Hibernation – a state of inactivity, metabolic depression and lowered body temperature adopted by certain mammals as an adaptation to adverse winter conditions (cold temperature and decreased access to food). The true hibernator spends most of the winter in a state close to death, with a body temperature close to 0° C (32° F) and respiration rate of only a few breaths per minute. Bears and a few other mammals spend most of the winter sleeping in dens, but do not undergo much lowering of body temperature and are rather easily awakened, so they are not considered true hibernators.
Groundhogs are also known as Woodchucks.
The name Woodchuck has nothing to do with wood. One thought is that it may be derived from the Native American words wejack, woodshaw, or woodchoock. Another possibility is that their name came from the English settlers attempt at saying the Algonquin word for these animals, “wuchak”.
Groundhogs are true hibernators. During hibernation their body temperature lowers to around 37° F, their heart rate decreases to 4 beats per minute, and their respiratory rate can be just one breath per minute.
Although they are most often seen on the ground, Groundhogs can climb trees and are capable swimmers.
A Groundhog’s den, or burrow, consists of a series of tunnels which can be up to 25 to 30 feet long and from 2 to 5 feet deep. There is usually one main entrance, but also other openings that can be used for escape. They have separate tunnels for hibernation, rearing their young and for going to the bathroom.
Other animals often use a Groundhog’s burrow for cover, to keep cool and even for hibernation.