How Does Wildlife Survive Winter?
When weather warms, even if just on a sunny winter day, these brumators may take that opportunity to drink water and catch some rays. undling to brave winter weather, are you also concerned Birds often take a different route than mammals or reptiles – about the local wildlife that lives outdoors year-round? they just leave. Not to worry. These species have evolved to survive and Birds who do not have natural foods readily available in thrive in these freezing-cold temperatures. winter can migrate short or long distances until they reach their For most, food availability is the main factor that makes wintering grounds where resources are more plentiful. Some winters such a challenge. Those with a constant winter food birds stay put. They may have a steady food supply (such as supply may stay active. These warm-blooded mammals may Photos courtesy of BRWC protect against the cold by growing thicker coats or bulking up Tri-colored bats will enter a state birds of prey) and others stay year-round and are able to adapt during the plentiful spring and summer months. of torpor over the winter months. their diets to seeds or berries that are produced in winter. For birds that stay through the winter, packing on body Foxes, raccoons, squirrels, and others rely on these methods. weight in the spring and summer is important, but their feathers Those who no longer have a food supply, such as groundhogs that also play an important role. They trap pockets of air close to the rely on large volumes of plant material, or the bats that count on body, creating a layer of insulation, which is why feather down large insect populations, torpor or hibernation is the best option. is a commonly used as insulating material. Torpor is a low-energy state where breathing, heart rate, and You may see birds “fluff up” in the winter as they try to trap body temperature are lowered so that metabolism slows and the the maximal amount of warm air in their feathers. Birds keep animal requires less energy. Bats enter torpor when temperatures their feathers well-conditioned and waterproof using oil from drop too low. Animals in torpor will awaken occasionally their uropygial gland (over their rump) so that the feathers can throughout the winter to hunt or forage, urinate and defecate, Chipmunks are an example of continually provide this essential service. and perform other functions as needed. true hibernators. In the cold, birds also tuck their feet up or their beaks into Alternatively, some mammals, like groundhogs and their back feathers. These featherless body parts get cold quickly chipmunks, are true hibernators. Hormones and declining daylight hours induce hibernation in these species and metabolism is reduced to and tucking them into the warmer core-area keeps those parts comfortable. The cold hard truth: Our native wildlife handle winter in many different ways, between one to five percent of normal. These animals lower their temperatures but rest assured, they’re just fine out there. and heart rates significantly and cannot be easily roused. Reptiles and amphibians have their own type of dormancy called brumation, which is similar to torpor. Because they cannot regulate their body temperatures, Details: Jennifer Riley, DVM, is the hospital director at the Blue Ridge Wildlife Center they begin seeking shelters or burrows as the weather cools. As temperatures in Millwood, the only dedicated wildlife hospital in Northern Virginia. It assists more approach freezing, they shut down many of their physiological functions. than 3,000 native wildlife annually. Visit www.blueridgewildlifectr.org.
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By Jennifer Riley
MIDDLEBURG SUSTAINABLE COMMITTEE| Holiday 2023
