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The Brown-Headed Cowbird

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The Brown-Headed Cowbird

The ultimate in hands-off parenting

In my many years of birding, there are two things that I have learned. First, common does not mean boring; just because a particular species is common does not mean that it is not unique in some way. This is certainly true for this month’s featured bird, the brown-headed cowbird. Second, some species are tough to love, let alone like. For example: house sparrows, aka English house sparrows. What pests! I actively work at figuring out ways of discouraging these miserable creatures from visiting my backyard.  And another species that is also tough to enjoy is the brown-headed cowbird. I will explain this in a bit.

What does a brown-headed cowbird look like and where does it get its name? To begin with, the cowbird is a type of blackbird. Indeed, it looks like a blackbird with a brown-colored head (the males, anyway), though from a distance the brown coloration might appear black, giving the bird the overall appearance of a small, stocky, short-tailed blackbird—which is exactly what it is. The females are a uniform, drab, gray-brown color without streaking. The birds sport a relatively large, conical beak suited for eating seeds and insects. They will often visit your backyard feeder in small flocks.

The cowbird gets its name from its prior association with the bison of the Great Plains. Huge flocks of these birds would follow the wandering herds of bison, feeding off of the insects that the great animals would flush up through their grazing. With the demise of the buffalo herds and the western expansion of human settlement, the cowbirds followed the settlers with their domestic herds of cattle. The species now exists coast to coast.  You’ll also note that the call of the male sounds like an abbreviated version of its red-winged cousin: distinctly blackbird-like.

It was probably this dependence upon the constantly-moving buffalo herds, by which the brown-headed blackbird adopted its unique reproduction methods, that makes this bird so difficult to like. This bird is a nest parasite. That is, the female lays its eggs in the nests of other birds to be brooded and raised. The female cowbird waits for a prospective host to leave its nest for a moment and then quickly swoops in and deposits an egg. A female cowbird can lay between thirty and forty eggs a breeding season, none of which it will raise!  The most common victims are songbird species, such as warblers. The cowbird egg will hatch before the host parent’s own eggs and will then out-compete the other hatchlings for food, often causing them to starve to death. Horrid!

The problem with this species is that its presence in an area can lead to the decline of songbird species, as the host species might experience a decline in reproduction success. Nonetheless, some species have developed strategies to deal with cowbird nest parasitism. Some birds will simply abandon the nest and build another one elsewhere. Others will build a new nest on top of the old one, subsequently burying the cowbird egg. Still others will kill the invading egg or physically remove it from the nest. Yet in spite of these strategies, enough cowbird eggs successfully hatch to not only perpetuate the species, but to allow it to expand as it has.  This expansion of the cowbird range has forced some birding societies to actively cull cowbird numbers through trapping or shooting in order to protect rare and declining songbird species in specific places.

Nest parasitism: who would have guessed it? What an interesting and unique reproductive strategy. And repulsive, too! Gosh, keep your eggs in your own nest! But brown-headed cowbirds have no parenting skills whatsoever, just like some people I know.  And now you’ll view that innocent looking bird with new eyes. Welcome to my world. Happy birding!

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Author info

Michael Turnlund Michael Turnlund is a Sandpoint resident who teaches at Clark Fork High School. An avid birder, he's happy to share his knowledge of the area's avian wildlife

Tagged as:

A Bird in Hand, brown-headed cowbird, cowbird

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