The days are beginning to get a little longer, seed catalogs are filling the mailbox, and I'm starting to get milkweed seeds ready for planting. We still have a couple of months left of winter. My woodpile is starting to dwindle, but I still have plenty to make it through the remaining days of cold.
But, what do mammals do to get through the long, dark days of winter? They have a few different strategies. Animals, like squirrels, remain active during the Winter. We have all seen those extra chunky squirrels during the late Fall and Winter. Extra weight can help an animal stay a little warmer, but more importantly, if the weather is bad, and they can't get out to search for food, their body will be able to convert the fat into the energy they need to survive.
Some mammals in other parts of the country might migrate in herds.
Now, what about hibernation? Not all mammals that hibernate are 'True' hibernators. A true hibernator, like chipmunks, will go into a burrow or den, and as the temperature drops, their body temperature also drops. It can go from being around 100 degrees down to just above freezing at 35 degrees. Their heart rate will go to about 1 beat per minute, and their brain activity will nearly stop. In Spring, as the weather gets warmer, their body temperature and brain activity increases, and they begin to wake up.
Bears, skunks, raccoons, and opossums are not true hibernators. They can spend extended time sleeping, but their body temperature does not drop as dramatically as a true hibernator. They might only drop between 5-10 degrees below their normal 100. These animals will wake up on warmer days, and venture out to look for food.
Many mammals will also grow a thicker fur coat in the Winter.
To learn more about Hibernation, check out this wonderful book by Bobbie Kalman, entitled 'What is Hibernation?'
Squirrels are good at finding food that they have 'squirreled away' for a Winter day.
Chipmunks will fill their burrows with comfy, warm bedding and food stores. The food will be for when they begin to wake up in the Spring.
Bears will build up fat stores in their bodies that help them to survive. Bears are not true hibernators. They will spend days sleeping, but will wake up, move around, leave the den, and search for food.
Photo courtesy of Wayne McGee, owner of Alaska Trophy Adventure Lodge.
Raccoons will huddle up in groups in dens, or tree cavities for warmth.