To Survive, These Animals Must Lose Their Camouflage

Snowshoe hares, all of them with vibrant white fur, “were hopping about on fallen leaves that had no snow covering,” he wrote. “The month was unusually mild, with practically no snow until the middle of the period.” It was like a vision: The animals almost glowed against the sullen, early-winter soil.

The sight so stuck with him that he described it in a scientific paper 13 years later. By that time, Wallace Byron Grange had demonstrated an intelligence, a precociousness, and a flair for prose style that matched his middle name. At 22, he had been appointed Wisconsin’s first-ever game commissioner; now, at 27, he was a publishing zoologist as well. He was particularly fascinated by snowshoe hares—and their mysterious annual change of costume.

Most snowshoe hares start the year with white coats. They “[hop] stealthily over the crust and loose snow, almost like some phantom creature, rendered relatively inconspicuous,” Grange wrote. “By late winter the surface color … is somewhat mottled, and by the time of the spring thaws it may even appear dirty.” At this point, their dark summer coat starts to come in, and “as the spring progresses, the surface tone changes from a russet to [a] less showy brown.”

Snowshoe hares are not the only animal to pull off such a divine feat. Twenty-one species—including Arctic foxes, long-tailed weasels, and mountain jackrabbits—shift their coat color through the year to match the changing seasons.

But where it was once extraordinary to catch snowy-hued animals during a snowless season, it is now far more common. As the world has warmed, snow has become a rarer sight across much of the Northern Hemisphere, and hares and foxes increasingly find themselves in “mismatch” with their environment.

For the last decade, the ecologist L. Scott Mills and his colleagues have been studying how coat-changing animals might be able to survive climate change. On Thursday, their team published a new study—the culmination of years of work combing through museum collections—that pinpoints the parts of the world where conservation work would be most likely to save coat-changing creatures.