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Brown-headed Cowbirds have a sneaky approach to parenthood. They lay eggs in the nests of other songbirds, and the songbird hosts often raise the cowbird chick as their own. It’s called nest parasitism. But sometimes the hosts throw out the odd-looking egg. And when that happens, the cowbirds sometimes retaliate by destroying the hosts’ other eggs. Scientists call this “mafia behavior,” likening it to organized crime groups enforcing their demands on unwilling business partners.
BirdNote®
Cowbird Mafia
Written by Conor Gearin
This is BirdNote.
[Brown-headed Cowbird song]
Brown-headed Cowbirds have a sneaky approach to parenthood. They lay eggs in the nests of other songbirds, and the songbird hosts often raise the cowbird chick as their own. It’s called nest parasitism. It exploits a songbird’s tendency to care for any young in the nest.
But sometimes the hosts catch on to the cowbirds’ ruse and throw out the odd-looking egg. And when that happens, the cowbirds have a way of dealing with this kind of disrespect.
[“Love Theme” from The Godfather]
The cowbirds sometimes retaliate by destroying the hosts’ other eggs. Scientists call this “mafia behavior,” likening it to organized crime groups enforcing their demands on unwilling business partners.
[Brown-headed Cowbird calls]
In one study of cowbird mafia behavior, host parents that accepted the cowbird eggs fared better than ones that resisted, raising more of their own young. For the hosts, the risk of losing all their eggs at once outweighed the cost of having their chicks compete with the cowbird chick.
It seems the cowbirds just want a smoothly running operation, no funny business. A little show of force now and then could help keep their hosts in line.
[Brown-headed Cowbird calls]
For BirdNote, I’m Michael Stein.
###
Senior Producer: John Kessler
Content Director: Allison Wilson
Producer: Mark Bramhill
Managing Producer: Conor Gearin
Bird sounds provided by The Macaulay Library of Natural Sounds at the Cornell Lab of Ornithology, Ithaca, New York. Brown-headed Cowbird ML120254 recorded by G. Keller, and Brown-headed Cowbird ML 197994 recorded by B. McGuire.
“Love Theme” from The Godfather, Nino Rota Geffen Records 1972
BirdNote’s theme was composed and played by Nancy Rumbel and John Kessler.
© 2022 BirdNote June 2022 / September 2024 Narrator: Michael Stein
ID# BHCO-03-2022-06-29 BHCO-03
References:
https://www.pnas.org/doi/pdf/10.1073/pnas.0609710104
http://j-avianres.com/en/article/doi/10.5122/cbirds.2013.0006
Conor Gearin
Writer
Michael Stein
NarratorSights & Sounds
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