So what's black and white and can count? Penguins calculate

KING PENGUINS have developed an innate sense of mathematical ability that enables them to find their mate in a crowd of thousands. Scientists have discovered that king penguins are able to calculate precisely how much louder they should call to a loved one to overcome the extraneous noise of a windy day.

The penguins nest in colonies of tens of thousands of breeding pairs and identifying the call of their mate is the only way of ensuring they can feed during the months it takes to hatch an egg and rear a chick.

Females and males can spend two or three weeks on the nest while their mate hunts for fish. Being able to recognise the call of a returning partner is vital for survival, enabling the pair to switch roles. In windy weather the noise of the colony increases because of the sound of the wind and the increased din from other birds trying to make themselves heard.

Dr Theirry Lengagne and colleagues at the Universite Paris Sud in Orsay tagged and recorded the calls made by 30 pairs of king penguins during the summer breeding season of a colony of 40,000 pairs nesting in the Crozet archipelago of the southern Indian Ocean.

They found that the penguins were able to calculate the amount of background noise of the colony and compensate their call. "For the first time, to our knowledge, we have shown that a bird species takes into account the constraints imposed by wind on their acoustic communication," the scientists said. "In windy conditions, birds try to maintain the efficiency of communication by increasing both the number of calls emitted and the number of syllables per call.

"This result conforms with predictions from the mathematical theory of communication: increased redundancy in a signal improves the probability of receiving a message in a noisy channel."