Chipmunks, woodchucks, ground squirrels, jumping mice and bats are on the list of true hibernators. During hibernation they are very hard to wake up. Their heart rate, respiration and body temperature drop dramatically. In contrast, animals that aren’t true hibernators–like bears, raccoons and skunks, wake easily and don’t have such dramatic drops in temperature and heart rates. For example, a sleeping bear’s temperature only decreases by about ten degrees and they breathe only a few breaths slower. Interestingly, bears can go more than 100 days without eating, drinking or passing waste and females actually give birth during their winter sleep! Imagine waking up after a long nap to find a baby snuggled by your side!
During winter a chipmunk’s heart rate drops from 350 to only 4 or 5 times per minute. Their body temperature goes from 96-104 all the way down to 42-45 degrees F during winter. And while they might take 60 breaths per minute during the rest of the year, during hibernation, this drops to fewer than 20. If you discovered one, it would likely be curled up in a tight ball and looking for all intents and purposes, dead.
In the winter during periods of no snow or warm temperatures, chipmunks might rouse from their sleep and emerge from their dens, especially if the fall produced a good harvest of nuts. Chipmunks are notorious for filling their cheeks full of nuts, seeds, berries and grains. They take these back to their underground burrows–which may be as long as ten feet–and deposit them in special food chambers. These may contain hundreds of nuts by the time winter arrives. They also have separate tunnels for their “toilet.”
Chipmunks are the smallest members of the squirrel family, weighing in at 1-5 ounces. During hibernation their weight may drop by half! Many don’t make it through the winter because their fat reserves run out or they are found by predators, like a fox or coyote and don’t wake up before they are eaten.
Chipmunks, like the golden-mantled ground squirrel, excavate burrows in the ground unlike other squirrels like red, gray and flying squirrels that make their homes in treetops or in hollow cavities in trees. On average a chipmunk in the wild lives only 2-3 years.
To read more about bats and some of the troubles that they are having lately while they hibernate, click HERE, or about gray squirrels and how they spend their winters, click HERE. For this week’s puzzler, Click HERE.