The Bird Way: A New Look at How Birds Talk, Work, Play, Parent, and Think

by Jennifer Ackerman

At least the arrangement is egalitarian. “Which unfortunate female lays first seems to be a toss-up,” says Riehl. It doesn’t have to do with her age or experience or how long she has been part of the group. Once a female lays her own egg, she stops ejecting the eggs of others, and once all the females have begun laying, the destruction ends altogether.

birds living in larger groups were better at solving cognitive puzzles than those living in smaller groups.

“If a female comes to the nest and finds an egg there before she has started laying—she sees that as a parasitic egg, so she gets rid of it,” says Riehl. Greater anis don’t like to have eggs in their nest before they’ve laid. It’s like if you’re expecting a baby, and you come home and find a baby in the crib—well, it’s probably not yours. It’s just as David Davis said, ‘Anis are like parasites that have become host-specific on themselves.’” The anis’ extraordinary group display behavior—unique in the bird world—arose only after they had begun breeding communally. In other words, the greater ani’s way of breeding is evolving. “This is a very plastic behavior,” says Riehl. “Right now, it’s a mix of vestiges of parasitic behavior and adaptations to group living, like communal displays and collective decision-making. The birds haven’t gotten to the point where they all just coordinate reproduction perfectly.”

(In 2013, scientists found that the global distribution of brood parasites and cooperative breeders overlapped closely, offering evidence that cooperative breeding may evolve as a defense against brood parasites.)

We understand now that birds are not just biologically distinct but culturally distinct—and that this is true even within a species. Birds learn styles of singing, bower building, playing that vary from one place, one population, to another.