OMG there are at least seven. There is the mommy and six babies, at least, that Ruby_Red_Robin and I saw. They were so cute! They're actually more in Ruby's yard than mine, or maybe their actual den is in between. Well, there's this HUGE bush that we THINK they live in. Ruby gave them really weird names I think the names are stupid. They're like... Bo-Bo and Patchy and Tinny and other weird stuff. The only good one is Tinny. But I spell it Tinni 'cuz I think it's a girl. I'm making a book about them, I'll show you it when I finish!
That's cool. We used to have a lot of rabbits in our backyard last year... they reproduce like crazy. We even saw their babies, and I left a carrot out for them, but they didn't touch it.
I will try my best to get down to the hard-core facts ...
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.
A nearly-motionless individual, alert to danger, will whistle when alarmed to warn other groundhogs.
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.
Groundhogs feed on a variety of plants such as grass, clover, Plantago, and berries.
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.
Groundhogs raised in captivity can be socialized relatively easily; however, their aggressive nature can pose problems. Doug Schwartz, a zookeeper and groundhog trainer at the Staten Island Zoo, has been quoted as saying "They’re known for their aggression, so you’re starting from a hard place. Their natural impulse is to kill ’em all and let God sort ’em out. You have to work to produce the sweet and cuddly."