Science: Lost in Migration

Birds that navigate vast distances are especially vulnerable to climate change

By Sarah Parsons

Illustration by Josh Cochran

Late last January, scientists in New Hampshire found something unusual on ice-covered Lake Winnipesaukee: seventeen frozen loons. Usually, changes in day length and temperature cue the threatened birds to leave in early January for their wintering grounds off the Atlantic coast; they return to the lake about four months later to breed. Biologists think unseasonably warm weather may have disrupted their migratory instincts, prompting them to linger on the lake. When conditions turned harsh mid-month, the birds were already molting new flying feathers, which usually happens after they migrate. Unable to fly away, they succumbed to the frigid conditions. “It was very unexpected,” says Nick Rodenhouse, an ecologist at Wellesley College. “If warmer winters become more frequent, [loons] could die more often.”

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Issue 25

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