Tracks
Virginia opossum tracks generally show five finger-like toes in both the fore and hind prints.[12] The hind tracks are unusual and distinctive due to the opossum's opposable thumb, which generally prints at an angle of 90° or greater to the other fingers (sometimes near 180°). Individual adult tracks generally measure 1.9 in long by 2.0 in wide (4.8 × 5.1 cm) for the fore prints and 2.5 in long by 2.3 in wide (6.4 × 5.7 cm) for the hind prints. Opossums have claws on all fingers fore and hind except on the two thumbs (in the photograph, claw marks show as small holes just beyond the tip of each finger); these generally show in the tracks. In a soft medium, such as the mud in this photograph, the foot pads clearly show (these are the deep, darker areas where the fingers and toes meet the rest of the hand or foot, which have been filled with plant debris by wind due to the advanced age of the tracks).
The tracks in the photograph were made while the opossum was walking with its typical pacing gait. The four aligned toes on the hind print show the approximate direction of travel.
In a pacing gait, the limbs on one side of the body are moved simultaneously, just prior to moving both limbs on the other side of the body. This is illustrated in the pacing diagram, which explains why the left-fore and right-hind tracks are generally found together (and vice versa). However, if the opossum were not walking (but running, for example), the prints would fall in a different pattern. Other animals that generally employ a pacing gait are raccoons, bears, skunks, badgers, woodchucks, porcupines, and beavers.
When pacing, the opossum's 'stride' generally measures from 7 to 10 in, or 18 to 25 cm (in the pacing diagram the stride is 8.5 in, where one grid square is equal to 1 in2). To determine the stride of a pacing gait, measure from the tip (just beyond the fingers or toes in the direction of travel, disregarding claw marks) of one set of fore/hind tracks to the tip of the next set. By taking careful stride and track-size measurements, one can usually determine what species of animal created a set of tracks, even when individual track details are vague or obscured.
Behavior
The Virginia opossum is noted for reacting to threats by feigning death. This is the genesis of the term "playing possum", which means pretending to be dead or injured with intent to deceive. In the case of the opossum, the reaction seems to be involuntary, and to be triggered by extreme fear. It should not be taken as an indication of docility, for under serious threat, an opossum will respond ferociously, hissing, screeching, and showing its teeth, but with enough stimulation, the opossum will enter a near coma, It lies on its side, mouth and eyes open, tongue hanging out, emitting a green fluid from its anus whose putrid odor repels predators. Heart rate drops by half, and breathing rate is slowed by about 30%. Brain activity is unaltered however, and the animal remains fully conscious. Death feigning normally stops when the threat withdraws, and it can last up to six hours. Besides discouraging animals that eat live prey, playing possum also convinces some large animals that the opossum is no threat to their young.
Opossums are omnivorous and eat a wide range of plants and animals such as fruits, grains, insects, snails, earthworms, carrion, snakes, mice, and other small animals. The Virginia opossum has been found to be very resistant to snake venom.[13] Persimmons are one of the opossum's favorite foods during the autumn.[14] Opossums in captivity are known to engage in cannibalism, though this is probably uncommon in the wild.[15] Placing an injured opossum in a confined space with its healthy counterparts is inadvisable.
The Virginia opossum does not hibernate, although it may remain sheltered during cold spells.[16]