Virginia opossum

Physical Description and Unique Traits

The Virginia opossum is a robust animal with short legs and sharp claws, comparable in size to a domestic cat. Its fur is typically a dull grayish brown with a distinctive white face, long hairless ears, and a pointed snout. A key identifying feature is its long, hairless, prehensile tail, which is used for grasping branches. The opossum also has an opposable, clawless thumb on its rear feet, which aids in climbing and leaves a unique, splayed track. Perhaps its most remarkable physical trait is its dentition. With 50 teeth, it possesses more teeth than any other North American land mammal, including 10 upper incisors.

The species exhibits slight sexual dimorphism. Males are generally slightly larger than females, with average body lengths of about 40.8 centimetres compared to 40.6 centimetres for females. Tail lengths average 29.4 centimetres for males and 28.1 centimetres for females. Weight ranges differ as well, with males weighing between 2.1 and 2.8 kilograms and females between 1.9 and 2.1 kilograms. Their brain size is relatively small, having one of the lowest encephalization quotients among marsupials, with a brain only one fifth the size of a raccoon's.

The underfur of the Virginia opossum is usually whitish and tipped in black, though overall coloration can vary across its extensive range. Their feet feature an opposable hallux, or thumb, that works in conjunction with their sharp claws to make them adept climbers. The animal's tracks are distinctive, typically showing five finger like toes on both front and hind feet. The hind print is particularly unusual due to the opposable thumb, which often prints at an angle of 90 degrees or more relative to the other toes. Adult fore prints generally measure about 4.8 by 5.1 centimetres, while hind prints are larger at about 6.4 by 5.7 centimetres.

Range and Expansion into Canada

Its historical range before European settlement was limited to areas roughly as far north as Maryland, southern Ohio, Indiana, Illinois, Missouri, and Kansas. Over the last century, and particularly since 1900, its range has expanded dramatically northward and westward. This expansion is attributed to several factors, including forest clearing by settlers, the reduction of predator populations, and possibly warmer winters linked to climate change. In Canada, the opossum is now a regular resident in most of southern and eastern Ontario and has been recorded in extreme southwestern Quebec. Its range in the north now includes most of Michigan and Wisconsin, most of Minnesota, and southeastern South Dakota. Areas like the Waterloo Region and Simcoe County in Ontario, which rarely saw opossums in the 1960s, now report them regularly. The species was not native to the West Coast but was intentionally introduced there during the Great Depression, probably as a food source. From these introduced populations, it has been expanding steadily northward into British Columbia, with spread thought to occur naturally from populations in Washington State.

Some speculate that opossums initially entered Ontario by accidentally riding on motor vehicles or trains across major rivers like the St. Lawrence, Niagara, Detroit, and St. Clair. As the opossum is not well adapted to cold winters or heavy snow, its northern population levels can be significantly reduced by a severe winter season. The animal occupies a wide variety of habitats, from deserts to wet meadows, but shows a preference for woodlands and thickets near a water source, and can be found at elevations up to 3,000 metres. Small isolated populations also occur in areas like Eastern New Mexico and around Tucson, Arizona, though it is unknown if these are native or introduced.

Behaviour and Defence Mechanisms

The Virginia opossum is primarily nocturnal and solitary, most active between dusk and dawn. It does not hibernate but will significantly reduce its activity during severe winter cold, sometimes not leaving its den for several days if temperatures fall below minus 7 to minus 4 degrees Celsius. When threatened, an opossum's first reaction is often to flee. If cornered, it will attempt to appear threatening by baring its many teeth, snapping its jaw, hissing, drooling, and making its fur stand on end to look larger. This open mouthed hiss is often mistaken for a sign of rabies.

If these displays fail, the opossum may employ its famous tactic of feigning death, commonly known as 'playing possum'. In this state, the animal becomes limp and motionless, lying on its side with its mouth and eyes open, tongue hanging out, and feet clenched. Its heart rate drops by half, and its breathing becomes so slow and shallow it is hardly detectable. This behaviour, which can last for several hours, is intended to convince predators that the opossum is no longer a threat or viable prey. A foul smelling green fluid may also be released from its anal glands to further deter predators. Unfortunately, this instinctive response to oncoming traffic often results in the animal's death.

The opossum employs a distinctive pacing gait when walking. In this movement, the limbs on one side of the body move simultaneously, just before both limbs on the other side move. This results in left fore and right hind tracks generally being found together. Its stride while pacing typically measures from 18 to 25 centimetres. Other animals that commonly use a pacing gait include raccoons, bears, skunks, badgers, woodchucks, porcupines, and beavers. This gait and the unique hind track are useful for identifying opossum signs in the wild.

