Cottage Q&A: Why are these loons gathering in groups?

Four loons grouped together on the lake By Bake's Photo/Shutterstock

I’ve seen loons gathering in a big group on my lake in late summer and early fall. I thought they only stayed in pairs. What’s going on? And why have I never seen them do this in the spring?—Vanessa Robert, Canoe Lake, Ont.

It’s called rafting. At the end of August or early September, before they migrate, loons typically congregate in groups on large lakes. During the breeding season (April to June), loons are very territorial and “usually don’t tolerate each other,” explains Michel Gosselin, an expert at the Canadian Museum of Nature in Ottawa. Loons will violently defend their territories against other loons, sometimes fighting to the death. They also drive off other birds and marine mammals. As the summer comes to an end, however, this territorial instinct wanes.

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Biologists believe rafting helps the birds feed more efficiently—if they’re sharing the feeding ground, they aren’t wasting energy defending it from each other—and may help protect them from predators. Loons also raft in their wintering grounds, on the Pacific and Atlantic coasts and in the Gulf of Mexico.

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Rafts can get huge, says Kathy Jones of Bird Studies Canada, who works on the Canadian Lakes Loon Survey. She recalls seeing a massive raft—hundreds and hundreds—on Eagle Lake, near Dryden, Ont. “It literally was loon upon loon. It was a wonderful thing to see.”

This article was originally published in the October 2010 issue of Cottage Life magazine.

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