Adaptations for Cold Weather
Our native wildlife has a number of adaptations that help them survive during the winter. Some animals, like many birds, simply fly south where warmer weather awaits them. Animals like groundhogs, bears, or snakes find a cozy burrow, and either fall into a deep sleep, or go into a state of hibernation. Some animals are not so lucky. How do they stay active and manage to survive until spring arrives? These year-round residents have a number of adaptations that help them stay alive until the weather breaks during spring.
For starters, these animals are usually larger than their counterparts to the south. The larger size means that there is less surface area exposed to the elements, and they can retain more of their body heat. To visualize the concept of surface area, think about lighting a large log in a fireplace, but when it is split into smaller pieces, you the surface area is increased, making it easier to burn. In the same way, a larger animal has less of its body exposed to the elements, and is able to retain more warmth than a smaller animal.
Another adaptation that animals to the north possess, is a dense winter coat of fur which helps them trap more of their body heat. This coat usually has a somewhat coarse outer layer that can repel moisture, and a thick, softer inner layer of downy hair which traps more of their body heat. On average, an animal’s winter coat allows them to retain about 80% of their core temperature. These winter coats are often darker than the summer fur, therefore trapping more sun, as darker colors do. Many animals eat a lot in the fall to put on a layer of fat, which provides two benefits: it helps with insulation, and it provides stored energy reserves, in case food becomes scarce.
Animals that live in the north, especially birds, have more blood vessels in their extremities that help to keep these areas warm, especially when they are wading in cold water. Many northern species also have thicker layers of skin, beaks, claws, and toenails.
All of these adaptations help our winter residents get by until the spring once again arrives. Despite these adaptations, the winter is the harshest season for most wildlife, and mortality can be high, especially in smaller animals like mice, rabbits, and squirrels where it is not unusual to lose 80% of the population mostly to starvation and being eaten by larger predators. These smaller animals have a higher reproductive rate to counterbalance their relatively short lifespan.
Nature Note for 1/21/2018