Cowbird

Cowbirds are birds belonging to the genus Molothrus in the family Icteridae. They are of New World origin. They are brood parasites, laying their eggs in the nests of other species. The genus Molothrus contains: The non-brood parasitic baywing was formerly placed in this genus; it is now classified as Agelaioides badius. Cowbirds eat insects, including the large numbers that may be stirred up by cattle. The birds in this genus are infamous for laying their eggs in other birds' nests. The cowbird will watch for when its host lays eggs, and when the nest is left unattended, the female will come in and lay its own eggs. The female cowbird may continue to observe the nest after laying eggs. If the cowbird egg is removed, the female cowbird may destroy the host's eggs to dissuade further removals, according to the Mafia hypothesis. Widespread predatory behaviors in cowbirds could slow the evolution of rejection behaviors and further threaten populations of some of the >100 species of regular cowbird hosts.