Groundhogs (Marmota Monax) are the largest rodents in this area. Groundhogs are mainly vegetarian, but will also eat grubs and insects. A member of the marmot family, groundhogs are great at burrowing and can excavate up to 50 feet of tunnels; these can be as deep as 5 feet with several entrances and different levels. While the deepest parts of the burrow are used for hibernating, parts of groundhog burrows used in summer are typically shallower and easier to enter and leave.

Groundhogs keep a tidy burrow, replacing nesting materials frequently. The average weight of an adult is about 7 to 12 pounds, with exceptionally large groundhogs attaining over 30 pounds in weight. They are 16 to 20 inches long plus a short tail of 4 to 6 inches, with females slightly smaller than males. Their lifespan in the wild is 4 to 6 years. Groundhogs are brown with chisel-like incisor teeth and short, powerful legs with sturdy claws for digging.

In February in this area groundhogs start venturing out sporadically to seek mates. Males establish dominance over territories and visit the burrows of females in their area in late winter, looking for mates. Mating is instinctively timed to provide the young with the best chances for survival. Early mating would result in a litter being born before a plant food supply is readily available, while late mating would not give newborn animals enough time to put on weight to get them through winter hibernation.

Groundhogs have one litter per year. They typically mate soon after hibernation ends, during March to early April, producing a litter of 2 to 6 hairless, blind young after a one month gestation period. Solitary animals, and not monogamous, the males usually part the female burrow after mating. The females care for the young until they are weaned in about a month and a half, and then drive the young out of the nest to fend for themselves. Groundhogs usually feed within 50 to 150 yards of their burrows. In areas of plentiful food, such as crop fields, they may remain with in 25 yards of their burrows.

In the fall groundhogs prepare winter burrow nests in which they hibernate until spring. Groundhogs, like most mammalian hibernators, gradually drift into hibernation and then gradually drift out of hibernation, going through this cycle of deep hibernation and near wakefulness a dozen or more times during the winter. Similar to other hibernators, groundhog body temperatures drop in deep hibernation to just above the temperature of the winter burrow, as low as 40 degrees. Groundhog heart rates drop from about 80 while active to around 5 beats per minute in hibernation. In late winter body temperatures gradually elevate while coming out of hibernation as they receive nutrients from stored body fat.

The burrows can undermine building foundations and can be a danger to livestock. Groundhogs also are good at eating garden produce and crops, and are difficult to control. For small garden areas fencing of 3 to 4 feet above ground can help keep them out, with the base buried a foot underground and the bottom part of the fence bent outwards at a 90 degree angle. Various smelly substances sprinkled on the garden can also help repel them, including epsom salts and rags soaked in ammonia, castor oil, peanut oil or olive oil, all of which need to be replenished. For larger areas, removing the critters is the best control method. Removal can involve use of non-lethal live trapping and relocation. Pouring sudsy ammonia down their holes encourages them to find a new location, with the abandoned holes filled in to prevent re-use. Lethal control methods include smoke devices sold at agricultural supply stores.

Adult groundhogs have few predators in our area, due to their size. Young animals can be captured by foxes, hawks, racoons, coyotes and domestic canines. They are not considered a danger to humans or pets, but become aggressive and can bite and scratch when cornered. While appearing fuzzy and slow, it is best to avoid direct contact as they can also carry rabies in addition to their powerful claws and jaws. Usually a groundhog is quick to retreat to its burrow when approached.

The animals are referred to by different regional names, including woodchucks, marmots and whistle pigs (from a shrill sounds they can make when danger is present). The origin of the commonly used term woodchuck doesn't have anything to do with wood, but is thought to be based on the Algonquian Indian word for the animal, wuchak.

Article by FCFCDB

Nature Note for 7/20/14