DURHAM, N.C. -- When the going gets rough, the tough apparently sing slower.
As vegetation reclaimed formerly cleared land in California, Oregon and Washington over the last 35 years, male white-crowned sparrows have lowered their pitch and slowed down their singing so that their love songs would carry better through heavier foliage.
"This is the first time that anyone has shown that bird songs can shift with rapid changes in habitat," says biologist Elizabeth Derryberry who made the finding as part of her dissertation research at Duke University.