Changing climate is driving snowshoe hares northwards

Snowshoe hares’ traditional habitat in Wisconsin may not be white enough to provide the animals with cover as the climate changes.

“The snowshoe hare is perfectly modeled for life on snow,” said Jonathan Pauli, a professor of forest and wildlife ecology at the University of Wisconsin-Madison and a coauthor of a study recently published in Proceedings of the Royal Society B, in a release. “They’re adapted to glide on top of the snow and to blend in with the historical colors of the landscape.”

The snow is vital for snowshoe hares (Lepus americanus), who rely on it for camouflage from predators. But snow is becoming less common in the southern range of their habitat in Wisconsin.

Research on the hares in Wisconsin dates back to at least 1945 when Aldo Leopold, past president and founding member of The Wildlife Society, published data on observations of the animal across half of the state, from the Mississippi River north of St. Paul to Green Bay.

Other researchers followed up on his work in following decades and the recent study shows that the range of the hares in Wisconsin is moving northwards by around five miles a decade.

“Our winter climate has changed significantly over time,” says coauthor and UW-Madison professor of forest and wildlife ecology Ben Zuckerberg.

In the present study, Pauli and his coauthors only detected hares at 28 sites of the 126 historic survey sites where snowshoe hares were observed, and only detected one hare at a historic site where they weren’t observed before.

Pauli said that having white fur on a brown background when snow melts will continue to cause problems for the rabbits. “For a snowshoe hare, being cryptic is a fundamental requirement for making a living,” he said. “It is a relatively fixed phenotype, so it is pretty clear that snow cover is one of the most important constraints in terms of where the animal can and can’t be.”

This push northward could be due to southerly hare predators like coyotes (Canis latrans) moving northwards. It could also cause cascading effects on other predators that rely in part on snowshoe hares.

Meanwhile, another recent study published in the Wildlife Society Bulletin examined ways to improve snowshoe hare detection during population counts in Michigan.