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Eastern chipmunk

It’s getting pretty cold out there. While you might be able to get cozy under blankets at home, wildlife have to be more creative to stay warm. To survive the cold and barren winter, animals use three main strategies.

Migration

Many species leave their cold habitat in search of milder climates. Bats, caribou, and elk do the same, however land migrations do not cover as much distance as flight migrations. Certain insects, such as butterflies, also migrate to southern regions for the winter. To reach their destination in time, butterfly migration starts as early as April. Fish who live in lakes that freeze over “migrate” to deeper portions of the lake. When lakes freeze over, the water can no longer exchange oxygen with the air. Sunlight is also blocked, preventing photosynthetic plants from providing oxygen. However, colder water holds much more dissolved oxygen (oxygen in its gaseous form) than warmer water. This causes fish to remain at greater depths and to slow their metabolisms to make sure they get through the winter.

Hibernation

Many mammals hibernate for all or part of the winter. In the fall, animals that hibernate eat extra food, storing it in their bodies as fat for the winter. During hibernation, animals enter a very deep sleep in which body temperatures drop and both breathing and heartbeats slow down. This requires very little energy and therefore stretches their fat supplies. Bears, skunks, and chipmunks are great examples of hibernators. Some of these hibernators store nuts and acorns in various locations to use during the last part of the winter after they wake up.

Similar to hibernation, many cold-blooded animals such as reptiles, amphibians, and fish, enter a state of dormancy. These animals often burrow into holes or mud to maintain a survivable body temperature. Amphibians and many fish will hide under rocks, logs, fallen leaves, or even bury themselves in mud under the water.

Adaptations

Animals that can adapt to the cold weather are the ones that remain active throughout the winter. The most basic of these adaptations is to grow a thicker winter coat to keep warm. Many of these survivors, such as squirrels, mice, and beavers, gather extra food in the fall and store it in caches for the winter. They will return to these locations throughout the season when food is scarce. Many animals also change their eating habits, switching to things like twigs, buds, and moss instead. However, this is not out of want. Animals eat these low value food sources because their usual dining preferences are no longer available.

Surviving winter can be hard, but life always finds a way. Take a hike some time this season and see what evidence of winter wildlife you can find.