Harbour seals can learn how to change their voices to seem bigger

Consider the squeak of a mouse and the low rumble of a lion's roar. In the animal kingdom, bigger animals usually produce lower pitch sounds as a result of their larger larynges and longer vocal tracts. But harbour seals seem to break that rule: they can learn how to change their calls. That means they can deliberately move between lower or higher pitch sounds and make themselves sound bigger than they really are. "The information that is in their calls is not necessarily honest," says Koen de Reus at the Max Planck Institute for Psycholinguistics in Nijmegen, Netherlands.