|[Note Guidelines] Photographer's Note|
|As I was shooting some birds, out came this ground hog for a drink in the river.|
The groundhog is the largest sciurid in its geographical range, typically measuring 40 to 65 cm (17 to 26 in) long (including a 15 cm tail) and weighing 2 to 4 kg (4.5 to 9 pounds). In areas with fewer natural predators and large quantities of alfalfa, groundhogs can grow to 80 cm (32 in) and 14 kg (30 lb). Groundhogs are well adapted for digging, with short but powerful limbs and curved, thick claws. The tail is only about one-fourth of body length, much shorter than that of other sciurids. Suited to their temperate habitat, groundhogs are covered with two coats of fur: a dense grey undercoat and a longer coat of banded guard hairs that gives the groundhog its distinctive "frosted" appearance. Groundhogs, like other sciurids, have exceptionally dense cerebral bones. These bones make them able to survive direct blows to the head that would cripple other mammals of the same body mass. The spinal structure of the groundhog is curved in a manner that resembles a mole rather than other sciurids.
Groundhogs hibernate in their winter burrows during the late fall and winter months. Their winter burrows are built in wooded areas to a depth of five feet, which is below the frost line and is at a stabil temperature well above freezing during the cold winter months. Groundhogs go into hibernation during October and emerge from hibernation during the months of March and April. To survive the winter, they are at their maximum weight shortly before commencing with hibernation. They emerge from hibernation with some remaining body fat to live off of until the warmer spring weather produces abundent plant materials for food sources.
Groundhogs usually live from two to three years, but can live up to six years in the wild, and ten years in captivity. Their diet consists of grasses, clover, Plantago, garden vegetables, leaves, twigs, apples, berries, and dandelion (Whitaker and Hamilton, 1998). They are not as omnivorous as many other sciurids, but will also eat grubs, grasshoppers, bugs, snails and other small animals.
Groundhogs are excellent burrowers, using burrows for sleeping, rearing young, and hibernating. The Wall Street Journal quotes wildlife expert Richard Thomas as calculating that the average groundhog moves approximately 1 m³ (35 cubic feet), or 320 kg (700 pounds), of dirt when digging a burrow. Though groundhogs are the most solitary of the marmots, the same burrow may be occupied by several individuals. Groundhog burrows generally have between two and five entrances, providing groundhogs their primary means of escape from predators. Burrows are particularly large, with up to 45 feet of tunnels buried up to 5 feet underground, and can pose a serious threat to agricultural and residential development by damaging farm machinery and even undermining building foundations.
Groundhogs prefer to flee from would-be predators, and usually retreat to their burrows when threatened; however, if the burrow is invaded, the groundhog will tenaciously defend itself with its two large incisors and front claws. Additionally, groundhogs are generally agonistic and territorial among their own species, and may skirmish to establish dominance.
Common predators for groundhogs include wolves, coyotes, bobcats, bears, large hawks, and owls. Young groundhogs are often at risk for predation by snakes, which easily enter the burrow.
Outside their burrow, individuals are alert when not actively feeding. It is common to see one or more nearly-motionless individuals standing erect on their hind feet watching for danger. When alarmed, they use a high-pitched whistle to warn the rest of the colony.
Usually groundhogs breed in their second year, but a small percentage may breed as yearlings. The breeding season extends from early March to middle or late April, following hibernation. A mated pair will remain in the same den throughout the 28-32 day gestation period. As birth of the young approaches in April or May, the male will leave the den. One litter is produced annually, usually containing 2-6 blind, hairless and helpless young. Young groundhogs are weaned and ready to seek their own dens at five to six weeks of age.
The groundhog prefers open country and the edges of woodland, and it is rarely far from a burrow entrance. Since the clearing of forests provided it with much more suitable habitat, the groundhog population is probably higher now than it was before the arrival of European settlers in North America. Groundhogs are often hunted for sport, which tends to control their numbers. However, their ability to reproduce quickly has tended to mitigate the depopulating effects of sport hunting. As a consequence, the groundhog is a familiar animal to many people in the United States and Canada.
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