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Apr 10, 2012

Never builds its own nest...

Photos by BarrytheBirder

Brown-headed Cowbird
Molothrus ater

Brown-headed Cowbirds have been at our feeders, in southern Ontario, for a month now and the females have joined the early males.   In due course, the female cowbirds will begin to lay eggs, but not in their own nests.   They will parasitize a wide variety of other birds' nests, both bigger, but usually smaller, and the nests can belong to as many as 220 host species.   About 140 different species are known to actually carry through on the raising of cowbird chicks.   To maximize her chances of having her young reach maturity, a female cowbird will lay as many as 36 eggs in the breeding season.   Cowbirds have adapted well in the last few centuries as they have gone from trailing buffalo herds across the prairies to showing up regularly at backyard birdfeeders.   Judging by the picture below, taken in my backyard, they are fairly agreeable at sharing their food as they find it.

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