About the Virginia Opossum, a yard’s ideal visitor


Always be kind to Virginia Opossums. They’re docile, sweet-tempered and totally non-aggressive. They have a wicked hiss and a mouthful of teeth they like to flash when threatened, but they don’t bite, except in self-defense. And, they never have rabies.

Virginia Opossums are ideal and visitors to urban yards. They’re quiet, they don’t dig or claw. They don’t eat flowers or chew up the vegetable garden. Instead, they arrive, eat a rodent and some snails, scoop up some insects, munch on fallen fruit and clean up any leftovers in the dog food bowl. Then they go away. DFW Wildlife Coalition calls them “vital groundskeepers,” for their beneficial role in helping to control garden pests, and other foraging habits. HGTV calls them the “Garden’s nightly clean-up crew.”

Virginia Opossums have existed since the Pliocene Epoch, two to five million years ago.¹ They’ve endured the passage of time astonishingly well, and largely unchanged. How? Scientists don’t know for sure, but think it’s probably because they’re masters of adaptation: Change their habitat, they adjust to a new one. Remove their usual food sources, they change their diet.

There are more than 60 species of opossums (oh-POSS-ums) in the world, but the Virginia Opossum is the only one that inhabits North America. It was first seen by European colonists in, yes, Virginia.

Opossums are marsupials, mammals that undergo the early part of their development in their mother’s womb and the rest of it in her pouch. Other marsupials include kangaroos, koalas, wombats, wallabies, Tasmanian Devils and…possums. That isn’t a misprint. Opossums aren’t possums! Except for being marsupials, possums are a group of entirely different animals, in the family Phalangeridae. They inhabit Australia and surrounding islands.

Virginia opossum, Didelphis virginiana, clinging to a tree trunk.

Opossum. (ksblack99 / Flickr; PD)

Brushtail_Possum, Trichosurus vulpecula.

Possum. (Andrew Mercer / wiki; cc by-sa 4.0)

The earliest marsupial species evolved in North America and moved south to South America. The direct ancestors of the Virginia Opossum evolved later in South America and moved north to the southeastern U.S. During the late 1920s and the 1930s they were introduced into western coastal states and have now expanded northward into southern British Columbia. They also extend south into Mexico and Central America, where most of the other opossum species are found.

Virginia Opossums, Didelphis virginiana, are in the order Didelphimorphia and the family Didelphidae. Their genus name Didelphis is Ancient Greek for “double womb.” As you read on, you’ll see how appropriate that name is. “Opossum,” comes from apasum, an Algonquin Indian word for “white animal.”

Physical characteristics
Virginia Opossums are 2 to 3 feet (61 to 91 cm) long, plus a tail length of 8 to 13 (20 to 33 cm) inches. Sources vary widely about their weight, with some reporting a range of 4.6 to 6.2 pounds (2.1 to 2.8 kg) and others as high as 8.8 to 13.2 pounds (4 to 6 kg). Males are usually larger than females.

Black-and-white drawing of an opossum skeleton.

Opossum skeleton. (ZooKeys / T.E. Williamson, Stephen L. Brusatte, Gregory P. Wilson; cc by 3.0)

Virginia Opossums have a long, pointed face with black eyes, long whiskers and a distinctive pink nose. Their ears are black and tipped or edged with white, and hairless. White hair covers their face, and their body is a sparse, coarse mix of grayish and blackish hair. Their thin hair makes them susceptible to frostbite, preventing them from inhabiting regions that are too cold.

Virginia Opossums have 50 teeth, the most of any U.S. land mammal. When they open their mouth, all those teeth are exposed and look truly menacing. That’s deceptive because opossums are mild-mannered unless deliberately provoked; sometimes not even then. If you’re in doubt, watch this.

Close up of a Virginia Opossum's tail.

Virginia Opossum’s tail. (Lisa Wright / EOL; cc by-nc-sa 3.0

Their tail is hairless, scaly-looking and long. It’s prehensile, which means it can be used to hold or grasp things. You may have heard that opossums sleep while hanging by their tail, but that isn’t so — they’re too heavy to hang for very long. In fact, holding them that way is painful for them.

