Call of the Wild
RESEARCHERS have long believed that male loon calls, like those of most other birds, are very stable, altering only slightly over time. But more than a decade ago, Cornell University neurobiologist Charles Walcott, who has studied the same loon populations in Wisconsin and Michigan for 15 years, witnessed something that hinted at a more complex story: A vicious territorial battle between a resident loon and an interloper ended with the first loon being chased off and his attacker replacing him on the lake. The next year, the victor—now ensconced in his new territory—dramatically changed his call.
“I was astonished,” says Walcott. A colleague suggested that perhaps the new loon was imitating the bird he replaced. While he was investigating that idea and observing a dozen more territorial relocations, Walcott discovered the opposite: The interlopers actually changed their calls to sound as distinct as possible from their vanquished predecessors.—Hannah Schardt