lay their eggs in songbird nests and sometimes push the other eggs out.
Further information on the host relations of the parasitic cowbirds
Second, the Service initiated a brown-headed cowbird
control program to remove cowbirds
from active warbler nesting areas, reducing the threat of nest parasitism.
Effects of brown-headed cowbirds
and predators on the nesting success of yellow warblers in southwest Colorado.
In previous studies, numerous avian species like European starlings (Sturnus vulgaris), house sparrows (Passer domesticus), feral pigeons (Columba livia), red- winged blackbirds (Agelaius phoeniceus), common grackles (Quiscalus quiscula), brown headed cowbirds
(Molothrus ater), American kestrels (Falco sparverius), Canada geese (Branta canadensis), mallards (Anas platyrhynchos), cedar waxwings (Bomby cillacedrorum) and yellow-headed blackbirds (Xanthocephalus xanthocephalus) also showed the similar results and suppress the depredations when seeds treated with anthraquinone and methylanthranilate were provided to the birds (Cummings et al.
It should be noted that the case of the starlings and the cowbirds
Naturalists have ventured that cowbirds
adapted to this nomadic existence by becoming brood parasites and depositing their eggs in nests built and incubated by birds of other species.
Later researchers dismissed the idea, questioning whether the young cowbirds
could even grasp and yank off the parasites.
With the Alpena Bird Society near bankruptcy as it stumbles into its Centennial year, and its members interested only in gawking at birds, Hospitality Queen Karen decides that the senseless killing of cowbirds
in Joss Canyon, Alpena's last remaining wild land, must stop.
While other studies in the central United States have reported relatively high abundances of brown-headed cowbirds
(Cully and Winter 2000, Powell 2008, Rahmig et al.
There are at least two pairs of cardinals and their offspring among the regulars, along with yellow and purple finches (they turn brown for winter) as well as a rose-breasted grosbeak, red-bellied and downy woodpeckers, cowbirds
, grackles, robins and blue jays.
The birds are shown up-close in flight and interacting with other animals down below: barnacle geese fighting off polar bears that are invading their nests, pelicans plunging into huge shoals of sardine and anchovies and cowbirds
shadowing bison herds to feed on the insects disturbed by their hooves.
Although rates of brood parasitism by brown-headed cowbirds
(Molothrus ater) are high in some warbler species (Ortega, 1998), there are relatively few published accounts with yellow-throated warblers as the host.
Like modern cowbirds
, this species probably fed on seeds and insects large mammals exposed, Oswald said.
Abnormalities among brown-headed cowbirds
trapped in Alabama.