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Seabird Siblicide

July 21, 2008

A seabird’s chicks fight their siblings to the death.


A seabird’s murderous tendencies….I’m Bob Hirshon and this is Science Update.

A seabird called the Nazca booby nests on islands in the eastern Pacific. Pairs often produce two eggs, but only one chick ever makes it out of the nest alive. That’s because the older chick fights the younger one to the death. Biologists Martina Muller and David Anderson and their colleagues at Wake Forest University recently identified what’s behind this murderous behavior: the hormone testosterone. Anderson explains.

DAVE ANDERSON (Wake Forest University):
This species has elevated androgens compared to their relatives that don’t have these lethal fights. When they do have a fight they elevate their testosterone even higher.

And when these aggressive chicks grow up, they seek out new hatchlings to bully. Anderson says high testosterone levels early on could also have permanent behavioral effects in other animals, including humans. I’m Bob Hirshon for AAAS, the science society.