Penguin prowess
King penguin chicks are remarkably adept at hearing their parents' voices over the din of the colony, researchers have found. This ability, which is shared by humans, is known as the "cocktail party effect" - the human brain's capacity to filter out irrelevant background noise. King penguins breed in colonies of up to 300,000 couples. But they do not build nests, so when parents return from foraging they must find their own chicks from among hundreds of others. Scientists still do not know how they manage to do this, says Thierry Aubin at the University of Paris, France, since the combined noise made by the penguins can go up to over 70 decibels. Recently, Aubin and his team broadcast king penguin calls at different volumes in a colony. They found that a chick can recognise its parents' call even when that combines sound of other penguins honking is as much as six decibels louder.