Loons Change Their Tunes after Conquering a New Lake

Scientists have discovered a surprising feature of the loons that reveals they are more social than previously thought. "We never give them enough credit for the knowledge they have of their fellow beings" said Donald Kroodsma, an ornithologist at the University of Massachusetts.

The loons are water birds who swim well and feed on fish. They spot their prey underwater mainly by sight, so they prefer lakes with clear water. The loons have unusually dense bones for a bird and larger loons often have difficulty taking off. They often need to run on the surface of the water for a couple of hundred meters before finally succeeding getting airborne. Apparently, they're no better at landing either.

It was previously thought that loons develop a distinctive yodel when they're young and then stick with it. Charles Walcott, a biologist at Cornell University, reasoned that this could allow the recognition of individual birds on the basis of their song. To test the idea, Walcott's team studied two populations of loons - one in Wisconsin and another in Michigan.

At first, the scientists observed that indeed the male loons' calls changed only slightly from year to year. However, they were for a surprise when they followed the loons that relocated to a different lake. 10% to 15% did so each year.
The researchers found that out of 13 males, 12 changed their songs significantly. "It came as a shock," says Walcott. "At first I didn't believe a word of it."

According to Walcott, the loon's yodels are not exactly peaceful, but translate to something like "you come here, and I'll pull all your feathers out". It turned out that they haven't just changed their songs at random; in fact, they adopted a song that would be as different from its predecessor's as possible.

The reason for doing so is to signal to potential rivals that a new master of the lake has arrived, Walcott says. This suggests that loons have richer social lives than once thought.

If you wish, you can listen to a loon's song before and after it has moved.