The “Let’s Talk About Parks” series is designed to encourage exploration and discovery of Pittsburgh’s urban parks.
The thick of winter has settled upon us, bringing with it single-digit temperatures and snow-covered trees. While there will be times throughout the next several months where weather patterns will allow the occasional 50-degree day, a wintertime excursion into your parks will usually require some serious bundling up. Whether you’re sled riding at Riverview or Highland Park, ice-skating at the rink in Schenley Park, or picking up a trail map at the Frick Environmental Center, you will need a winter coat. You’re not alone. The wildlife that you see scurrying through your parks in the colder months of the year also need to keep warm, and many of them have special winter coats that help them do just that.
Many mammals have hair that covers their entire body — think of a squirrel or fox — in a complete coat. This coat of body hair, often called fur or pelage, can consist of several different layers. Some fur has a single layer of dense, fine soft hair called down hair, while others also have a longer layer of guard hairs. Some animals have an additional middle layer of awn hairs. All three have specific jobs to do.
The down hairs are closest to the body, and their function is thermoregulation. The down hair is fine and dense, and keeps a layer of dry air next to the skin while also repelling water. The outer guard hairs are longer and coarser, and have most of the visible pigmentation of the coat, providing the color markings that can help camouflage them. Guard hairs have hollow shafts that tend to have a glossier texture that helps repel water and sunlight, protecting the skin from moisture and ultraviolet light, while also providing insulation.
The middle layer — called awn hairs — helps the other two layers with their protective tasks. The lower parts of the awn hairs help the down hairs keep a layer of air next to the skin, and the outer parts help the guard hairs shed water. Awn hairs are generally more abundant than down or guard hair, and provide much of most most visible pelage.
The pelage of many animals changes color and thickness as the winter months roll around, sparked by the shortening periods of daylight and cooler temperatures. The changing temperature and sunlight hours spurs a part of the animal’s brain to tell its body to begin preparing for winter. As the daylight shortens in late fall, a denser and lighter-colored coat of fur grows in. The fur of some animals also changes color as the winter coat grows in. In warmer weather, white-tailed deer have a reddish-brown coat, while in late fall their pelage shifts to grayish-brown that helps them blend into the bleaker hues of the winter woods.
Not all animals have hair that is well suited for frigid winter. While opossums grow thicker winter coats, their hairless ears and tails often become frostbitten, one reason you will sometimes see a opossum missing the tip of its tail. Some animals — including fox — will grow extra hair between their pads to help keep snow from lodging in their feet. Gray squirrels also molt, shedding their summer coat and growing their winter pelage throughout September and early October, although their tails usually molt several months earlier.
One of the most dramatic shifts in seasonal pelage occurs in the snowshoe hare. While not as commonly known as the eastern cottontail rabbit, the snowshoe hare, named for its large hind feet that can run on snow, may be spotted in the northeastern part of the United States with a careful eye and a lot of luck. Pittsburgh Parks Conservancy Naturalist Educators Taiji Nelson and Mike Cornell report that while the snowshoe hare’s habitat area includes the Pittsburgh region, seeing one is extremely rare — and perhaps for good reason. Their warm weather coat is rusty-brown in color, impeccably blending with the leaves, logs and dirt of the spring and summer forest floor. As fall winds down, they lose their summer coat and grow a pristine, starkly white coat that perfectly camouflages them against the winter snow.
For a downloadable map of winter trail hikes where you may spot animals in their winter coats, visit www.pittsburghparks.org/frick-environmental-center.