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It turns out some birds sing to their unhatched chicks. And for a good reason, too. By singing, superb fairy-wrens in Australia teach their embryonic chicks a secret code. “This ‘incubation call’ contains a special note that acts like a familial password.”
Later, in the darkness of their domed nest, this password enables the adult birds to tell who is and who is not their baby.
Like cowbirds, a kind of Australian cuckoo lays its eggs in the wren’s nest, hoping to pawn off the task of parenting. But wren chicks learn their mother’s song, and incorporate the password note into their begging calls. If the call is right, the chick gets food. But if the cuckoo hatches first and pushes the wren eggs out, the parents may abandon the nest, “flying off to start a new family somewhere else.”
The password note varies among different fairy-wren broods. It’s like a last name, “a signature of identity that unites a family. The females even teach these calls to their partners,” and use them “in their own begging calls when the males return to the nest with food.”
Like superb fairy-wrens, does your family have a secret language?
Linda Macaulay recorded this pair of superb fairy-wrens in New South Wales, Australia. For BirdNote, I’m Mary McCann.
Bird sounds provided by The Macaulay Library of Natural Sounds at the Cornell Lab of Ornithology, Ithaca, New York. Songs and alarm calls of Superb Fairy-wren  recorded by L. Macaulay. BirdNote’s theme music was composed and played by Nancy Rumbel and John Kessler. Producer: John Kessler. Executive Producer: Chris Peterson. © 2013 Tune In to Nature.org. July 2013. Narrator: Mary McCann