Hibernation

Hibernation is underway in our woodlots. We can let the dogs out in the evening without worrying about them bumping into raccoons, skunks, porcupines and bears. Or…can we? Sometime during the night a small animal chewed the bottom out of the mesh bag and dropped the suet to the porch floor.

Late one December I stumbled upon a soaking wet carcass.  I assumed from its black fur that a neighbor’s cat had fallen prey to a coyote or fox until I got closer. The smell wasn’t strong but it was unmistakable and I didn’t need a closer look to know that a skunk had come out of it’s den for a walk in the snow.

In elementary school, we learned these animals fell asleep in a cozy den and didn’t wake up until spring. I was in awe of the bear’s ability to give birth while sleeping, and of the cubs’ ability to find their way to nurse all winter. Should have known that was too good to be true.

Maine’s True Hibernators

There are three true hibernators in Maine. The little brown bat, struggling with white nose syndrome, went to their hibernacula in September and October to spend the winter and don’t emerge until early to mid-spring. Unless you have a cave, mine or empty building in your woodlot you probably don’t have hibernating bats. The little brown bat’s heart rate drops from one thousand beats per minute to five during hibernation.

ground hog, whistle pig, hibernation

Have you noticed the resident ground hogs giving your late-season garden a break? They’re the second of Maine’s true hibernators. Like the little brown bat, ground hogs settle in to hibernate in early to mid-fall. They dig a den that might be attached to the tunnel where they spend the rest of the year. It’s located below the frost line and above the water table. The ground hog’s body temperature drops to 38°, heart rate to four beats per minute, and breaths only ten an hour. If ground hogs are hibernating in your woodlot they’re most likely at the edge near a clearing.

Meadow jumping mice do well to survive winter, though many don’t. Unlike most animals preparing winter, jumping mice spend only two weeks fattening up. Their den is a small chamber less than two feet below the surface, often beneath logs. Once dug, jumping mice line the chamber with dry plant material, close the opening with soil, and don’t emerge until spring. Unlike other rodents that stash seeds for winter, jumping mice don’t need them. They won’t wake to eat or drink while hibernating.

We most often see our part-time hibernators, skunks and raccoons, during January thaw before the coldest part of winter sets in, and again in late February. In mild winters like that of 2015/16, both were out and about for two weeks starting on February 1 (raccoon) and February 3 (skunk) according to photos on our game cameras. We know now that bears aren’t the sound sleepers we once believed. They seldom leave the den in winter and when they do they don’t go far, and they don’t eat or drink. In the 18 winters we’ve spent snowshoeing our woodlot and surrounding woods I’ve seen bear tracks only twice. Loggers sometimes rouse a bear out of its den by moving a pile of logs, or sometimes a single log.

We’re more likely to find tracks in the snow than the part-time hibernators while we’re in the woods. Take a look around. Tracks tell part of the story of what animals were out and about when least expected.