Pigment gene allows snowshoe hares to transform

Northwoods Notebook

The snowshoe hare has a gene that reacts to shorter days in autumn by switching off pigment as the coat grows, so the animal within weeks molts from brown to white for the winter months. (Ryan Brady/Wisconsin Department of Natural Resources)

The Upper Peninsula is far enough north to have several creatures that adjust their appearance to blend in with snow and ice.

To me, this is akin to natural magic, that within a few weeks’ time a number of animals will trade bold colors or patterns for muted shades of charcoal and white and gray, like seeing some classic cinema version. Humans only are capable of this feat with age.

This transformation can be by degree. Tawny or rusty deer become ashen in fall. Loons and grebes, too, trade colorful or contrasting feathers for slate backs and pale bellies. Bright yellow goldfinch take on an olive tinge.

But locally, the most extreme changes will be the weasels and snowshoe hares, going from brown to a camouflaging coat of almost pure white. It was impressive enough to make the diminutive ermine a mark of royalty for European monarchs.

How is this change in pelt possible?

(Betsy Bloom/Daily News photo)

A University of Montana study published in the journal Science in 2018 offered an explanation for the snowshoe hare — a gene reacts to shorter days by releasing hormones that turn off melanin production in the hair follicles for the autumn molt, switching the big-footed relative of the rabbit from brown to white for the season. By early spring, the same gene kicks the pigment back in as daylight lengthens and a brown coat begins to grow again as the hare molts for summer.

The study, led by University of Montana Associate Professor Jeffrey Good and graduate student Matthew Jones, also looked at why snowshoe hares in parts of the Pacific Northwest with little snow managed to keep their brown coats — and found something surprising.

A genetic analysis of those snowshoe hares indicated they had hybridized at some point with the more numerous black-tailed jackrabbits, also a type of hare, taking on the ability to remain brown — and thus less conspicuous to predators — in low-snow regions.

It demonstrates that “key ecological traits can seed past and ongoing adaptation to rapidly changing environments,” the study report stated.

That’s unlikely to happen with the snowshoe hares in the Upper Peninsula and northern Wisconsin, as the only jackrabbit known to be anywhere close is the white-tailed. Common in some of the Great Plains and Rocky Mountain regions, this largest of the hare species in the “Lower 48” states can be found in Minnesota and once was relatively abundant in parts of Wisconsin but now is considered virtually absent, though it might still be in some western counties.

And even if available to hybridize, it would offer the snowshoe little in adaptation to a more temperate climate — the white-tailed jackrabbit, too, turns white in winter.

Such cold-climate specialization is thought to be one reason why snowshoe hare numbers have generally declined in the region in recent years, although snowshoe hares, like ruffed grouse, also undergo regular population cycles.

Even when numbers are up when snow cover is reduced, the white hares can be tough to spot in the wild, as the species is nocturnal by nature.

Betsy Bloom can be reached at 906-774-2772, ext. 240, or bbloom@ironmountaindailynews.com.


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