HAVING two voices is a real advantage in a crowd, according to Thierry Aubin
of the University of Paris and his colleagues.
It鈥檚 long been know that each of the two branches of the syrinx, the voice
box of birds, can produce sound independently, but in most birds this doesn鈥檛
seem to serve any purpose. Now Aubin and his colleagues have shown that emperor
penguins identify each other with the help of the distinctive 鈥渂eat鈥� created by
combining their two voices (Proceedings of the Royal Society B, vol
267, p 1081).
Emperor penguins don鈥檛 make nests and rely on sound to find their mates and
chicks in huge colonies. The beat sound is ideal for this, says Aubin, because
it carries well around obstacles such as other penguins.
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