How the Snowshoe Hare Is Losing Its Winter Whites

ENVIRONMENT

As the climate warms, snowshoe hares are increasingly ditching their winter wardrobes and keeping the brown fur they sport during the rest of the year. Now, a new study shows how: by borrowing a gene from a jackrabbit. (Science)

Why does the snowshoe hare change coats to begin with? Check out our terrific gallery of downloadable illustrations for some help.

Teachers, scroll down for a quick list of key resources in our Teachers Toolkit. Teaching camouflage or natural selection next year? This might be a good one to bookmark.

Snowshoe hares, like this one in Denali National Park, Alaska, typically sport a bright white winter coat.
Photograph courtesy NPS. Public domain

Discussion Ideas

 

 

The winter white camouflage isn’t working too well on this snowshoe hare in Seeley Lake, Montana.
Photograph by Dr. L. Scott Mills (Research Photo), North Carolina State University. Public domain

  • Over the last several years, fewer snowshoe hares are molting from brown to their traditional winter white. Instead, they are molting from brown to … brown. Why?
    • natural selection. Climate change has meant the winter blanket of snow is coming later and later in the year. (Learn more about the impact on snowshoe hares here.) Snow-white bunnies are very easy for predators to spot on a brownish hillside or plain. Snowshoe hares with the adaptation of a brown-to-brown molt are more likely to survive and, uh, breed like rabbits.

 

The species range of black-tailed jackrarbbits, like this one in Joshua Tree National Park, overlaps with the species range of the snowshoe hare.
Photograph by Brad Sutton, NPS. Public domain

  • The Science article associates the brown-to-brown molt with a gene borrowed from the snowshoe hare’s big-eared cousin, the black-tailed jackrabbit. Why doesn’t the black-tailed jackrabbit molt to winter white?
    • The black-tailed jackrabbit’s other name—the desert hare—gives it away. Unlike the snowshoe hare, the black-tailed jackrabbit inhabits ecosystems that stay warmer all year and are less likely to be covered in snow for months at a time. Like the snowshoe hare, however, the black-tailed jackrabbit’s coat is an excellent example of background matching: its blackish-brown and speckled-white coat beautifully matches its habitat.

 

  • How did snowshoe hares “borrow” the jackrabbit agouti gene, which prevents coats from turning white?
    • Snowshoe hares acquired the agouti variant the old-fashioned way—interbreeding.

 

TEACHERS TOOLKIT

Science: How the snowshoe hare is losing its white winter coat

Nat Geo: Camouflage illustration gallery

Nat Geo: Before and After: See Animals Change Their Coats for Winter

Nat Geo: What is camouflage?

(extra credit!) Science: Adaptive introgression underlies polymorphic seasonal camouflage in snowshoe hares

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