Life Mafia Birds
posted by on March 7 at 11:09 AM
News from the animal kingdom:
Raise my kids, or else! People have long wondered how cowbirds can get away with leaving their eggs in the nests of other species, who then raise the baby cowbirds. Why don’t the hosts just toss the strange eggs out? Now researchers seem to have an answer — if the host birds reject the strange eggs, the cowbirds come back and trash the place.The so-called “Mafia behavior,” by brown-headed cowbirds is reported in this week’s online edition of Proceedings of the National Academy of Sciences.
“It’s the female cowbirds who are running the mafia racket at our study site,” Jeffrey P. Hoover, of the Florida Museum of Natural History and the Illinois Natural History Survey, said in a statement.
“Our study shows many of them returned and ransacked the nest when we removed the parasitic egg,” he explained.
This is a cowbird:
Interesting... but on some level that's not a very satisfying explanation. Lots of bird species engage in "brood parasitism" (leaving their eggs in the nests of other bird species) and none that I know of back it up with a mafia-type threat. Most trust to camouflage, or to the propensity of their hatchlings to kill the host bird's young and dominate the nest. The mafia threat involves a form of delayed cause-and-effect reasoning that seems beyond the intellectual capacities of host bird species (cowbirds are plenty smart).
Also, that is a very odd picture of brown-headed cowbird. To most people, our Northwestern variety looks like a small blackbird or crow, not a beady-eyed Darth Vader.
I wouldn't want one of those things in my nest.
That's the most eerily threatening picture of a cowbird I've ever seen. The ones around here look more like... birds? They have a brown head and black/irridescent body.
Could it be a function of simple reinforcement behavior? If they attacked the nest soon enough after the other birds rolled it out, it might be enough to make the connection. I wonder if it would make the birds less reluctant to roll any eggs out of their nests.
Wench, could be...
So that's a picture (a somewhat stylized one) of the bronzed cowbird. The bronzed is slightly more threatening looking that our local brown-headed, which is the species studied in the article that Charles links references.
That bird wants to kill me.
Don't they call a group of them a "murder"?
A group of crows is a "murder". A group of cowbirds is, presumably, a "crew". Or maybe a "hitman".
"A hitman of cowbirds left the head of a horsebird in the pigeon's nest."
Yeah, I'd say "hitman".
The original article is available for free to anyone interested at the PNAS website.
The American economy is a cowbird.
The Mexican economy, more likely.
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