
Rivera-Cáceres studies bird song, and that day she was listening to the canebrake wren, a brown bird whose bland appearance (it was once named the "plain wren") belies an unusual and extremely complex call.
Canebrake wrens are songbirds, the subset of species whose calls develop beyond the standard tweet or chirp into full-fledged ballads -- and within that group they are part of a somewhat exclusive club: duetting birds.
When two of these wrens communicate, they weave their songs into an elaborate, Sonny and Cher-style duet. They warble back and forth, literally finishing each other's phrases, with such high coordination that, to an outsider, they sound like a single voice.
But as Rivera-Cáceres sat listening that morning in 2011, she noticed something odd about this pair's effort: their duet was really bad.













Comment: See also this recent report from further south on the Canadian east coast : Wrong place, wrong time: Tricoloured heron and great white egret turn up in Nova Scotia, Canada