Biology:Cowbird

Short description: Genus of birds

Cowbird
Female brown-headed cowbird
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Passeriformes
Family:	Icteridae
Genus:	Molothrus Swainson, 1832
Type species
Fringilla pecoris Gmelin, JF, 1789
Species
M. rufoaxillaris M. oryzivorus M. bonariensis M. aeneus M. armenti M. ater

Cowbirds are birds belonging to the genus Molothrus in the family Icteridae. They are of New World origin, and are obligate brood parasites, laying their eggs in the nests of other species.

The genus was introduced by English naturalist William Swainson in 1832 with the brown-headed cowbird (Molothrus ater) as the type species. The genus name combines the Ancient Greek mōlos, meaning "struggle" or "battle", with thrōskō, meaning "to sire" or "to impregnate".

Species

The genus contains six species:

Image	Scientific name	Common name	Distribution
	Molothrus rufoaxillaris	Screaming cowbird	Northeast and central Argentina, southeast Bolivia, central Brazil and throughout Paraguay and Uruguay
	Molothrus oryzivorus (formerly in Scaphidura)	Giant cowbird	Southern Mexico south to northern Argentina, and on Trinidad and Tobago
	Molothrus bonariensis	Shiny cowbird	South America, the Caribbean, and Florida
	Molothrus aeneus	Bronzed cowbird	Southern U.S. states of California, Arizona, New Mexico, Texas, and Louisiana south through Central America to Panama
	Molothrus armenti	Bronze-brown cowbird	Colombia
	Molothrus ater	Brown-headed cowbird	Southern Canada, United States, and Mexico

One extinct species, the Talara cowbird (Molothrus resinosus), is known from fossil remains recovered from the Talara Tar Seeps of northwestern Peru, and likely went extinct during the late Quaternary. It may have been a close associate of Pleistocene megafauna communities, and may have gone extinct following their collapse in populations.

The nonparasitic baywings were formerly placed in this genus; they are now classified as Agelaioides.

Behavior

Cowbirds are insectivores.

The birds in this genus are infamous for laying their eggs in other birds' nests. The female cowbird notes when a potential host bird lays its eggs, and when the nest is left momentarily unattended, the cowbird lays its own egg in it. The female cowbird may continue to observe this nest after laying eggs. Some bird species have evolved the ability to detect such parasitic eggs, and may reject them by pushing them out of their nests, but the female cowbird has been observed to attack and destroy the remaining eggs of such birds as a consequence, dissuading further removals. Widespread predatory behaviors in cowbirds could slow the evolution of rejection behaviors and further threaten populations of some of the greater than 100 species of regular cowbird hosts, favoring host acceptance of parasitic eggs in a mafia-like contest between cowbirds and other species.

References

• Jaramillo and Burke, New World Blackbirds ISBN:0-7136-4333-1

External links

• Audubon Society: Cowbirds and Conservation

Wikidata ☰ Q1137414 entry