Diet and Ecological Role

Virginia opossums are opportunistic omnivores with a highly varied diet that changes with the seasons. Animal based foods form a significant part of their diet, particularly insects like grasshoppers, crickets, and beetles, which make up the bulk of their animal food intake. They also consume small invertebrates, earthworms, carrion, eggs, fish, amphibians, reptiles, birds, and small mammals such as young rabbits, voles, and mice. They are known to eat crayfish, gastropods, and are considered a common predator in poultry farming operations.

A common but scientifically unsubstantiated belief is that opossums eat thousands of ticks, thereby reducing tick borne illnesses like Lyme disease. A widely publicized 2009 laboratory study by the Cary Institute theorized they could eat thousands per week through grooming. However, studies of wild opossum stomach contents, including a 2021 study in Illinois, have not found any ticks in their diet. As of 2023, no scientific paper has reported ticks in the stomach contents of wild Virginia opossums, indicating the claim is likely a misconception.

Plant based foods become more important in late summer, autumn, and early winter. These include fruits like persimmons, which are a favourite, as well as raspberries, blackberries, apples, acorns, beechnuts, seeds, grains, bulbs, and vegetables. In urban and suburban areas, opossums readily scavenge from compost piles, garbage cans, pet food dishes, and bird feeders. Their attraction to roadside carrion, however, makes them highly vulnerable to vehicle collisions. The opossum possesses a unique resistance to snake venom due to special blood proteins like lethal toxin neutralizing factor, allowing it to prey on some venomous snakes. In captivity, such as at the Smithsonian's National Zoo, their diet can include fish, meat, eggs, pellets, fruits, vegetables, and mushrooms.

Reproduction and Life Cycle

The Virginia opossum has an extended breeding season that can run from as early as December through to October, with peak activity often in February and March. The season varies with latitude, and most young are born between February and June. A female may produce one to three litters per year, with those in warmer climates tending to have more. The mating season prompts behavioural changes. Males extend their range to search for mates, increasing their risk from vehicles and predators. Females carrying young forage earlier and later, raising their own risk levels.

The gestation period is remarkably short, lasting only 11 to 13 days. Litter sizes are large, averaging 8 to 9 infants, but can number over 20, with records of up to 25. The newborns are extremely underdeveloped, each about 14 millimetres long, the size of a honeybee. The mortality rate for these young is extremely high, with only about one in ten surviving to reproductive adulthood. As marsupials, opossums give birth through a median vagina or central birth canal. The newborns must immediately crawl from the birth canal into their mother's pouch, where they latch onto one of her 13 teats, arranged in a circle of 12 with one in the middle.

They remain attached in the pouch for about two months and are fully within it for two and a half months. The young are weaned after about 105 days but may begin eating solid food before that. After weaning, the young often ride on their mother's back for another couple of months as they learn survival skills before becoming independent at around four to five months of age. Both males and females reach sexual maturity within their first year. The female's reproductive system is bifid, with two lateral vaginae, uteri, and ovaries. The male's penis is also bifid, with two heads, and sperm pair up in the testes.

Lifespan, Threats, and Adaptations

Virginia opossums have unusually short lifespans for mammals of their size and metabolic rate. In the wild, they typically live only 1.5 to 2 years. Even under human care in captivity, their lifespan is usually only extended to about 3 or 4 years, with a maximum of around four years. This rapid senescence is thought to be an evolutionary adaptation to high predation pressure. With few natural defences, they were not under selective pressure to develop long term biochemical repair mechanisms for a long life, as their prospect of living long was historically low regardless.

An isolated population on Sapelo Island, Georgia, which has been without natural predators for thousands of years, was found by Dr. Steven Austad to have evolved lifespans up to 50 percent longer than mainland populations. The primary threat to opossums across their range is collision with motor vehicles. Their slow, nocturnal nature and their attraction to roadside carrion make opossums more likely to become roadkill. Furthermore, their instinct to feign death, or 'play possum', in response to threats from oncoming traffic often results in death.

They are also hunted and trapped for fur and food in some regions. Despite their adaptability, severe winters with heavy snow can significantly reduce northern populations, as they are not well adapted to such conditions. Opossums can host parasites and carry diseases such as tuberculosis, leptospirosis, and tularemia, though they are naturally highly resistant to rabies. Research indicates that living near humans can cause an increase in body size for opossums in urban environments. In captivity, opossums are known to engage in cannibalism, so placing an injured individual with healthy ones is not advised.

