovejoy, T. E. |title=Key environments: Amazonia |location=Oxford |publisher=Pergamon Press |pages=284–304}}</ref><ref name="Crandlemire-Sacco1988">{{Cite journal |last=Crandlemire-Sacco |first=J. |year=1988 |title=An ecological comparison of two sympatric primates: ''Saguinus fuscicollis'' and ''Callicebus moloch'' of Amazonian Peru |journal=Primates |volume=29 |issue=4 |pages=465–475 |doi=10.1007/bf02381134|s2cid=22332355 }}</ref> so a significant period of the day is spent resting to digest the [[Chemistry:Cellulose|cellulose]].<ref name="Wright1989" /> They consume more than 100 different species of plants and fruit.<ref name="Wright1985" /> Titi monkeys will also eat small insects (ants, moths, butterflies, and their cocoons), spiders, and can catch flying prey if it comes close to them.<ref name="Wright1985" /><ref name="Wright1989" /><ref name="Crandlemire-Sacco1988" /><ref name="Meritt1980">{{Cite journal |last=Meritt Jr. |first=D. A. |year=1980 |title=Captive reproduction and husbandry of the douroucouli ''Aotus trivirgatus'' and the titi monkey ''Callicebus'' spp. |journal=International Zoo Yearbook |volume=20 |pages=52–59 |doi=10.1111/j.1748-1090.1980.tb00942.x}}</ref> During the dry season there is an increased feeding time on leaves,<ref name="Wright1989" /><ref name="Lawrence2007">{{Cite journal |last=Lawrence |first=J. M. |year=2007 |title=Understanding the pair bond in brown titi monkeys (''Callicebus brunneus''): male and female reproductive interests |volume=PhD dissertation |publisher=Columbia University}}</ref> and during lactation it is thought insect consumption increases to augment the protein content of the diet.<ref name="HerreraHeymann2004">{{Cite journal |last1=Tirado Herrera |first1=E. R. |last2=Heymann |first2=E. W. |year=2004 |title=Does mom need more protein? Preliminary observations on differences in diet composition in a pair of red titi monkeys, ''Callicebus cupreus'' |journal=Folia Primatologica |volume=75 |issue=3 |pages=150–153 |doi=10.1159/000078304 |pmid=15240979|s2cid=40269938 }}</ref>

The titi monkey may travel between {{Convert|425|and|1152|m|ft|abbr=on}} during the day, and can maintain a [[Earth:Home range|home range]] of {{Convert|0.005|to|0.14|km2|sqmi|abbr=on}}. During the dry season there is less fruit available and therefore less need to travel large distances, so the day range may only be a third of the usual distance.<ref name="Gron2007a" /> Its home range is often shared with other primate species including [[Biology:Marmoset|marmoset]]s, squirrel monkeys, [[Biology:Capuchin monkey|capuchins]], owl monkeys, howler monkeys, and [[Biology:Spider monkey|spider monkey]]s.<ref name="Gron2007a" /><ref name="Youlatos1999" /> It is sometimes chased from feeding sites by larger species,<ref name="Wright1996">{{Cite book |last=Wright |first=P. C. |year=1996 |chapter=The Neotropical primate adaption to nocturnality: feeding in the night (''Aotus nigriceps'' and ''A. azarae'') |editor1=Norconk, M. A. |editor2=Rosenberer, A. L. |editor3=Garber, P. A. |title=Adaptive radiations of neotropical primates |location=New York |publisher=Plenum Press |pages=369–382}}</ref> and will generally try to avoid other primates.<ref name="Wright1985" />
{{Clear}}

