The opossum is an agile climber and good swimmer. Adults weigh 4–11 pounds and measure approximately 2–3 feet in length, including a long hairless tail. It uses its prehensile (grasping) tail to stabilize itself as it walks along tree branches. The hind feet have an opposable big toe that functions much like a human thumb. Opossums are an overall grizzled white color with a pink nose, large black hairless ears with pink tips, and short dark legs. They have 50 teeth, more than any other land mammal on this continent, which they may bare when threatened. Opossums have the smallest brain to weight ratio of any North American mammal; regardless, they are an incredibly adaptable species that has been able to thrive in North America.
Opossums are solitary animals except when coming together to mate or when females have young. Opossums breed from January to July. After about 2 weeks, they give birth to a litter of 1–13 kits. Kits are born blind and hairless without well-developed rear limbs. Immediately after birth, young crawl into their mother’s pouch and nurse for 8 weeks. Young will then ride on their mother’s back for 4 weeks and will become fully independent at 12 weeks. Opossums become sexually mature at 8–12 months of age and typically have 1 litter per year.
Opossums can be found in open woods and farmlands next to water, as well as suburban and urban areas. They are mostly nocturnal but are sometimes seen in daylight, especially when food is scarce. Opossums are nomadic and tend to not den in the same area for consecutive nights. They den in abandoned burrows, tree cavities, hollow logs, and brush piles.They remain active year round and do not hibernate. Massachusetts is near the northern end of the opossum’s geographic range and as a result they can have difficulty dealing with the cold temperatures experienced here. For this reason, opossums often use homes, sheds, garages, and other buildings as refuges from the cold. It is also not uncommon to see the signs of frostbite on an opossum’s furless ears, nose, and tail.
Their primary foods include eggs, grains, nuts, fruit, birds, snakes, frogs, mice, and carrion (dead animals). Opossums will also take advantage of human associated foods, such as garbage, pet food, bird seed, corn, and poultry. Because they eat many road-killed animals, they often become road kill themselves. Opossums are also preyed upon by owls, raptors, bobcats, coyotes, and unsupervised dogs. When opossums are threatened, they will growl, hiss, and bare their teeth or climb a nearby tree to escape. If they are unable to escape, the opossum will play dead for several minutes to several hours until it believes the danger has passed.