You've already learned how most animals use one of three main strategies to survive each winter: migration, hibernation, or remaining active. Here are examples of physical properties that certain animals have that support these strategies.
As winter nears, migrating birds eat lots of food to add fat to their bodies. The more fat they have in store, the fewer stops they will need to make. This means other animals will have fewer chances to attack.
While most hibernating animals waken at times during winter, a bear will not—not even for a "bathroom break." Instead, its body has developed a way to recycle its own waste during hibernation.
The white winter coat of the Arctic fox acts like camouflage—a feature that helps keep it hidden from other animals. The hairs do not contain pigment, the substance that gives hair color. Because the hairs are hollow, or not filled, they trap air near the body, giving added warmth.
An alpine bird called the willow ptarmigan grows feathers on the bottoms of its feet in winter. These feathers provide added warmth. They also act like snowshoes that keep the bird from sinking into the snow.