Wildlife in Winter by Tom Cwynar illustrated by Charlet Farrar Baby, it’s cold outside! Trees have shed their leaves, and cold weather is on its way. Winter can be fun for some, but if you are a kid who shivers at the sight of an ice cube, you may be dreading the coming months. Winter means shoveling snow, traveling on icy roads and wiping your nose when the cold makes it red and wet. For wildlife, winter is even more of a challenge. When temperatures drop below freezing, animals can’t just turn up the thermostat on the wall. Nor can they go to the grocery store when they are hungry. Instead, animals have devised several ways to deal with Missouri’s winters. Some leave the state and don’t come back until spring. Others find sheltered hidey-holes and sleep until spring. Other animals remain in Missouri and stay active through winter, but even they have evolved special ways to help them survive. I’m out of here! Some animals refuse to put up with Missouri’s winters. Hummingbirds and tree swallows leave Missouri for a warm climate or a place with more food. Hummingbirds go to Central America. Many tree swallows head for the Gulf Coast. Animals that move seasonally from one place to another are called migrants. Many geese and ducks migrate south for the winter and then back north for the summer. You can see or hear their noisy, V-shaped flocks high in the air. Some geese winter in Missouri because the weather here is milder than farther north. They arrive about the time other animals are getting ready to leave. Monarch butterflies pass through Missouri in September. Most of them spend the summer in Canada and in the northern U.S. When the days start getting shorter, they head for Mexico. Animals don’t always migrate to avoid the cold. Sometimes they migrate for food. Many eagles, for example, come to Missouri in the winter from northern states and Canada to eat fish in the open waters below dams. Wake me when it’s warmer! A few animals treat winter like a boring movie; they sleep through it! A woodchuck, or groundhog, is considered a true hibernator. In late summer, it fattens itself for a deep sleep that usually lasts until winter is over. A groundhog conserves its energy reserves while sleeping by lowering its body temperature by about half. It also slows its heartbeat down to about four beats per minute from its normal 160 beats per minute. Other true hibernators include Franklin’s ground squirrels, meadow jumping mice and some bats. Do bears hibernate? Technically, no. Their sleep is not as deep as a groundhog’s. They fatten themselves before winter and their heart rate drops, but their body temperature doesn’t go down much. This is probably because black bear females are usually pregnant when they sleep, and the babies growing inside them need warmth. Bears can even nurse when they are in their winter dens. Frogs, snakes and turtles don’t exactly hibernate, but they go into what’s called torpor, or a dormant state that closely resembles death. Green frogs spend winter in the mud at the bottom of ponds. Box turtles bury themselves in soft ground. Snakes find shelter in a den or crevice and may spend the winter in a tangle of other snakes–sometimes different species of snakes. Many insects spend winter in a similar state, except that for them it’s called diapause. During this state, they use little energy, and they don’t grow. They often burrow into the soil or under rotting vegetation. Box elder bugs look for holes or small openings in the siding of houses. The small amount of heat escaping from within a house can keep a bug cozy. Some insects, reptiles and amphibians create a natural anti-freeze called glycerol in their systems. Although it doesn’t always keep them from freezing, glycerol prevents the formation of ice crystals, which could rupture cells. When the weather is really bad, we humans stay indoors. A lot of animals avoid the worst weather, too. Chipmunks, skunks, raccoons and opossums don’t hibernate, but they stay under cover and nap during the coldest parts of winter. Their naps might last weeks, but when the weather turns balmy, they venture outdoors. Where’s my heavy coat? Many animals grow a thick coat to keep them warm in winter. Deer hides and fox and coyote pelts are thickest in late fall and winter. The fur of muskrat and mink gets prime and beautiful then, too. Weasels and snowshoe rabbits grow white coats in winter. The white helps them hide when snow covers the ground. Birds often look plumper during cold weather. That’s because they fluff their feathers to hold more air next to their bodies. This insulates them from the cold. Ducks, geese and swans keep their feathers dry and warm by treating them with oil from a little oil sac near their tails. Most animals eat a lot during late summer and fall to help them survive winter. Fat can be a good thing for animals. It provides energy reserves when food is hard to find. Chipmunks, squirrels and beavers store food so they have something to eat during winter. Honeybees stay active all winter, but they usually remain in their hives. They eat the honey they have stored and flutter their wings to keep themselves and the hive warm. When it gets really frosty, bees may huddle together. They take turns being on the outside of the bee bundle, where it’s colder. People aren’t much different than animals when it comes to surviving winter. When cold weather approaches, we put up storm windows to insulate our houses. We may stock the pantry or freezer with more food. We retrieve heavy blankets, long underwear and winter coats from the back of the closet. Many people gain weight in winter. Is that because of holiday eating, or because our system tells us to put on fat reserves? Studies also show that people sleep more in winter. Is our biology telling us to go to bed? Granted, we don’t have any true hibernators among us, but there’s a kid in almost every English class that comes close!

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