A Winter's Worth of Sleep

After experiencing a January thaw here in Pinkham Notch, the cold temperatures are back, and with a vengeance. Bundling up in extra layers, cranking the thermostat, loading up the wood stove, and spending more time indoors are ways many of us who live and work in the White Mountains adapt to sub-zero conditions. Animals that remain in the region for the colder months also adapt in various ways, and a few species even sleep or hibernate throughout the winter.

True hibernators are few and far between here in New Hampshire; they're limited to little brown bats, the woodland jumping mouse, and woodchucks (also know as groundhogs). These animals just don't sleep through the winter- they're able to decrease their metabolism rates so much that they're pretty much in a state of supsended animation (for all the science fiction fans out there). They're body temperatures drop precipitously, as do their heart and respiration rates. Many people have heard about the white-noe syndrome, a fungus that is devastating bat populations throughout the Northeast. First seen in New York State, it has since been tracked East through Vermont and into New Hampshire. This fungus draws bats out of hibernation early, when there aren't enough food resources for them. The bats then are forced to rely on stored fat, but due to the increase in their energy use/metabolism rates, the fat is quickly and detrimentally diminished.

If the above species are the only true hibernators in New Hampshire, what about all the other animals that we hear about sleeping through the winter?

Black bears (Ursus americanus), are well-known for their deep winter sleep. These omnivours mammals spend the months of autumn eating nuts and mast in the hopes of building up body fat to help nourish them throughout their winter rest and can often be roused from their slumber during periods of increased temperatures or thaw. Female bears give birth every other year in the month of January; the new mothers are able to nurse their young due to their increased body fat that they developed in autumn.

Another "super-sleeper" found in Pinkham Notch is the Eastern Chipmunk (Tamias striatus). Due to their inability to store enought body fat, this precocious member of the squirrel family is active periodically throughout the winter. During the fall, chipmunks can be seen and heard running throughout the forest floor collecting seeds and nuts to cache, or store, for the upcoming colder months. Burrowing through the ground, chipmunks create a network of tunnels where they store food and evade predation. They wake-up from their naps in order to eat.

Interested in learning more about the natural history of the White Mountains? 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

Kassie Fenn
AMC Naturalist Guide