Editor’s Note: In addition to being an outdoors writer and author, Bud Cole is a retired elementary school teacher, an adjunct community college professor and the owner and director of Three B’s Mobil Nature Center. Beginning today, his nature features will appear periodically on the outdoors page of The Republican-Herald and News-Item.
Pennsylvania’s winter weather often varies from subzero temperatures to days with temperatures in the 50s accompanied by rain. It is enough to make one wonder how the various wildlife species survive these winter conditions.
Insects, amphibians and reptiles move below the frost line where they lie dormant throughout the winter, and the majority of bird species fly south to areas with warmer weather. Many mammals, however, begin preparing for the cold winter temperatures long before they arrive.
A few mammals go into true hibernation to survive, but the list of Pennsylvania mammals that are considered true hibernators is a small one. Only the meadow mouse, the woodland jumping mouse, the groundhog and several species of resident bats go into a period of true hibernation, which is a coma-like condition.
Black bears sleep, but they can be easily aroused from their dens. True hibernation is more akin to a deathlike state in which an animal’s body systems almost cease to function.
Accompanying the meadow jumping mouse, also called the kangaroo mouse, is the woodland jumping mouse as Pennsylvania’s only hibernating mice. House mice, deer mice, white-footed mice, meadow mice and pine mice remain active throughout the winter.
By early November the jumping mouse takes on a heavy layer of fat and spends the winter curled tightly into a ball in an underground nest protected from water and frost. Remaining in a state of unconsciousness is the jumping mouse until about the end of April, continually drawing nourishment from its stored body fat.
Groundhogs retire to their burrows as the first heavy frosts arrive, using a side tunnel to curl up much like the jumping mouse, spending the winter in a death-like sleep. Groundhogs, also known as woodchucks, store no food in their winter burrows and exist totally on the rolls of fat built up during late summer and fall.
Although Groundhog Day is celebrated annually Feb. 2, few — if any — groundhogs emerge from their dens at that time. With no calendar in the burrow they continue to hibernate until the warmer days of late February or early March, and research indicates that males often leave their dens several times during the hibernation period to check out the weather before permanently leaving their winter dens for their warm season activities.
Nine species of bats have been identified as residents or part-time residents of Pennsylvania and all belong to the same scientific family, the evening bats. Common bats that stay here and hibernate are the little brown, big brown, keen, Indiana, Leib and pygmy.
Each species of mammals that are not true hibernators have developed special adaptations to stay alive during the harsh winter weather.
Raccoons are out and about as long as the weather does not become too severe and are found throughout the state. These masked night prowlers weigh 12-26 pounds and seek cover during the coldest weather, and like the true hibernators take on a thick layer of fat that is used to sustain it through short naps when frigid temperatures warrant inactivity.
Striped skunks are another well-known mammal and are constantly adapting to civilization. This misunderstood resident is as comfortable living under an urban back porch as it is in a burrow, brush pile, hollow log or abandoned structure.
By late autumn skunks develop a fat layer to use during the winter and females spend most of the winter in dens that are inhabited by six or more. Meanwhile, the males stay active, although, they too will den up during frigid weather and like bears are able to nap for a few weeks using stored fat reserves to fuel their body systems.
Our state mammal, the whitetail deer, is active year-round, as its unique hollow hair, filled with trapped air spaces, provides perfect insulation. With an excellent sense of smell and hearing, the whitetail has been able to avoid enemies and adapt to its constantly changing habitat.
Squirrels, foxes, porcupines, beavers, bobcats, cottontails and many other Pennsylvania mammals stay active throughout the winter. They spend a major portion of their time searching for food, so look for these mammals and signs such as tracks, droppings, remaining food bits and other indicators of their presence as they struggle to survive the winter.