Wildlife of Florida Factsheet: Virginia Opossum

The only marsupial north of Mexico

Breeding: spring, summer

Habitat: oak hammock, wetland, flatwoods, scrub, grasslands

Status: None

Scientific Name:

Common name: Virginia opossum, North American opossum, "possum"

Habitat: They prefer deciduous woodlands with streams and rivers but will use almost all terrestrial habitats available to them, including urban areas, agricultural lands, and wetlands.

Physical Description: Opossums are small to medium-sized marsupials with dark to grayish-white fur, a white, pointed face, and a long, hairless prehensile tail. They have opposable inner toes on their hind feet, a body length of 14–19 inches, and a tail length of 10–17 inches.

Weight: Adult weight varies widely across species range, with a trend for smaller individuals in southern populations. Average adult weight in Florida is 4 lb. The national average weight for an adult is 6 pounds for males and 4 pounds for females.

Reproductive Rate: Most females begin breeding in their second year. Those born late in the year may start breeding the following spring and can be as young as six months of age. They usually have one or two litters per year and an average of 7–8 young per litter. Gestation is a brief 13 days, and young are typically weaned at about 100 days. Most young are born between February and June, though breeding may continue through November.

Lifespan: Opossums have one of the shortest lifespans for a mammal their size. They live only 1–2 years in the wild and 3–4 years in captivity.

Dispersal and Home Range: Home ranges vary greatly in size and have been recorded as 10 to 350 acres. Females maintain significantly smaller home ranges than males. Opossums rarely disperse more than a mile from where they were born.

Biology and Behavior: Opossums are nocturnal and solitary, but their home ranges will often overlap and shift as they search for food. They are opportunistic omnivores whose diets consist of fruits, nuts, seeds, insects, worms, eggs, frogs, snakes, small mammals, carrion, human garbage, and the occasional farm chicken. Opossums are good climbers and can often be seen amongst tree limbs or straddling fences. Their balance and agility are aided by their long prehensile tails and the opposable inner toes on their hind feet. As commonly depicted, they can hang upside down from their tails, though adults are unable to sustain this position for long. Opossums do not dig burrows; instead, they take shelter in hollow logs, rockpiles, woodpiles, barns, abandoned buildings, burrows dug by gopher tortoises, and other species such as skunks, and even old squirrel nests. They may line their denning sites with leaves and debris, which they bundle up and carry with their tails. Opossums are an important prey species and have many predators, including coyotes, bobcats, raptors, snakes, and dogs. Opossums are known to make hissing, clicking, growling, and screeching vocalizations, and when threatened they will bear their teeth and vocalize aggressively. When opossums feel gravely threatened, they may respond by entering a catatonic state in which they lie stiff with their eyes open, drool saliva from their open mouths, and may defecate or excrete a putrid-smelling liquid from their anal glands. They may "play dead" for up to four hours.

Distribution: Opossums are found throughout Central America and much of North America east of the Rocky Mountains. They were introduced to the west coast of the United States around 1900 and can now be found throughout the Pacific coast from Baja California to southern British Columbia. Opossums do not thrive in extremely cold or arid climates, but they are continuing to expand their range north, likely aided by a combination of climate change and human intervention.

Did you know? Not only are opossums nearly immune to rabies, but they also have very strong resistance to venomous snakes such as water moccasins and rattlesnakes!

Unique Breeding: As their Latin name implies, opossum females have two uteri and a bifurcated (forked) vagina. (Didelphis virginiana: di means two and delphus means womb.) Males have a bifurcated penis and conjoined spermatozoa. Two sperm together have stronger motility while navigating the reproductive tract than does a single sperm. The joined sperm separate just before fertilization. This reproductive strategy is remarkably efficient; by comparison, opossums deploy 2% the number of sperm as rabbits, but the success rate of opossum sperm reaching the oviduct is 10 times higher than that of rabbit sperm.

Opossums are the only native marsupials in the continental United States, and like all marsupials, they give birth to relatively undeveloped young that continue to develop inside the mother's external pouch. At each birth, opossums typically deliver 10 to 25 young, each roughly the size and weight of a single honeybee. The newborns must crawl and attach to one of the mother's teats (females normally have 13), those unable to secure a nipple do not survive. The nipples then swell inside the newborns' mouths and anchor them in place for the next 60 days. Young are typically weaned at around 100 days and will increasingly leave the mother's pouch and often ride atop her back. By 150 days, the young will become independent and disperse.

Fast Facts:

• Opossums were once widely consumed as a game and furbearing species, especially in the southern United States.
• Opossums can live at elevations up to 9,000 feet above sea level.
• Opossums have 50 teeth, which is more than any other North American land mammal.

History: Virginia opossums are often erroneously called "living fossils" because their anatomy closely resembles their ancestral relatives from 70 million years ago. However, as a species, the Virginia opossum is believed to have diverged from the common opossum (D. marsupialis) of South America 75,000 years ago, making it the most recent species in the Didelphis genus.

Tips to Coexist:

• Secure your garbage bins and don't leave pet food outside.
• Drive carefully at night. Opossums are frequently struck by vehicles.
• Share what you have learned. Opossums are incredible, but they are widely misunderstood and have an undeserved reputation as being poor and lowly creatures.