Opossum feet. (Phil Myers / EOL; cc by-nc-sa 3.0)

Their feet are bare on the bottom. They have five hairless, dexterous toes (some experts call them fingers). Each of the hind feet has a thumb, called a hallux. All their toes are clawed except for the thumbs, which are used to grasp branches when climbing.

Uniquely odorless: Virginia Opossums have no body odor because they lick themselves constantly. The licking, at least in part, has to do with thermoregulation of their body temperature — they lack sweat glands and the evaporating saliva helps to cool them.

Virginia Opossums have a keen sense of touch. Their sense of smell is exceptional — they have 1,188 genes devoted to smell. (By comparison, humans have 396 olfactory genes devoted to smell and dogs have 811.²) Their eyesight is poor, however, and their senses of hearing and taste are rather weak, too.

Virginia Opossums make only a few distinct vocalizations. They hiss, snarl, click and screech, and may make all of these sounds when showing aggression. Clicking is also made by males in mating behavior and by females when around their young. Young ones also make clicking sounds. Some sources say mothers make a purring sound to their young. Listen to baby making clicking sounds.

Opossums have a reputation for being dim-witted because they move slowly and have a small brain size (five times smaller than a raccoon’s). However, researchers found in a series of tests that opossums are better than dogs, cats and other animals at remembering the location of food hidden in a maze; only humans were superior to them. And, owners of young rescued and un-releasable opossums say they can be litter box- and leash-trained, love to be held and to snuggle, and will greet them at the door when they return home. They also claim that opossums will come when their name is called.³

Young Virginia Opossum, Didelphis virginiana, facing the camera with mouth wide open and hissing.

Opossums try to seem very dangerous, by flashing their teeth and hissing — even young ones, like this. (rgrichie, iNaturalist / EOL; cc by-nc 4.0)

Virginia Opossums are solitary, except when mating or caring for young. They’re strictly nocturnal, except in winter when they’re sometimes active in the daytime on warm days. Many people have seen them only as roadkill or in the spotlight of a suddenly-switched-on porch light. Coming face-to-face, opossums may freeze in place, but often they just turn and move away. For them, movement is usually a shuffling, clumsy-looking waddle, but if circumstances compel them, they can run at about 4 miles per hour — equivalent to a fast walk for a human. They know this isn’t fast enough to save them from most predators, so typically they head for safety. They might crawl into a den, scale a tree (they’re expert at this) or swim (they’re able swimmers). Or they may drop “dead.”

Opossum lying on its side pretending to be dead.

Opossum playing possum. (Tony Alter / Flickr; cc by 2.0)

Playing possom: Virginia Opossums are well-known for pretending to be dead, or “playing possum,” but that isn’t playing for them. Feigning death is apparently an involuntary, stress-induced nervous collapse, and it’s convincing: They fall on their side and lie still with their body curled. Their mouth opens in a grimace, their tongue hangs out, they drool copiously and stare with unmoving eyes. They may defecate or discharge a foul-smelling fluid from their anal glands. They don’t respond to sound or prodding. They’re pretty persuasive and oftentimes predators that don’t eat dead meat will move on. This catatonia-like state may last minutes or hours. Eventually, they arouse, get up and go about their activities with no ill-effects. If they’re frightened again after awakening, they may play dead again.

They don’t always play dead, however. Instead, they may try to bluff their way out of trouble with a flash of teeth and scary hissing and snarling. But, they’re aggressive only if necessary. 

Females reach sexual maturity at about seven months of age and can breed about every 28 days year-round. Peak time is late December through January (February in northern areas), and to a lesser extent from mid-May to early-July. After mating, males go their own way and don’t participate in raising the young.

Opossum baby clinging to its mother's back.

Opossum baby on mother’s back. (E Nava / Flickr; cc by 2.0)

Females typically mate only one or two times a year, each time having 8 to 12 young. Their reproductive system is bifid, meaning there are two sets of reproductive organs. (The male’s penis is also bifid). Some of the fetuses develop in a left uterus and the others in a right uterus. But, like cars merging into a single traffic lane, the fetuses are born one by one through a birth canal called the median vagina. They have a very short gestation period — only 12 or 13 days. After their birth, the young continue their development in their mother’s pouch (marsupium).

