Some species of cuckoo are known as brood parasites for their devious tactic of laying their eggs in other species' nests so those birds can care for the cuckoos' young. Now scientists have discovered that an Australian bird called the fairywren has evolved a way around this tactic: The mothers teach their unborn chicks a unique begging call – a sort of password.
"We call this an incubation call," said Mark Hauber, an animal behaviorist at Hunter College at the City University of New York and an author of the study, which appears in the journal Current Biology.
"The more times the mother calls, the better the mimicry of the chicks."
The teaching begins a few days before the birds hatch. And while "the cuckoo chick is very adaptable and tries out many begging calls until it sounds similar to the fairywren," Hauber said, it also has a shorter incubation period. So it hatches several days before fairywren chicks, leaving it little time to practice and perfect the passwordlike call of the fairywren mother.
Generally, when a cuckoo hatches it throws out the other eggs in the nest. When a mother does not hear her unique call from her babies, she abandons the nest.
Male fairywrens help their mates care for their young, so the mother teaches her mate and any other helpers the password through the performance of a special song.
-New York Times Service.
