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Learning Before Birth

Reed warbler does not realise that the cuckoo chick is not its own.

This reed warbler does not realise that the cuckoo chick it is feeding is not its own.

By Sonia Kleindorfer and Jeremy Robertson

Superb fairy-wrens sing to their chicks before they hatch, teaching them a begging call that identifies them before cuckoo chicks can predate the nest.

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Our capacity to wonder, and to communicate that wonder, sets us apart from many animals. But when does communication about the external world begin?

The BirdLab at Flinders University recently discovered that communication occurs before birth, at least in some birds, and that it is crucial for survival. We found that female superb fairy-wrens teach their unhatched embryos a unique acoustic element that is the basis of their begging call.

Our discovery came about by chance. Because nest predation is the major cause of avian mortality, we monitored the inside of nests 24 hours per day with a microphone and video camera in order to identify nest predators. We successfully observed some nest predation, but more startling was our discovery that the mother wrens sing a previously unknown vocalisation – we called it the incubation call – to their eggs for a few days before they hatch.

This struck us as odd, because a female calling in her nest several times an hour for four or five days could attract predators to her extremely vulnerable eggs or very young nestlings. This suggests there must be a very large benefit for females that take the risk of producing these calls.

After they hatched, the wren siblings in each nest produced the same begging call, and each nest had a begging call that was significantly different from the begging call given in...

The full text of this article can be purchased from Informit.