Relationship with Humans and Cultural History

Opossums frequently inhabit settled areas and are common in urban and suburban environments across North America, where they eat pet food, rotten fruit, and human garbage. They are generally not dangerous to humans. While their defensive hissing and bared teeth can be alarming, they are naturally resistant to rabies, though a few cases are reported annually. They are sometimes considered pests for raiding poultry, gardens, compost, and garbage. They are not closely related to rodents, despite sometimes being mistaken for rats.

The opossum has a rich history in American culture, particularly in the Southeast where it was once a popular game animal, featured in many traditional recipes found in older cookbooks like The Joy of Cooking. Preparation methods included baking, sometimes in a pie, though modern 'possum pie' usually refers to a sweet dessert. The animal was the subject of songs like the 1875 minstrel tune 'Carve dat Possum' by Sam Lucas. In animation and media, it has often been used to depict uncivilized characters or 'hillbillies', such as in episodes of The Beverly Hillbillies, including a 1965 'Possum Day' episode.

The title character in Walt Kelly's long running comic strip Pogo was an opossum. In an early 20th century merchandising attempt, President William Howard Taft was associated with the character Billy Possum, which failed to gain popularity. In December 2010, a cross eyed Virginia opossum named Heidi in the Leipzig Zoo in Germany gained international attention for predicting Oscar winners. Architecturally, a possum sculpture adorns the Perelman Building in Philadelphia, originally an insurance building, where it symbolizes 'protection'. Officially, the Virginia opossum was designated the state marsupial of North Carolina in 2013 and of New Hampshire in 2025.

Questions about Virginia opossum

Are Virginia opossums native to Canada?

Virginia opossums are not originally native to most of Canada. Their historic range was much farther south, generally no further north than Maryland and the southern Midwest before European settlement. They have expanded their range northward over the last century and are now established residents in southern and eastern Ontario and southwestern Quebec. Their presence in British Columbia is the result of a separate introduction to the U.S. West Coast during the Great Depression, from which populations have spread north naturally from Washington State.

Do opossums really eat thousands of ticks?

A widely circulated claim suggests opossums eat up to 5,000 ticks per season, acting as a natural control for Lyme disease. This idea originated from a 2009 laboratory study by the Cary Institute that theorized they could eat thousands per week through grooming. However, subsequent research on wild opossums, including a 2021 study examining stomach contents in Illinois, has not found any ticks in their diet. As of 2023, no scientific paper has reported ticks in the stomach contents of wild Virginia opossums, indicating the popular claim is not supported by evidence from their actual foraging.

What should I do if I see an opossum 'playing dead'?

If you encounter an opossum lying motionless with its mouth open and tongue out, it is likely feigning death as a fear response. The best action is to leave the animal alone and give it space. This behaviour normally stops once the perceived threat withdraws, and the opossum will recover and leave on its own, often within a few hours. Do not attempt to touch or move the animal, as this may prolong its stress or provoke a defensive reaction. The opossum may also release a putrid smelling green fluid from its anus as part of this defence.

How can I tell an opossum from a rat?

Opossums are much larger than rats, roughly the size of a house cat, with a robust body and short legs. They have a distinctive white face, long hairless ears, and a long, hairless prehensile tail. Rats have scaly, thinly haired tails and pointed snouts. Opossums are marsupials, not rodents, and are not closely related to rats or other placental mammals. Their tracks are also distinctive, showing five toes and an opposable thumb on the hind foot that prints at a wide angle. Opossums also have 50 teeth, far more than any rodent.

Are opossums a danger to pets or people?

Opossums are not typically aggressive and pose little direct danger to people or pets. They are solitary, nocturnal animals that usually prefer to flee or play dead when threatened. They are naturally resistant to rabies, though rare cases occur each year. They can carry other diseases such as tuberculosis, leptospirosis, and tularemia, and host parasites, so it is advisable to avoid direct contact. To minimize conflicts, secure pet food, garbage cans, and compost piles, as these attract opossums to yards. They are sometimes predators of poultry.

Why do opossums have such short lifespans?

The Virginia opossum has a maximal lifespan in the wild of only about two years. Their rapid senescence is thought to reflect the fact that they have few defences against predators. Given that they would have little prospect of living very long regardless, they are not under selective pressure to develop biochemical mechanisms to enable a long lifespan. In support of this hypothesis, one isolated population on Sapelo Island, Georgia, which has been without natural predators for thousands of years, was found to have evolved lifespans up to 50 percent longer than those of mainland populations.

Sources: Wikipedia and current public reporting, checked by the Your Space Hamilton desk. Last updated 2026-10-23.