Brown-headed Cowbird, Molothrus ater


Brown-headed Cowbird
Above and below, adult male Brown-headed Cowbirds. The cowbirds, a genus of blackbirds, are brood parasites; they lay their eggs in the nests of birds of other species, which then raise their offspring to maturity. This sneakily exploitative behavior makes them unpopular among birders; most of us really can't quite keep ourselves from applying human moral notions to the natural behavior of wild creatures we love. See more further down the page...


Brown-headed Cowbird
A Brown-headed Cowbird pair, male above, female below, photographed in our back
yard in May 2008. Very likely this pair parasitized the nest of a Dark-eyed Junco in
our yard, which led to the scene of a small junco feeding a large cowbird shown in
two pictures further down the page. Juncos are common victims of cowbird brood
parasitism.

Brown-headed Cowbird


Brown-headed Cowbird
Another adult female Brown-headed Cowbird.

Brown-headed Cowbird
Above and below, a juvenile cowbird begging from, and being fed by, an adult junco at our back yard feeder in Summer 2008; the cowbird is probably the offspring of the pair shown further above. Note the much greater size of the cowbird; juncos don't notice that this large bird is not of their species, and labor to meet the demands of this large juvenile for food.


Brown-headed Cowbird

Brown-headed Cowbird
Yet another case of cowbirds parasitizing a junco pair, here a cowbird nestling growing to full size in a Dark-eyed Junco nest in Summer 2015.  The juncos built a nest in a wreath hanging on the front door of our house, and we found three eggs in it. Later, there was just one egg, and as we discovered it had been left there by a Brown-headed Cowbird pair which had removed the junco eggs. Though a nestling cowbird is much bigger than a junco, the eggs are not that different in size or appearance. Soon after this picture was taken, the nest was empty and we assumed this young cowbird had fledged.

Brown-headed Cowbird
A Brown-headed Cowbird, identified as a juvenile by the visible pink gape at the corner of the bird's mouth, photographed on Deer Isle, Maine, in August 2014. The very thick bill establishes that this is a cowbird rather than a blackbird.

Brown-headed Cowbird
A young male molting from juvenile to first-basic plumage in September.