The Brown-headed Cowbird does not build a nest of its own. The female lays her eggs in
the nests of other bird species. The host parents then raise the cowbird chick as their
own. The cowbird's egg usually hatches a day or two before the host's eggs. Rapid growth
allows the cowbird chick to out compete the host's chicks for food and space in the nest.
The result is that the host's chicks usually perish. Female cowbirds have a long
reproductive period and can lay as many as 80 eggs over a two month period.
The Bird Banding Lab web site reports that between 1955 to 1997, a total of 834,539 Brown-headed Cowbirds were banded. Of these,
14,148 have been recovered, a recovery rate of 1.69%.
Banding studies show that Brown-headed Cowbirds are short distance migrants that winter
in the southern U. S. and Mexico. They may live up to 13 years in the wild. If you should
recover a banded bird, report the band number to the Bird Banding Lab by calling
Populations of Brown-headed Cowbirds are increasing at an alarming rate in
many regions. Because they are brood parasites, they are a particular threat to
populations of many other species of birds, especially endangered species such as
Kirtland's Warbler. Arguably, reduction of Brown-headed Cowbird populations would be of
benefit to many other songbird and gamebird species.
Back to Top | Back to Bird
All images are courtesy of CWBO. All image copyrights are owned by CWBO.
Any use of these images must have permission of CWBO.