What Is a Winter Adaptation?

Thicker fur is a common winter adaptation for animals.

Waking up to that first brisk morning in autumn serves as a reminder to all living things that adjustments need to be made to get ready for the changing environment that comes with the approaching winter. Winter adaptations come in many forms: some animals leave colder climes to winter in warmer climates; some sleep through the winter; and others make minor physical adjustments and hang tough until spring rolls around.

Migration

Migrating birds move to warmer areas during the winter.

In order to survive the winter, some animals move to warmer climates. Several bird species fly thousands of miles to warmer climates with their migration evident as they move in large groups through the chilly autumn skies. Most mammals move only as far as needed to find reliable food sources for the winter. Caribou and some bat species are notable exceptions that have been known to migrate great distances.

Hibernation

The woodchuck is a true hibernator.

Few animals go into true hibernation during the winter. Hibernation is risky and requires significant preparation. A layer of fat, called "brown" fat, must be accumulated over the summer to provide sufficient energy to survive the winter in a deep sleep. Certain species of bats, squirrels, mice and woodchucks are true hibernators. During hibernation, the animal's heart rate, body temperature and respiration drops dramatically to help conserve energy. Hibernators do wake up periodically to defecate and stretch stiff muscles.

Dormancy

Bears become dormant in the winter.

Many people think of bears as hibernators. But they, along with chipmunks and a few other small mammals, instead go into a state of dormancy. This type of hibernation is referred to as "torpor," which is a state of deep sleep where the animal's metabolism decreases significantly and respiration becomes infrequent and shallow. While this sounds similar to hibernation, there are more frequent periods of wakefulness for these animals.

Endurance

Adaptive features such as downy feathers help animals to endure cold weather.

Some animals neither migrate nor sleep through the winter, but instead make adjustments and endure winter in their own habitat. Evolutionary changes have developed over time in the form of thicker fur, downier feathers and fluffier tails. These animals have also become master nest builders and food hoarders. Animals that tough out winters eat more heartily in the summer in order to store "brown" fat for warmth and sustainability should food become scarce. Although they don't necessarily become dormant, all animals decrease physical activity during winter to save precious energy.

Considerations

Fir trees are built to survive in the snow.

Plants and insects have to make winter adaptations as well. Insects survive the winter through a variety of methods: some spend the winter in various developmental stages such as egg, larvae or pupae; adult insects might insulate themselves underground or in large groups; some have the ability to weave cocoon-like structures that provide warmth; and others have evolved the ability to produce an anti-freeze-like substance that keeps their blood flowing in the cold.

Trees also adapt for winter. Deciduous trees drop their leaves to reduce the amount of water needed for survival and snow doesn't stick to bare branches as it would to a canopy of leaves, which reduces the risk of snapping branches due to heavy snow. Non-deciduous trees such as conifers have winter-adaptive properties like branch structure and a wax-like substance on their needles that protects them from the cold and makes snow slide off them.

References

• Michigan Forests Forever Teacher's Guides: Winter Adaptations of Animals
• Winter Adaptations
• Smithsonian National Zoological Park: Animal Adaptations for Winter Survival