Photo: Tom J. Ulrich/ Vireo

Shiny Cowbird

Molothrus bonariensis

Conservation status Impact of this parasite on North American birds remains to be seen. In Puerto Rico, has driven Yellow-shouldered Blackbird to endangered status.
Family Blackbirds and Orioles
Habitat Semi-open country. In North America, has been found mostly near the coast, often foraging on extensive lawns. In the tropics, found in any kind of open or semi-open terrain, mostly in the lowlands.
Originally native to South America, this little blackbird spread gradually through the West Indies in recent decades, island-hopping north through the Lesser Antilles and then west toward Cuba. It arrived in Florida in 1985, and has become locally common there, with some seen elsewhere in the Southeast. Like other cowbirds, this species is a parasite, so its arrival in our area was not welcomed by conservationists.
Photo Gallery
Feeding Behavior

Forages mostly by walking on the ground in open areas. Often forages in small flocks, and may associate with other kinds of cowbirds or other blackbirds. In the tropics, will feed in association with horses or cattle in pastures.


Eggs

Quite variable in color: may be unmarked white, or may have gray dots, large red spots, dark lines, brown blotches, or rarely can be all dark red. Number of eggs laid by a female in one season is unknown, but may be many. Female sometimes punctures eggs already in a nest before she lays her own. In South America, parasitizes nests of many species. May specialize in other areas: in Puerto Rico, mostly parasitizes Yellow-shouldered Blackbird. Young: Cowbird nestling is fed by "host" parents and develops rapidly, probably leaving nest after about 10-12 days.


Young

Cowbird nestling is fed by "host" parents and develops rapidly, probably leaving nest after about 10-12 days.

Diet

Mostly seeds and insects. Diet in North America has not been studied. In the tropics, feeds on insects and other arthropods, and many seeds.


Nesting

A brood parasite, never raising its own young. Early in breeding season, males sing to attract females. A male singing to a female on the ground may take off and fly in a wide circle around her with fluttering wingbeats. Nest: Builds no nest of its own; lays its eggs in nests of other birds.

Text © Kenn Kaufman, adapted from
Lives of North American Birds

Illustration © David Allen Sibley.
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Migration

Pattern of migration within North America still poorly known. In some recent years, numbers have been seen moving through southern Florida in spring, suggesting flocks arriving from Caribbean. Strays have dispersed as far as Texas, Oklahoma, and Maine.

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Migration

Pattern of migration within North America still poorly known. In some recent years, numbers have been seen moving through southern Florida in spring, suggesting flocks arriving from Caribbean. Strays have dispersed as far as Texas, Oklahoma, and Maine.

Songs and Calls
Song a melodious warble. A variety of harsh metallic call notes.

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