Cowbirds? In Berkeley?

Brown-headed Cowbird (Molothrus ater)

Looking at this from below, I thought at first this was a Brewer’s Blackbird. When I got the images home and up on the screen, doubt crept in. That brown head? The dark eyes, instead of the bright yellow eye that a male Brewer’s has? This is not a Brewer’s. It’s got to be a Brown-headed Cowbird. And that spells trouble for other birds in the area — a different kind of trouble, but possibly more deadly, than the American Crows. Where the crows may try to steal the eggs of other birds, and harass their fledglings, they at least lay their crow eggs in crow nests and let the other birds lay their eggs in their own nests. Cowbirds are much more insidious. They lay lots of eggs, but don’t build nests. The female lays her eggs in the nests that other birds build. The other bird moms, most of the time, don’t recognize the fraud. The cowbird chick hatches earlier, and the other mom goes to great trouble to feed it. The cowbird chick is usually bigger, and it may peck open the other eggs and destroy them, or crowd out and smother the other hatchlings. Cowbirds are very bad news.

Brown-headed Cowbird (Molothrus ater)

Read more about cowbirds on Wikipedia Cornell Audubon.

P.S. This post was scheduled to publish on May 29 but due to a technical glitch of unknown origin, did not publish as scheduled.

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