When winter comes to call, some critters head out of town, some put on their warm coats, some take a nap, and some go underground!
On the down low
As the temperature drops and the snow starts to fall, our mammal friends adapt in different ways. Hibernation is one way to get through winter. A hibernating mammal appears to be asleep. Its breathing and heart rate slow down. Its body temperature drops, and its metabolism gets very low. This state of slow-motion is called torpor. Since the animal is not active, its body does not need food for a few months.
The woodchuck likes to sleep the winter away in its burrow underground. This mammal starts slowing down in October, and hibernates until March or April. About once a week, the hibernating woodchuck wakes up just long enough for a quick potty break. The woodchuck’s body has a special kind of fat to help it keep warm while it snoozes. This brown fat can only be burned for heat, and not for energy, like normal fat.
Moles, chipmunks and shrews spend most of the winter underground, too, but they are wide awake. Moles are fossorial mammals, meaning they are built to dig. Moles have webbed feet with large claws, slinky bodies, and ears and eyes tucked inside to stay out of the way. Moles tunnel underground all year ‘round, but chipmunks and shrews are semi-fossorial. They scurry above ground until it gets cold outside, and then they plow under the snow, leaves and soil to eat, sleep and play until spring.
Bats hibernate during the winter in caves or other cool, dark shelters, like underground mines, cellars, or cavities in trees. They cling to the ceiling with their toes, and hang upside down. The hibernating bats’ body temperature drops to match the chilly air temperature in the cave. Bats can lose up to one half of their body weight while they hibernate. Hibernating bats are not sound sleepers, and they can easily be disturbed by loud noises or by quickly increasing temperatures. Even ten minutes of flying around when it should be hibernating can make a bat use up too much energy - so just a few interruptions can be deadly.
Instead of sticking around in the cold weather, some critters prefer to migrate. Many species of birds migrate south, where the winters are warmer and there is plenty of food. Shorter days in the fall are the signal that it’s time to fly. The birds’ natural instincts guide them on the same path from year to year and generation to generation. Because the trip is long and can be dangerous, some birds travel in large flocks. Some birds that spend the summer in Ohio and usually migrate in the fall include hummingbirds, warblers and sparrows as well as turkey vultures, great blue herons and woodcocks.
Some insects also migrate. The last batch of monarch butterflies to hatch each summer flies all the way to Mexico for the winter.
To Adapt or not to adapt? That is the Question
Many of Ohio's wildlife choose to stay year-round by staying active and braving the elements. To keep warm all winter long, animals bulk up by eating non-stop in the late summer and fall. Mammals will start to grow new, thicker fur while birds fluff up their feathers. The snowshoe rabbit and the short-tailed weasel will grow white fur in order to blend in to the surroundings. Squirrels wrap their furry tails around them like thick winter blankets. Ruffed grouse have feet that work like snowshoes, and they may bury themselves in snow drifts to keep warm. Bobwhite quail huddle back-to-back in a circle on the ground to sleep, so they can keep their tail ends warm while they keep an eye out for predators. Earthworms migrate a little - about six feet under - to keep from becoming frozen.
Birds that stick around eat seeds, nuts and berries. Backyard bird feeders are important food sources for winter birds, in addition to berry bushes, unplowed farm fields and leftover garden plants. Evergreen trees and shrubs, brush piles, and brier patches provide important cover for birds and small mammals toughing out the cold.
What about our cold-blooded friends?
Not to worry! Since amphibians and reptiles have no way of staying warm in the winter, they seek shelter underground and become inactive. Water makes a good shelter for them too, since cold water holds more oxygen than warm water. Fish, along with some turtles and frogs, move to the bottom of the lake or pond and hide out under the rocks or soil. They may even bury themselves in the mud.
Some snakes get cozy in their den and curl up together in a ball to keep warm. Wood frogs burrow under the forest floor for an amazing winter trick. Almost half of the water in the frog’s body turns to ice, its eyes and brain freeze solid, and its heart and lungs stop. When spring comes, the frozen frogsicle thaws out and it hops back into action!
This winter, take time to visit your local Ohio State Park and check out the chillin’ critters. Look for tracks in the snow, and listen for movement in the trees and brush. Never disturb a migrating animal, though!
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