The Brown-headed Cowbird
is a stocky blackbird with a fascinating approach to raising its young. Females
forgo building nests and instead put all their energy into producing eggs. Brown-headed
Cowbird females can lay 36 eggs in a season. These they lay in the nests of other
birds, abandoning their young to foster parents, usually at the expense of at
least some of the host’s own chicks.
The Brown-headed Cowbird eggs have been documented in nests of at least 220 host species, including hummingbirds and raptors. More than 140 different species of birds are known to have raised young cowbirds.
Historically, Brown-headed Cowbirds probably followed herds of bison, walking behind them to take advantage of food kicked up in the bison's wake. Now they follow cattle and other large grazers in much the same way. They almost always forage on the ground, but also lurk about in trees and bushes, mostly watching quietly for nests to parasitize.
The Brown-headed Cowbird eggs have been documented in nests of at least 220 host species, including hummingbirds and raptors. More than 140 different species of birds are known to have raised young cowbirds.
Historically, Brown-headed Cowbirds probably followed herds of bison, walking behind them to take advantage of food kicked up in the bison's wake. Now they follow cattle and other large grazers in much the same way. They almost always forage on the ground, but also lurk about in trees and bushes, mostly watching quietly for nests to parasitize.
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Some bird eggs have visual signatures that help them distinguish they own clutch from impostor cuckoo eggs |
