by Esther Lutz, East Central Ilinois Master Naturalist for University of Illinois Extension in Coles County
How do Animals Get Ready for Winter?
The onset of cool temperatures outside and the widespread carpet of fallen leaves take me back to November days of long ago. Looking up at the barren trees and feeling the warmth of my autumn jacket, my memory returns to those crisp fall days in the late 1950's and early '60's when the men in my family prepared for that annual fall ritual that fascinated me as a child -- hunting season.
The fall was always special. I loved starting school (in those days it didn't begin until after Labor Day), and my birthday fell in September, a real important day when you're a kid. But when October rolled around, I knew that my dad and older brothers would soon be getting the hunting gear organized, their guns cleaned and ready to go. My favorite thing was knowing that my dad would soon exercise his rabbit and bird dogs out in the country so they would be healthy and fit and ready for the start of the shooting season.
I loved my dad's hunting dogs (beagles and English pointers), and one of my chores as a child was to feed and water them every night. Interacting and playing with them on a regular basis with my brothers and sisters (which my dad encouraged) helped us to develop a special bond with them, and I'm sure that they enjoyed our attention. My dad and brothers spent a lot of time training those dogs and took great pride in them and their successes in the field. So, as a little girl who vied for her dad's attention in the midst of three older brothers, I was proud that he entrusted their daily care to me. These dogs had a special purpose in the hunting ritual, so it was a treat when Dad let me tag along with my brothers on their training jaunts and I could watch the dogs work. It was kind of hard to keep up in my rubber boots through the rough terrain of harvested fields and brush, but I was determined to share in this special time with the guys and "my dogs". Looking back, I realize now that early on Dad understood my love of the outdoors and encouraged it, and my three teenage brothers were also pretty tolerant. If they resented in any way my tagging along, I never knew.
Just as my dad got his dogs prepared for the rigors of fall, so must the creatures of nature get ready for the lean, hard times ahead. Just how do so many different animals find a way to survive a long, cold period without abundant food, seeking water that is often locked up in ice and snow? The answer lies in their ability to adapt in some way, which makes it easier for them to survive. In all cases, these adaptations depend on certain structures within the organisms, but the most striking feature of all is what the organism does with the structures. This is known as behavior. What kinds of behaviors help animals to survive in winter?
Migration. To migrate means to engage in seasonal travels between summer and winter homes. When we think about animals that migrate, our thoughts naturally turn to birds. Many species of birds do migrate, and so do some mammals in our area (certain bat species), though not as commonly. And there is a lot of variation in the length of migratory routes. Some migrations are quite extensive, some are fairly short. Why do they leave the area and fly south, then return north the following spring? It is commonly believed that birds go south in winter because the food, shelter, and liquid water supplies that their species require are scarce. Certainly ponds and streams freeze over, snow covers seeds and nuts on the ground, and many insects have been killed by the cold. On the other hand, many species of birds do not migrate at all. Instead they have adapted to enduring the harshness of winter by surviving on the seeds and berries they can find instead of insects and small animals that are far less abundant in the wintertime. They find shelter in dense brush and evergreens, or in the cavities of tree snags or manmade shelters and outbuildings. If they're lucky, they will survive until spring.
Some animals find shelter and rely on stored food. While some animals do not live through the cold blasts of winter, many do survive because they are sheltered in some way and have hidden caches of stored seeds or nuts. Animals such as raccoons and squirrels may move into attics or outbuildings for the winter. (It's a good idea to regularly check our homes for openings or holes that the creatures may use to access the inside, and be sure to seal them up!) House rats and mice may live in the fields during summer but return to the shelter of our homes, barns, or warehouses when cold weather approaches. Some aquatic species remain in water far beneath the ice or in the mud at the bottom, others animals in burrows or other retreats down in the soil. Many species of amphibians, reptiles, and small mammals find shelter and become largely inactive during cold periods, then resume normal activity when the environment becomes favorable again.
Some animals hibernate. While an animal hibernates, its life processes go on but at a reduced rate. The animal gets energy from the fat that it has built up as a reserve supply in the autumn. This fat is very necessary, for some of these animals use up almost half their body weight before the winter is passed. Their body temperature, breathing and heart beat rates fall to a very low level. This is known as a torpid condition in which their life processes proceed very slowly. Life goes on, but in a greatly reduced fashion. They remain this way until spring comes again. True hibernators in our area include frogs, chipmunks, some ground squirrels, certain mice, some bats, and woodchucks. In bitterly cold weather, such animals as tree squirrels, raccoons, opossums, and skunks remain in their dens, but they are not truly hibernating. When the temperatures rise on mild winter days and nights, these animals promptly come out of their retreats to feed and move about. They will return to their shelters when the harsh weather descends once again, only coming out for good when spring weather is here to stay.
Winter weather will be upon us before we know it. As we curl up with a good book in front of the fireplace, plop a few marshmallows in the cocoa, and gaze out our frosty windows at the swirling snow, remember that the creatures of the outdoors have only three main choices: migrate, adapt in some way, or die. Amazingly, they have evolved ingenious ways to survive nature's harshest conditions. Just as my dad prepared his dogs' bodies for the fall and winter hunting season, so does nature prepare its creatures for the cold, hard days ahead. And after the bitter winds, ice and snow have subsided, as human beings all we can do is marvel when we see them venturing out once again, alive and well in the sunny, warm days of spring.