Humans have become so noisy that some animals are changing their behavior just to be heard above the din. British biologist Andrew Foote at the University of Durham recently discovered that the calls of killer whales off the West Coast of the United States have lengthened significantly in recent years, apparently to counter engine noise from the growing fleet of whale-watching boats.
Meanwhile, behavioral biologist Henrik Brumm of the University of St. Andrews found that male nightingales have cranked up their mating calls as much as 14 decibels to remain audible over urban sounds. “Researchers believed that territorial birds always sing at the top of their lungs,” says Brumm, who did his research in Germany. “So I was surprised to find that nightingales do adjust their song intensity.” The payoff for belting: The most voluble nightingales probably have an easier time finding a mate and passing on their genes, he says.