May 21, 2009 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. She compared
recordings of individual birds in 15 different areas with some
nearly forgotten recordings made at the same spots in the 1970s
by a California Academy of Sciences researcher, and found that
the musical pitch and speed of the trill portion of the
sparrows' short songs had dropped considerably. "I was really
surprised to find that songs had changed in a similar way in so
many different populations." She then used archival aerial
photography to see how the fo