Aug 21, 2013 | Featured in: Watching Backyard Birds, August 2013

The Chipping Sparrow and the Cowbird

Cowbirds are notorious for laying their eggs in the nests of other birds. The nestling cowbirds often outcompete smaller nestmates. This has caused a decline in many songbird populations.

I know the facts. Female cowbird lays egg in another species' nest. "Adoptive" parent raises oversized child, oftentimes at expense of own young. That's what the head knows. But the heart has a hard time with the cold hard facts.

I know—I just witnessed it. One of my favorite summer birds, a handsome chipping sparrow, duped into raising a bird that has grown to what looks like twice the sparrow's size: a fledgling brown—headed cowbird.

It breaks my heart to see it, and I walk towards the pair as if that would break up the relationship between adult and young. But of course, it doesn't. And it shouldn't.

My heart goes out to the little sparrow. It went through the rigors migration to return to this central Illinois yard with one purpose: breeding. It built a nest of grasses and laid three eggs, unfazed by the presence of one oversized egg, dropped in by a nomadic cowbird while the sparrow was away from the nest.

As the eggs hatched, one nestling grew faster and bigger than the rest. It demanded more and more of mom and dad's time and food and energy, while the smaller babies that shared their nest received less and less time and food and energy from the otherwise attentive parents. Perhaps, maybe even likely, the baby sparrows perished, starved of the necessary nutrition or nudged out of the nest prematurely by their oversized nest mate.

It is hard to see the petite sparrow parent next to the fluffed—up baby cowbird, the former trying to keep up with the latter's appetite, until finally the cowbird is off on its own.

And the chipping sparrow is left with none of its own progeny to show for this nesting attempt, and maybe for the entire season. It will migrate south in fall, empty—handed so to speak, but seemingly unaware or unfazed by its failed reproductive season.

Seeing part of this drama play out is hard for us humans. We want to intervene somehow, but we can't and shouldn't. For me, it took a big dose of Zen to accept this seemingly cruel act of nature. It has been going on for centuries, and will continue for centuries more. More of this goes on than we humans ever witness.

This is the price we pay when we invite birds close to us and observe their every action. We take the good with the bad when we bring birds into our backyards, where the joyous beginning of life plays out along with the sometimes—brutal end. We're bothered more than the birds are. Their instincts help them just carry on, while sometimes our hearts ache while witnessing the everyday cycles of life in the avian world.

About Nancy Castillo

Nancy Castillo is co-owner of the Wild Birds Unlimited Nature Shop in Saratoga Springs, New York. You can follow the bird activity in her yard at The Zen Birdfeeder blog.

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