Washington, July 27 - Only a handful of social animals -- songbirds, some marine mammals, bats and humans -- learn to actively style their vocal communications. Babies, for instance, start by babbling, their first chance to experiment with sounds.

Now, new research in songbirds shows that vocal experimentation may begin with their earliest vocalisations -- food begging calls and perhaps for a more devious reason than previously believed.

'It may have started as cheating,' said Fernando Nottebohm, head of the Laboratory of Animal Behavior at The Rockefeller University.

'By generating a diversity of calls, young birds may trick their parents into losing track of whom they last fed, in effect creating the impression of several individuals.'

In this scenario, the most agile vocal dissembler would get more than its fair share of food at the expense of its siblings.

Nottebohm and Wan-chun Liu, research assistant professor who made the original observations, are quick to say that the interpretation remains speculative for now, but if true, it would complicate the conventional wisdom that vocal learning evolved as an adjunct to reproductive behaviour.

In temperate climates, most often only male songbirds sing. The message conveyed by song is simple: I am a male robin, mature, single and ready to breed; females are welcome, males stay away.