Subnivean Survival

Winter is winding down here in the White Mountains of New Hampshire. There are still areas of deep snow, but with the increasingly variable temperatures, sometimes frigid, sometimes creeping towards balmy, spring is definitely on its way.

Rising temperatures will eventually lead to snowmelt; while hiking on trails around the Pinkham Notch Visitor Center, you will often find, this time of year, what appear to be labyrinths in the diminishing snow. These curly-q lines represent a world that many of us are completely oblivious to, a world which exists deep beneath the surface of the snow all winter. Months ago, once the snow began to fall and accumulate, dozens of a

nimals made their homes in the layers of the snow in hopes of surviving the harsh season ahead.

During the snowmelt of springtime is when we usually see the signs of subnivean habitation. The subnivean life, one which is lived below the surface of snow in the many layers where air is trapped (which then acts as insulation), can be home to a variety of rodents and other small mammals. Meadow voles (Microtus pennylvanicus) pi

ctured left, and shrews (Cryptotis parva) both typically not known to congregate in large groups, will nest together, colonizing beneath the snow. This enables them to conserve energy and keep warm. By huddling and massing together, these small mammals are able to decrease their surface area, greatly reducing the amount of heat loss. If you have a bird feeder in your yard, you can often see red or grey squirrels popping their heads up from beneath the snow, grabbing some seed and then disappearing to the safety of their tunnel.

There are even predators in the White Mountains that are well-suited for the subnivean experience, especially the ermine (Mustela erminea). The smallest member of the weasel family found in the northern forest, ermine have small and sleek bodies, which allows them to climb down into the tunnels that are dug in the snow. Ermine are important components of our ecosystem, acting as checks on rodent populations.

While hiking this spring, keep an eye out for evidence of our subnivean friends. Following red fox tracks through the woods can often lead to an area where small mammals have hunkered down for the colder months. Red fox (Vulpes vulpes) Their footsteps provide a record of their hunting excursions. are adept winter hunters, using their keen sense of smell and hearing to help them locate the networks of burrows inhabited by rodents and small mammals.

Interested in learning more about animals in the winter? Join a Naturalist Guide at the AMC’s Pinkham Notch Visitor Center for a guided snowshoe walk or hike. Call ahead (603-466-2721) for program times and details. Have a natural history question that you would like answered in this blog? Send out an e-mail to amcpnvcnat@outdoors.org.