This is Bird Note.

It turns out some birds sing to their unhatched chicks, and for a good reason too, by singing

superb fairy-rends 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 cow birds, a kind of Australian cuckoo lays its eggs in the

rent's nest, hoping to pawn off the task of parenting. But rent 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 rent eggs out, the parents may abandon the

nest, flying off to start a new family somewhere else. The password note varies among different

fairy-rend breuds. 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-rends, does your family have a secret

language? For bird note, I'm Mary McCann.