2010-07-17 / Columnists

Woodchucks Are Largest Squirrels in Great Lakes Region

Nature Notes
By Patricia Martin

“How much wood could a woodchuck chuck if a woodchuck could chuck wood?” This old rhyme came to me when earlier this summer I got a call from a young friend, who stepped outside of his cottage and heard a great ruckus coming from the barn. When he reached the barn, he discovered that his two Jack Russell terriers had cornered a woodchuck and the poor creature was literally climbing the walls. It found precarious safety on a board part way up the wall and was staying put. My friend called off the dogs, putting them in the house. When he returned to the barn, the woodchuck had made its escape.

Woodchucks (Marmota monax) are also known as groundhogs and, because of the high shrill whistling sound they make when they’re frightened, they’re sometimes called “whistle pigs.” Now, I understand calling them groundhogs, as they live in the ground, but woodchucks, unlike their much larger cousin, the beaver, they have little to do with wood.

Woodchucks are by far the largest squirrels in the Great Lakes region, weighing in at five to 11 pounds (the one my friend saw may outweigh his Russells, he said). They have a chunky body set on short, strong legs, which are great at digging. Their front legs have four toes with slightly curved claws, which help in excavation. Adult woodchucks are usually about two feet long, with the tail making up about a quarter of that length. They are much smaller, proportionally, than our other squirrels. The tail is dark colored and the guard hairs along the back are yellowish to reddish brown with a white tip, giving the woodchuck a frosted look. The ears are rounded and low and the feet are black. Albino and melanistic (black) woodchucks are not uncommon. They have the typical rodent teeth, with a pair of powerful, curved, sharp incisors on the upper and lower jaw, but unlike most of the rodents, the fronts of these teeth are not orange or yellow but white.

Before human habitation, woodchucks would usually live in open forests. In fact, the first one I saw on Mackinac was in the woods between Fort Holmes and Point Lookout quite a number of years ago. These rodents have adapted to people and now are found in rolling farmland, grassy pastures, small wood lots, and brushy fence lines. On Mackinac I’ve seen them near the seeps just beyond Arch Rock, and have had reports of them living under someone’s porch. In North America, woodchucks range from Alabama to Labrador, all the way to Alaska.

Normally this ground squirrel likes to dig a burrow in welldrained soil, usually in a bank or hillside. The entrance to the den is usually surrounded by a 10- to 12-inch mound, which leads to a tunnel that starts by sloping upward to prevent water from coming in. Often the woodchuck will dig another hole, a “plunge hole” that drops about two feet straight into its underground den. There is usually a back door, which is much more hidden than the front, often covered by vegetation. The underground tunnels may extend 20 to 30 feet in length, with an enlarged nesting chamber filled with dry leaves. These squirrels may excavate several burrows in a season. The woodchucks keep their dens clean, burying their feces in small pits and covering them with soil. Old or unused dens are used by skunks and rabbits for their own homes.

Woodchucks are active during the day, leaving their dens to hunt for food. They are basically vegetarians, enjoying grasses and other plants such as daisies, goldenrod, and clovers, but they will also raid your garden for carrots, beans, celery, and corn. In the spring, when such vegetation is scarce, these rodents will eat the tender parts (bark, buds, and twigs) of dogwood, sumac, and cherry.

Unlike most of their cousins, woodchucks do not store their food for the winter, as much of their preferred food does not store well. In fact, they don’t have to create a cache of food, as for the most part, they sleep away the winter. These squirrels are true hibernators, with the ability to drop their body temperature to about 40 degrees Fahrenheit and maintain it for months at a time with only brief periodic arousals. This ability to reduce the body temperature reduces the body’s metabolism and therefore reduces the need for energy. Woodchucks begin their hibernation in October and come out of it in March or April. They are usually sound asleep on Groundhog Day (February 2). To be able to maintain this long hibernation, the woodchuck has to pack on the pounds in the summer and fall because by spring, they will lose about onethird of their body mass.

The male woodchuck, in the spring, ventures forth to find a mate. Though generally diurnal, the males may wander around at night during the mating season. The males fight vigorously with one another for dominance. Several weeks later the females emerge out of hibernation and mate almost as soon as they come out. Yearling females mate later than adult females. About a month after mating, two to five young are born, each weighing in at less than an ounce. About six weeks after birth, the young are weaned and soon after, they disperse. It is not until the end of their second summer before they’re at full body weight, although they are sexually mature at the beginning of their second spring.

Woodchucks have been known to survive for six years, although most only make it to their third. When young and small, they are prey for hawks, fox, bear, lynx, and bobcat, although as adults their size is something of a deterrent. Humans have also hunted them for food and to get rid of what some farmers see as an agricultural pest, and some are hit by vehicles along the highways, something that woodchucks living on the Island don’t have to worry about.

Trish Martin is a year-around resident of Mackinac Island, has earned a master’s degree in botany from Central Michigan University, and owns Bogan Lane Inn.

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