Cowbird

Cowbirds are birds belonging to the genus Molothrus in the family Icteridae. They are of New World origin, but some species not native to North America are invasive there, 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.<ref>Template:Cite book The title page bears the year 1831 but the volume did not appear until 1832.</ref><ref>Template:Cite book</ref> The genus name combines the Ancient Greek Template:Transliteration, meaning "struggle" or "battle", with Template:Transliteration, meaning "to sire" or "to impregnate".<ref>Template:Cite book</ref> The English name "cowbird", first recorded in 1839, refers to this species often being seen near cattle.<ref name=OED>Template:Cite OED</ref>

Species

The genus contains six species:<ref name=IOC>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Template:Species table

One extinct species, 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.<ref>Template:Cite journal</ref> The convex-billed cowbird (Pandanaris convexa) is another extinct species that likely co-evolved with the megafauna, though it is placed in its own genus.

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

Behavior

Cowbirds eat mostly insects and seeds. Some species follow ungulates to catch insects stirred up by the larger animals' grazing.

Cowbirds reproduce by laying their eggs in other birds' nests. Female cowbirds observe a potential host bird laying 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 female cowbirds has been observed to attack and destroy the remaining eggs of such birds in retaliation, as suggested by the Mafia hypothesis.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Further reading

• Jaramillo and Burke, New World Blackbirds Template:ISBN

External links

• Audubon Society: Cowbirds and Conservation