Research finds some birds kill chicks

[Donna]

SANTA CRUZ, Calif. – In a world of birds that shirk parenting by laying eggs in each others' nests, University of California Santa Cruz researchers have observed in the wild one species that can recognize and kill the freeloading chicks it was tricked into raising.

The American coot, an aggressive marsh bird, uses the first-born in each set of coot hatchlings as a template, said lead researcher Dai Shizuka of the UCSC Department of Ecology and Evolutionary Biology. If other hatchlings in a batch match, they are accepted. If not, the parasite chicks can be violently ousted.

It's a costly gamble for females that make more eggs than they can care for and hatch more chicks than they can possibly feed.

"Most parasitic chicks don't make it because of egg or chick rejection," said Shizuka, a recent Ph.D. gradaute. However, "you lose out if you don't play the game. Everyone's trying to sneak one past each other."

Most of the time, the first-born coot belongs to the parents, but in experiments done with Bruce Lyon, professor of ecology and evolutionary biology at the school, Shizuka placed a foreign coot as the first-born, and the parent still used it as a template, rejecting instead its own babies.

The research doesn't yet explain how coots distinguish chicks, maybe through song or feather patterns, but it places them on the opposite wing of birds that can't tell a foreign chick, wasting food resources on something size, shape and often species-different.

The findings are surprising, but solid, said Stephen Rothstein, University of California, Santa Barbara, professor of zoology, who studies one of the lopsided parasitism cases, the brown-headed cowbird, often larger and earlier-hatching than the host's chicks. In the case of the cowbird, the host often loses all its babies, he said, so the parasitism is more harmful, but "here you have a case where the discrimination task is more difficult and the cost is less."

But why kill, rather than shun a seemingly defenseless chick? Wesley Hochachka, assistant director of bird population studies at Cornell Laboratory of Ornithology, said coots are likely protecting their own.

If you're snubbing a kid, it's going to follow you and going to be loud about it. It could draw attention to you, and something that might want to eat your kids," he said.

[valhalla]

I've only seen the coots in the winter months hanging out with ducks, so I didn't know they were aggressive.  Learn something new every day