BOB HIRSHON (host):
A bird’s secret code. I’m Bob Hirshon and this is Science Update.
Cuckoos are famous for laying their eggs in other birds’ nests, pawning off all the care and feeding of their offspring to a hapless host parent. But superb fairy wrens have evolved a defense against the freeloaders. According to behavioral ecologist Sonia Kleindorfer ofFlindersUniversityinAustralia, mother fairy wrens sing to their eggs while they’re in the nest – like this:
(Mother incubation song)
After the babies hatch, they have to sing a special call note that matches key elements of that song in order to get fed. For instance:
(baby bird call notes)
Whether you learn the password correctly will determine whether or not you will live or die.
She and her colleagues discovered that each nest has a different password call. Baby cuckoos often don’t get the password quite right, and are often rejected by the host parents.
I’m Bob Hirshon, for AAAS, the science society.