Natives of Central and South America, opossums are not particularly well equipped for life in northern New England, and yet they have been found here in increasing numbers since about 1900. Unlike other fur-bearing mammals in the region, opossums have relatively thin coats, and their ears, tails, and feet are virtually hairless.
Besides lacking the proper outerwear, opossums do not hibernate. Except for denning up for short periods during the very coldest weather, they must be out and about all winter searching for food, which makes them extremely vulnerable to hypothermia and frostbite. In fact, wildlife biologists use signs of frostbite to judge an opossum’s age; a frostbitten tail and ears show that the animal has lived through at least one winter. This far north – central New Hampshire and Vermont and southern Maine mark the northernmost reaches of their eastern range – opossums rarely live more than two years, though they live much longer in warmer climates.
How, then, have they persisted in migrating northward?
Of the approximately 70 species of opossums, the one that became known as the Virginia opossum is the only one capable of storing fat under its skin and in its tail. The extra bit of fat – paltry compared to the amount of fat a raccoon puts on in the fall – enabled this species to move from Central into North America centuries ago. In the early 1600s, European settlers in Virginia encountered an abundance of these strange creatures, described by Captain John Smith as having “an Head like a Swine, and a taile like a Rat.” Even more marvelous, closer observation showed the opossum to be a marsupial, a mammal whose young are born quite small (A newborn opossum is about the size of a lima bean) and continue to develop in the mother’s abdominal pouch.
Beautifully suited to the climate of Virginia, North America’s only marsupial nevertheless continued to expand its range, until 300 years later it arrived in New England. Opossums have large families – between five and fifteen in a litter, with an average of eight – which helps explain its ability to colonize new areas.
Still, such an expansion would have been most unlikely except for the opossum’s ability to live near humans. Frequently called “an opportunist,” the omnivorous opossum can eat just about anything – from fruits, berries, insects, and small mammals to dog food left outside or garbage in dumpsters – and will happily make its bed under the back porch or in a corner of the woodshed. While its preferred habitat is in forested areas close to water, this animal’s close proximity to human habitation has been noted throughout the northern United States.
Unfortunately, we are most likely to see an opossum after it has been killed on the road. Nocturnal creatures, opossums rouse shortly after the sun sets and go out to look for food – often on roadways, where they feed on carrion and risk becoming roadkill themselves. According to studies summarized in Richard DeGraaf and Mariko Yamasaki’s New England Wildlife, human activities such as hunting, trapping, and roadkills account for the majority of opossum mortality. In one study, 35 percent of the animals equipped with radio transmitters or ear tags were killed by cars, while another 13 percent were killed in traps.
Fully grown, an opossum is approximately two and a half feet long, including the foot-long tail, and weighs from five to seven pounds. Encountering a predator or other threat, opossums may hiss and show their teeth but are more likely to run away and hide in a tree or burrow or to play dead. The tracker and naturalist Paul Rezendes describes an opossum he saw being attacked on the road by two dogs: “The opossum literally fell over, as if dropping dead of a heart attack. Saliva drooled from its mouth, and a very unpleasant smelling liquid began oozing from its anal glands. The dogs . . . barked at it, then nipped at it a few times, but the opossum didn’t move a hair.” After Rezendes chased the dogs away, the opossum got up and returned to the woods.
When out foraging or in its den – which can be in a hollow tree or brush pile as well as a human-made shelter – an opossum will be alone. Once the young leave their mothers, at about 120 days old, they are solitary animals and thus forgo even the comfort of snuggling up to another possum during the long, cold winter.
Catherine Tudish is a freelance writer living in Strafford, Vermont.