Marmota monax
woodchuck

Woodchucks are found over east central Alaska and across southern Canada to the Pacific coastal provinces, extending south to northern Idaho. They are also distributed in the eastern United States (south to central Alabama and Arkansas)and westward to the edge of the plains.

As a result of deforestation and maintenance of the land of cultivated fields and pastures, the woodchuck has thrived and multiplied. Typical woodchuck habitat includes rolling farmland interspersed with grassy pastures, small woodlots, and brushy fencelines. Woodchucks especially prefer forest edges and openings though they are never far from cover, and they are partial to loam and sandy loam soils for burrowing. They have been found in a variety of forest types, including spruce and jack pine and cutover hardwoods.

The woodchuck is the largest sciurid in its geographic range. It has a heavy, chunky body (18 -26 in) set atop relatively short but powerful legs well adapted for digging. Males are slightly larger than females. The dark-colored, bushy tail is about one-fourth as long as the total body length, much shorter in comparison to other squirrels. Woodchuck skulls are broad and flat. Strongly developed supraorbital processes project at right angles from the frontals with the tips projecting slightly forward.

The dense, woolly underfur of the back and sides of the woodchuck is somewhat obscured by longer, less dense guard hair. These guard hairs are banded with alternating dark and light coloring (bands usually yellowish to reddish brown, hairs tipped with white), giving this mammal a frosted appearance. The underfur of the woodchuck is gray with yellow tips, much paler from the dorsal area. Ears are small, low and rounded atop a black-colored head with small black eyes.

There is one annual moult from late May to September, which begins at the tail and progresses forward.

The feet are black and slightly flattened. The hind foot has five well-developed digits. The rudimentary first digit of the forelimb is covered by a flat nail. All other digits terminate in curved claws that are useful in digging.

Woodchuck incisors are ever-growing and heavily constructed with the anterior faces ivory or yellowish ivory in color, lacking the dark yellow pigmentation of other rodents. If incisors are not worn down properly by occluding with the tooth opposite them in the course of chewing, they may continue to grow with often fatal results. Malocclusion of the incisors is frequently observed. The dental formula is 1/1 0/0 2/1 3/3.

The woodchuck also possesses three nipple-like anal glands, which secrete a musky odor.

Woodchucks can live up to six years in the wild, and ten years in captivity.

Woodchucks are the most solitary marmots although several individuals may share a single den. Woodchucks are usually highly agonistic. Though observed mostly on the ground, woodchucks have been seen climbing trees to reach food and swimming with only their head and nose above water. Woodchucks are considered diurnal in their aboveground activities, although they have been observed feeding in dim light or even at night, especially when food is scarce. In the spring and autumn, activity peaks near midday and late in the day. In the summer, the animal appears more active in the morning and afternoon, preferring clear and sunny skies for maximum activity. When not feeding, woodchucks sun, scratch, and preen themselves outside their den while watching for potential enemies. Woodchucks are very vocal mammals, hence the name "whistle-pig." When alarmed, a woodchuck gives a loud, shrill whistle. Teeth grinding and chattering are common when woodchucks are cornered. Woodchucks have also been heard to bark, squeal, and whistle when fighting with other woodchucks. When in danger, woodchucks retreat into nearby dens instead of running (when in motion, they usually walk though they can run at a loping gallop of about ten miles an hour). Predators include red foxes and humans; many other predators, such as the cougar, wolf, bobcat, or coyote have been extirpated or have experienced great reductions in their numbers in most areas.

Dens are situated in well-drained locations. With strong, clawed, forelimbs and large teeth, woodchucks can easily construct burrows with as many as five entrances. A plunge hole is often near the major den entrance and may have a vertical drop of as much as 2 ft to a main tunnel. These dens are also very long, up to 45 ft of tunnels, extending as far underground as 5 ft. Dens in open areas are used in the summer, and those under stumps, at the edge of rock ledges, and near other protection are generally occupied during the winter hibernation. Dens are always kept clean and well padded. Occupied dens can be recognized by a pile of fresh earth at the entrance. Nesting chambers are about fifteen inches in diameter and are usually sparsely lined with dry leaves.

Woodchucks are true hibernators, relying soley on body fat for winter survival. Hibernation takes place in a side chamber along one of the underground corridors of the burrow system. This prolonged topor reduces various metabolic processes- heartbeat slows (from more than 100 per minute to as few as 15), body temperature drops from about 35 degrees C to 8 degrees C, and respiration also decreases. While hibernating, the woodchuck rolls itself into a ball and tucks its head between its hind legs. Hibernation generally begins in October and ends in March or April (not on February 2). Hibernating chambers are thought to be located under the roots of trees. Woodchucks somehow seem to know when to wake up, controlled by a circannual clock, but actual emergence depends on the daily temperature.

Soon after leaving hibernation, sexually mature woodchucks begin the reproductive process. Males tend to venture above ground first and fight vigorously with each other. Woodchucks are not monogamous and males do not take part in raising the offspring. There is some evidence that woodchucks associate in groups which are dominated by a single adult male, discouraging other males from mating with his females.

Woodchucks can live up to six years in the wild, and ten years in captivity.

Woodchucks are very vocal mammals, hence the name "whistle-pig." When alarmed, a woodchuck gives a loud, shrill whistle. Teeth grinding and chattering are common when woodchucks are cornered. Woodchucks have also been heard to bark, squeal, and whistle when fighting with other woodchucks

Woodchucks are essentially herbivores, rarely eating insects, snails, and birds' eggs. They are primarily grazers, eating the vegetative parts of plants unlike other scuirids, which feed on reproductive parts such as seeds, nuts, and flowers. Woodchucks often sit on their haunches and pull plants over with their forepaws. In early spring, when green vegetation is sparse, woodchucks may eat the bark, buds, and twigs of plants such as dogwood, sumac, black cherry, and other fruit trees. Favorite foods include grasses and forbs, clover, leaves of sassafras and other trees, and numerous herbs. Woodchucks are also partial to farm crops especially alfalfa, planted clover, corn, oats, and assorted fruits and vegetables. Daily food consumption can be as much as 0.67kg.

Woodchucks use their burrows to escape from predators. They are preyed upon by large predators such as wolves, coyotes, and large hawks and owls. Their young are sometimes taken by snakes.

Woodchucks influence the how many and what kinds of plants there are in their communities by eating them. Woodchucks are also important and abundant food sources for many large predators in their communities.

Woodchucks are serious agricultural pests. Not only do they travel considerable distances to raid gardens, but their immense burrows damage farm machinery and destroy building foundations. Horses have been known to break their legs when stumbling into these burrows.

Woodchucks are favorite targets for sport hunting, which helps control their numbers. Their reproductive potential seems sufficient enough to prevent local extermination.

The burrowing activities of woodchucks often provide homes for many kinds of wildlife. Also, vegetation growth around burrows is enhanced by fertilization from buried fecal materials.

The woodchuck is often a subject of entertainment:

1. Outdoor antics of the woodchuck are entertaining to many animal watchers.
2. American folklore of Ground Hog's Day: the supposition is that when the woodchuck arised from hibernation on February 2 and sees its shadow, there will be six more weeks of winter.
3. Many movies have been made with woodchucks (or groundhogs) as the main characters such as both the "Caddyshack" films.
4. "How much wood would a woodchuck chuck if a woodchuck could chuck wood?"

As a result of deforestation and maintenance of the land of cultivated fields and pastures, the woodchuck has thrived and multiplied. Woodchucks are favorite targets for sport hunting, which helps control their numbers. Their ability to reproduce quickly is sufficient to prevent local extermination.