In the winter, most people end up staying inside a bit longer than usual, curling up on the couch with a good book or movie, and layering up when they go outside. The critters that share the watershed with us don’t have the luxury of home heating, but they actually do a lot of the same things when the weather gets cold! Read on to learn more about how our furry (or feathered) friends stay cozy through the winter season.
Little brown bat (Myotis lucifugus)
Little brown bats have a widespread range in North America from Alaska to Canada, and in boreal forests south through most of the contiguous United States and into central Mexico. This bat eats a wide variety of flying insects, including nocturnal moths, bugs, beetles, flies and mosquitoes.
They live in colonies numbering in the hundreds of thousands of individuals. Colonies aggregate at nesting sites called roosts. In October and November, little brown bats leave their summer roosts and move to tunnels, mine shafts and caves. In these protected, underground spaces, the bats cling to the ceilings and hibernate, clustered against each other for warmth. In spring, they emerge in April and May. They return to the same hibernation and summer roost sites year after year.
Eastern gray squirrel
Eastern grays are large squirrels that thrive in urban and suburban environments. Have you ever noticed how busy squirrels in the fall? They spend every fall day storing food in the ground for the coming hungry winter. Squirrels make multiple food stores called “caches.” Having multiple caches means that they’ll have enough food for themselves, even if another critter finds their food. The memory center of a squirrel’s brain is very advanced, which is why they can remember where their food was buried months before.
When you think of a squirrel home, you might picture a hole in a tree. But some squirrels build another kind of home called a drey. Dreys are big messy looking balls of leaves built in the branches of trees. They are easy to see in the winter when the trees are bare. Despite looking messy they are actually built quite deliberately. Squirrels build a shell with twigs and vines and line them with moss and leaves for insulation. This insulation keeps their home warm just like the insulation in the walls of our homes.
Squirrels are generally solitary creatures. They don’t tolerate sharing their space with other squirrels unless it’s mating season, when they may share their space for a brief time with a mate. However, in the winter they will readily share their homes with other squirrels, cuddling together to share heat.
Snowshoe hare
Snowshoes in Pennsylvania inhabit mixed deciduous forests with conifers and escape cover, such as rhododendron and mountain laurel. They favor younger brushy areas, those logged or burned seven to 10 years ago. Hares also live in swamps where cedar, spruce or tamarack grow. Dense stands of aspen or poplar, interspersed with pines, might support hares. In Pennsylvania, hares live in high country such as ridge tops, mountains, high swamps and plateaus.
Snowshoe hares are about 19 inches in length and weigh 3 to 5 pounds, with males generally 10 percent heavier than females. Their body configuration is similar to the cottontail’s, although the snowshoe has longer ears, larger feet and a rangier build. In summer, a snowshoe is dark – in winter, white.
In the dark phase, its fur is gray-brown, darker on the rump and down the middle of the back, the throat buffy and the tail dark brown above and white beneath. In autumn, the dark hairs gradually fall out and white hairs replace them. This molt is irregular and might occur in patchwork fashion, but it usually begins on the feet and ears and works upward and toward the rear until the entire pelt is white (except the ear tips, which stay black). A complete change takes about 10 weeks. In spring, another molt occurs. This time, brown hairs replace white, starting with the head and back and ending with the ears and feet by late spring.
Cold temperatures and ground color have nothing to do with the pelt’s color change. It results totally from phototropism—in other words, it depends on light. As days get shorter in fall, for instance, a hare’s eyes receive light for shorter and shorter periods; this stimulates the pituitary gland, located at the base of the brain. During molt, the pituitary shuts off pigment production in the new fur, which therefore grows in white. In spring, lengthening days trigger the reverse of this process.
Red fox
Red foxes have long snouts and red fur across the face, back, sides, and tail. Their throat, chin, and belly are grayish-white. Red foxes have black feet and black-tipped ears that are large and pointy. One of the most noticeable characteristics of the red fox is the fluffy white-tipped tail. Red foxes are about three feet long and two feet tall.
In fall, a red fox hangs out mostly alone. The babies have grown up and are on their own. In the fall, they focus on food. Even for a master hunter such as a fox, winter can mean slim pickings. In cold places, red foxes grow even longer, thicker winter coats. Instead of hiding out in a den, a red fox will usually just
curl up right out in the open. Wrapped in its big, bushy tail, the fox stays nice and warm—even when it’s completely covered by snow.
To find food, foxes rely on their super sharp hearing. A fox can hear a mouse squeaking 100 yards away! When it hears a little rustle, a fox will leap into the snow and dig down to its prey.
Black-Capped Chickadee
In spring, summer and fall, the majority of a chickadee’s diet consists of animal protein: moth and butterfly caterpillars (including early growth stages of gypsy moths and tent moths), other insects and their eggs and pupae, spiders, snails and other invertebrates. Chickadees also eat wild berries and the seeds of various plants including ragweed, goldenrod and staghorn sumac. Seeds and the eggs and larvae of insects are important winter staples.
In the fall, chickadees begin storing food in bark crevices, curled leaves, clusters of pine needles, and knotholes. The birds rely on these hoards when other food becomes scarce. Chickadees also eat suet from feeding stations and fat and meat bits from dead animals.
These tiny birds are masters of winter! The black-capped chickadee has evolved some remarkable adaptations to help them survive even the most frigid conditions. Chickadees hide food carefully, develop dense winter plumage, specially select winter roosts, and even go into nightly hypothermia, thus conserving large amounts of energy.
The chickadee’s ability to go into regulated hypothermia enables it to actually lower its body temperature, in a controlled manner, to about 12 or 15 degrees F below its normal daytime temperature of 108 degrees F. The bird can conserve almost 25 percent of its hourly metabolic expenditure when the outside temperature is at freezing. The lower the outside temperature, the more energy the bird conserves.
To keep up their energy, chickadees eat like crazy all day. Studies have found that chickadees consume 60 percent of their body weight each day. They then go into hypothermia to reduce their metabolism, using up excess body fat to keep warm by shivering all night.