The Telegraph
Since 1st March, 1999
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Crack baa code to track lost lamb

Sheep have a “baa code” to make it easier for them to tell each other apart in flocks.

The call of a sheep is so distinctive that a ewe is able to find her lamb easily amid a flock, and vice versa, by listening for the distinctive vocal signature, according to French scientists.

Earlier work by Prof Keith Kendrick in Cambridge showed that, even though sheep do not all look alike, as many humans think, the visual recognition of lambs by mothers takes weeks to develop after birth.

A simply voice recognition system enables ewes to find their lambs. Now a French team has analysed the calls of ewes and lambs and by modifying and playing them back to the animals, found that they can recognise each other using “frequency coding” to tell one baa from another.

The baa code — its pitch and timbre — is a giveaway, says the study by Amanda Searby and Dr Pierre Jouventin in the Royal Society’s journal, Proceedings B.

This vocal recognition system, previously unknown in sheep, is simpler than those found in some highly social birds and mammals, said Miss Searby of the Behavioural Ecology Group, CEFE-CNRS, in Montpellier.

When a ewe is separated from her lamb by some distance, she can still recognise it by its appearance but the sound of its baa would be crucial if the lamb was in a flock.

The frequency coding is very close to what humans use, said Miss Searby. “However the human system is more complicated: humans can rely on the pronunciation of the words, the accent, the speed of the speech. “I’m sure you would recognise me because of my French accent more than the timbre of my voice.”

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