As winter arrives in Alaska, the weather gets colder and the days become shorter and darker. Snow covers the ground. People begin to heat their houses and wear heavy coats outside to stay warm. But what happens to the animals? Virtually every Alaskan animal uses some type of adaptation to conserve energy and stay warm to survive the long, cold, Alaskan winter. This lesson focuses on migration, insulation, and hibernation.
Migration: Migratory animals move between habitats during the seasons to take advantage of shelter, food, water, and climates. In Alaska, animals travel to warmer places where they can find more food before winter arrives.
For example, caribou migrate between habitats during summer and winter months. During the summer, they migrate to environments that provide lots of food for themselves and their calves so they can store energy and fat before winter. For many caribou herds, the summer grounds are inhospitable during the winter, so the caribou move to a winter habitat that is more agreeable (i.e. less snow cover, warmer temperatures, more available food).
Another example is bird migration. Many birds such as the American golden plover and the arctic tern spend the summer in Alaska eating and raising their young. However, when the weather cools during the fall, they migrate south where the weather is warmer, there is little to no snow cover, and food is available throughout the winter.
Some animals grow thicker fur in the fall to stay warm during the winter. Animals such as arctic hares and arctic foxes put on winter coats for added insulation. Dogs also grow an undercoat for winter. Caribou and polar bears develop hollow hairs for extra insulation. Birds such as the snowy owl grow downy feathers.
Since all of these animals have adapted to overwinter, they are able to forage for food throughout the winter months, using food calories as another mean to stay warm. Some animals such as the raven and certain squirrels will cache food during the summer months so they have it during the winter when food is scarce.
Another behavioral adaptation for certain birds is the act of gathering together in large flocks at night to share body heat. This is called roosting. Birds will roost in shrubbery or trees (including nesting cavities and other hollowed-out spots in trees) and empty birdhouses to retain heat and conserve energy.
Hibernation is a state of inactivity or a period of very deep sleep. During hibernation, an animal’s body temperature lowers and its breathing and heart rate slows allowing it to use very little energy. Animals are able to survive periods of hibernation by eating extra food and storing body fat during the summer and fall months. They then use this stored fat to provide energy while hibernating. Bears and arctic ground squirrels are examples of animals that hibernate during the Alaskan winters. Wood frogs produce antifreeze that allows them to spend the winter with body temperatures below freezing.
Insects also look for winter shelter to stay warm. Many burrow into holes in the ground, under the bark of trees, or deep inside rotting logs to stay warm. Aquatic animals use water as a means to stay warm during the winter. When the weather gets colder, many fish will move to the bottom of lakes and ponds and may even bury themselves in the sand and mud for extra insulation. Although not technically considered hibernation, fish become dormant and are able to survive the winter without migrating to warmer waters.
Energy Conservation is reducing the amount of energy we consume or use. For Alaskan animals, it involves minimizing the amount of energy they use to stay warm and to survive the winter months. Some animals conserve energy by storing food and fat during the fall months, while others conserve energy by lowering their heart rate and body temperature during hibernation.