An adult opossum is about the same size as a house cat, but with much shorter legs. Total length ranges from 24 to 33 inches. Adults weigh from 6 to 15 pounds. Males are usually larger than females. The opossum has a narrow, tapered head with a pointed muzzle, pink nose, black eyes and bluish-black ears that lack hair and look leathery. The long, scaly tail is black near the base and fades to a yellowish white or pale pink about one fourth of the way to the tip. Both the front and hind feet have five white or pink toes. The inner toe of each hind foot is clawless and thumb-like. The dense, woolly underfur of most opossums is creamy white with grayish tips.
The long outer hairs are dark gray or black. This combination gives most opossums a grizzled gray appearance. A few are almost black while others are very pale gray or nearly white.
Distribution & Abundance
Opossums are common and found throughout Illinois. They tend to be most abundant in the southern part of the state, especially along the Wabash, Mississippi and Ohio rivers. High numbers also occur in some urban areas. Populations can exceed 200 opossums per square mile in favorable habitats. On a seasonal basis, numbers are lowest in late winter. They peak in midsummer with the influx of young from second litters.
Wooded areas near streams provide good habitat. Farm fields mixed with patches of woods tend to support more opossums than large expanses of forest or cropland. Opossums prefer areas near permanent water such as ponds, lakes, swamps, streams and rivers. They seek shelter in the dens or nests of other animals, sheds or old buildings, cavities in rocks, brush piles, trash heaps, dry culverts, hollow trees and fallen logs. They sometimes line their dens with leaves, grass or corn husks.
Opossums are slow, secretive and solitary. They venture from their dens at night to look for food, traveling distances of 1/2 to 2 miles depending on food availability and the time of year. They're observed frequently in the glare of automobile headlights as they eat other animals killed by traffic (and often suffer the same fate).
Opossums tend to wander a great deal and shift their home sites frequently, but most spend their lives in an area 10 to 50 acres in size. Opossums do not hibernate, but stay denned up during extremely cold weather. Opossums are well adapted for climbing. The opposable toe on the hind foot acts like a thumb, allowing them to grasp small branches. An opossum can hang by its tail for a short time if at least half of the tail encircles a thick branch.
Opossums often climb trees or hide in brush heaps when chased. They are well known for "playing 'possum". When frightened and unable to escape, an opossum rolls over on its side, becomes limp, closes its eyes and lets its tongue hang out of its mouth. The heartbeat slows down and the animal looks dead, causing many would-be predators to lose interest. This reaction is caused by a nervous shock, but the opossum recovers quickly and takes the first opportunity to escape.
Opossums are omnivorous (eat both plant and animal matter) and not very finicky. The animal portion of its diet often includes insects, dead animals, birds and their eggs, frogs, snails and earthworms. They also eat fruits and berries, especially during fall and early winter. Corn is an important part of their diet during winter. Bird food and leftovers thrown out with the trash are common fare in urban areas.
Opossums reach sexual maturity at about one year of age. The breeding season begins in early February. Most females have one litter per year, but some have two. First litters usually arrive in late February; young from a second litter are born in late July
Hunting and trapping are regulated by the Illinois Department of Natural Resources to keep populations from declining and make sure that young and mothers are protected. Few people try to improve habitat specifically for opossums because they're abundant and adapt easily to a wide range of habitat conditions. Measures that maintain woodlots, fencerows and hardwood forests are beneficial, as are forestry practices that leave some old trees uncut during logging operations.