Winter Adaptations of Animals
Posted On: 02/24/2017 - 11:15am, Posted By: Emily Imhoff, Collections Manager - Zoology
The winter months bring several challenges for wildlife. Low temperatures and limited food sources can be dangerous, so wild animals of all kinds have different strategies to cope with winter.
Temperature: animals keep warm in several ways. Some try to store fat on their bodies to protect their inner organs from cold temperatures. Some shiver to generate body heat. Many mammals grow a thick fur coat. Birds will puff up their feathers so they hold more body heat in the resultant air spaces. Those “fat” birds you see in the winter aren’t necessarily obese, they are just holding all their feathers out to hold more warm air! Finally, a good way to deal with cold temperatures is to stay indoors! Many animals spend lots of time in their dens, burrows, and nests. Birds often roost in groups in a nest box or other enclosed space in order to stay warm at night.
Arctic Fox fur is an excellent insulator. Notice the long “guard hairs” protruding from the shorter, dense layer of soft “down hairs."
Food: Plants usually don’t grow well during winter, so animals that rely on them for food could be in trouble! But these animals have learned how to survive in different ways. Many animals store food during the warmer months so they will have something to eat during winter. Some birds, such as woodpeckers, and mammals, such as squirrels, hide nuts and seeds in trees and in the ground for later retrieval.
Fox Squirrel (Sciurus niger) and Red-bellied woodpecker (Melanerpes carolinus) mounts from the Zoology Teaching Collection
Color: Some birds and mammals that live in very snowy regions will actually change color during winter to blend in with the snow. The Arctic Fox (Vulpes lagopus), Snowshoe Hare (Lepus americanus), and Willow Ptarmagin (Lagopus lagopus) all have coats or feathers that are mostly brown during the summer months. This lets them blend in with the soil, shrubs, and trees in their habitat. As winter comes, they will start replacing their brown coats or feathers with white ones. Once the animals have fully changed color, they blend in extremely well their snow-covered habitat. In the case of the Ptarmigan and Hare, it helps them hide from predators. In the case of the Fox, it allows them to better sneak up on prey!
Willow Ptarmagins (Lagopus lagopus) collected in Norway by Wildlife Artist John Ruthven
Dormancy: Animals can avoid some of the challenges of winter life by entering a dormant state. This way they don’t use much energy, so they don’t need as much food. Black bears (Ursus americanus), Raccoons (Procyon lotor), and Common Poorwills (a bird – Phalaenoptilus nuttallii) all use this strategy during winter, as do many species of fish, frogs, and turtles. There are different types of dormancy used by different animals, including winter rest, torpor, or hibernation. In each, the animal appears to be asleep, does not eat or drink, and has a lowered heart rate. An animal in torpor will also have a lowered body temperature and metabolism, but can still be awakened fairly easily. True hibernation is a kind of extended torpor where body temperature is even lower and the animal is not easily awakened.
Big Brown Bats (Eptesicus fuscus) move from their summer roost to a ‘hibernaculum’ in the autumn. A hibernaculum is the location where they will spend the winter in a dormant state. The hibernaculum can be a cave or an abandoned mine, or even an attic! Big Brown Bats may hibernate alone, or in small groups.
Big Brown Bat named ‘Flap’ from the Live Animal Collection. Note: only vaccinated professionals should handle live bats.
Many water-dwelling reptiles and amphibians are able to absorb oxygen from the water they live in through their skin as well as by breathing with their lungs. This enables them to survive winter underwater even when the surface of their pond or lake freezes over. These animals are typically much less active during the winter – many are dormant in burrows at the bottom of water bodies – so they don’t use much energy.
Spiny Softshell Turtle (Apalone spinifera) named ‘Penelope’. You can come visit her in the Duke Energy Children’s Museum!
Migration: Many animal species, most commonly birds, avoid severe winters altogether by moving to warmer parts of the world. You’ve probably heard the phrase “flying south for the winter” in reference to birds, or the term “snowbirds” to describe people who head to Florida for the colder months. Did you know that Monarch Butterflies also migrate? In the fall, adult Monarch Butterflies (Danaus plexippus) in the United States and Canada migrate to southern California, Mexico, or Florida to overwinter in a warmer location.
Monarch Butterflies from the Entomology Collection
Think of some of your favorite animals – do they have strategies for dealing with winter? Maybe even something not listed here! How do you cope with the winter months?
If you would like to learn more about how North American wildlife species survive the chill of winter, you might enjoy this book: “Winter World: The Ingenuity of Animal Survival” by Bernd Heinrich