=== Habitat and distribution ===
The white-eared titi is found in tropical humid forests, preferring drier regions to more humid ones.<ref name="IUCN" /> It is found in [[Earth:Riparian zone|riparian zone]]s and [[Biology:Gallery forest|gallery forest]]s and is clearly associated with open habitats like [[Earth:Grassland|grassland]]s and swampy grasslands.<ref name="Ferrari_etal2000">{{Cite journal |last1=Ferrari |first1=S. |first2=S. |last2=Iwanga |first3=M. |last3=Messias |first4=E. |last4=Ramos |first5=P. |last5=Ramos |first6=E. |last6=da Cruz Neto |first7=P. |last7=Coutinho |year=2000 |title=Titi monkeys (''Callicebus'' spp., Atelidae: Platyrrhini) in the Brazilian state of Rondônia |journal=Primates |volume=41 |issue=2 |pages=229–234 |doi=10.1007/BF02557805|s2cid=33425235 }}</ref> It is found in areas with dense vegetation, often choosing to inhabit the thickest parts of the forest.<ref name="vanRoosmalen_etal2002" /> The species seems to be quite tolerant of habitat disturbance.<ref name="IUCN" /><ref name="Ferrari_etal2000" /> In Bolivia, the white-eared titi is found in the upper parts of the Mamoré, Grande, and San Miguel river basins, east of the Manique River in Beni and in the forests surrounding the city of Santa Cruz de la Sierra.<ref name="vanRoosmalen_etal2002" /><ref name=IUCN/> Its range extends north to southern Rondônia in Brazil.<ref name="IUCN" /><ref name="Ferrari_etal2000"/><ref>{{cite book |editor-last1=Veiga |editor-first1=L. M. |editor-first2=A. A. |editor-last2=Barnett |editor-first3=M. A. |editor-last3=Norconk |date=2013 |title=Evolutionary biology and conservation of titis, sakis and uacaris |pages=32–33, 328, 337, 373 |publisher=Cambridge University Press |isbn=978-0-521-88158-6}}</ref><ref name="Hershkovitz1990"/>

== Conservation status ==
The white-eared titi is considered to be of least concern on the [[Organization:International Union for Conservation of Nature|International Union for Conservation of Nature]] (IUCN) [[Organization:IUCN Red List|Red List]]. The species is not considered threatened due to its adaptability and abundance over a relatively wide range, and despite having a decreasing population trend the decline is not rapid enough to be placed in a threatened category. The species is also listed on [[Biology:CITES#Appendix II|CITES Appendix II]].<ref name="IUCN" />

The white-eared titi's main threat is deforestation and habitat loss due to agriculture. The area of greatest habitat loss is around the city of Santa Cruz de la Sierra, but it still survives within the city limits and on the edges of many rural establishments. It has few natural predators and is proven to be adaptable to habitat disturbance.<ref name="IUCN" /> Farmland may surround and isolate areas of titi habitat which occasionally has positive benefits to the monkey. Farmers may prevent hunters on the land, thereby inadvertently protecting the species. It also appears that the titi monkey can cross open ground between forest fragments,<ref name="Felton_etal2006">{{Cite journal |last1=Felton |first1=A. |last2=Felton |first2=A. M. |last3=Wallace |first3=R. B. |last4=Gómez |first4=H. |year=2006 |title=Identification, behavioral observations, and notes on the distribution of the titi monkeys ''Callicebus modestus'' Lönnberg, 1939 and ''Callicebus olallae'', Lönnberg 1939 |journal=Primate Conservation |volume=20 |pages=41–46 |doi=10.1896/0898-6207.20.1.41|s2cid=86779155 }}</ref> and some groups can thrive in disturbed habitats near human activities.<ref name="vanRoosmalen_etal2002" /> However, the fragmented habitats may prevent the establishment of new territories and decrease reproductive opportunities.<ref name="DeLuycker2006">{{Cite journal |last=DeLuycker |first=A. M. |year=2006 |title=Preliminary report and conservation status of the Río Mayo titi monkey, ''Callicebus oenanthe'' Thomas, 1924, in the Alto Mayo valley, northeastern Peru |journal=Primate Conservation |volume=21 |pages=33–39 |doi=10.1896/0898-6207.21.1.33|s2cid=86430327 }}</ref> Forest corridors to connect fragmented forests have been proposed as an effective means to help ensure the survival of the titi monkey.<ref name="DeLuycker2006" /> The white-eared titi is found in the Beni Biological Station Biosphere Reserve and the Amboro National Park in Bolivia and benefits from the protection these reserves provide.<ref name="IUCN" />

== References ==
{{Reflist}}

{{Taxonbar|from1=Q56120524|from2=Q581519}}

[[Category:Plecturocebus|white-eared titi]]

{{Sourceattribution|White-eared titi|1}}