But first, they must perform a harrowing journey to get there. The newborns weigh 1/200th of an ounce — the size of a bee. Hairless and nearly transparent, they aren’t much more than embryos. Mothers prepare the way by licking a path through their hair for them to follow. With a swimming motion, the babies pull themselves blindly (literally, since their eyes are closed) along this path. The trek is only three or four inches, but for these little guys, it’s monumental. Treacherous, too. A sudden move by their mother and they’ll fall off and perish. The weaker babies will not make it, regardless.

Those who make it to the fur-lined marsupium will find one of 13 teats aligned there in a horseshoe arrangement. This is their lifeline to further physical development and they hang on tightly. If there are more than 13 babies, the extra ones will die.

Two months later and the size of a mouse, babies have begun to outgrow their warm, protected environment that’s now stretched nearly to its limit. Ever so cautiously, they peek out. Then they duck back inside. They peek out. They duck back inside. They’ll do this many times over the next couple of weeks until finally they climb out — still clinging to their teat! They’ll stretch just as far as they possibly can, but won’t turn loose.

Eventually, in a tense moment of bravery, they open their mouths and let go. Then comes the second significant climb of their lives: up to their mother’s back (not her tail, contrary to myth), where they tightly grasp her hair with their toes and tail. If any fall off, they make hissing sounds, and their mother makes clicking sounds in response. If she’s unaware they’re gone, however, she’ll go on without them, and at this young age, they’ll perish.

Virginia Opossum, Didelphis virginiana, with numerous youngsters clinging to her back.

Opossum mom. (Specialjake / Wiki; cc by-sa 3.0)

Those on her back are about to go for the ride of their life. They travel widely in search of food, staying in one den only three or four days before moving to the next (except in winter when a nice, warm, well-built nest invites a longer stay.) Their mother will use her whiskers like a cat, to feel her way along dark passages, and her excellent sense of smell will locate food. They learn the best ways to hide and defend themselves, and where to live.

They go up and down trees, through thick bushes and brush piles, into garbage cans and compost piles, under the porch, under fences, through drain pipes and culverts, and into hollow logs. They might even go into the water if their mother crosses a creek. All the while, they must tightly hang on.

After a few weeks of tutoring, they begin life on their own four feet by simply loosening their grip and dropping off their mother. By now, they’re about seven to nine inches long, excluding their tail. They share their mother’s den for a short time, then leave to establish their own territories.

Captive Virginia Opossums can live up to 10 years, but those in the wild usually don’t make it past their first year, because of heavy predation and vehicles.

Although well adapted to city life, their natural habitat is deciduous forests, but they also are found in farmlands, prairies and wet areas, such as marshes and streams.

Food sources
You name it, they’ll eat it, and that’s probably a factor in their survival since prehistoric times. In addition to “people food” in the garbage can and pet foods left outdoors, opossums eat insects, fruits, grains, nuts, rodents, frogs, the eggs and young of other animals and carrion.

Cover and nesting
The opossums are solitary animals that generally nest alone. Females, however, will sometimes use daytime nests together.

Opossums’ feet are soft and delicate with small claws, not designed for digging. So, they look for existing nest sites that will keep them warm and safe, such as old burrows, drainage pipes, hollow logs, old squirrel nests, rock piles, woodpiles or under a porch. Even a chimney. They line nests with soft, dry materials, like grasses and dried leaves. They gather their nesting materials by mouth and then shove them under their body, where they loop their tail around them for transport.

Natural enemies of opossums include foxes, coyotes, bobcats, eagles, owls and other birds of prey; also dogs and cats. Otherwise, vehicles are their biggest enemy. It’s thought that opossums’ willingness to eat carrion draws them to roadkill and then, frequently, they become roadkill. Hunters and trappers, too, take a toll, but mostly by finding opossums while seeking other game.

Opossums and rabies
The body temperature of opossums is 94 to 97 ºF (33 to 36 °C), which is too low for the rabies virus to survive. It’s nearly impossible for an opossum to catch rabies.

*Top photo: Lisa Wright / EOL; cc by-nc-sa 3.0

Related reading:
¹Ancient origins of modern opossums revealed
²For the curious: African Elephants have the best sense of smell, with 1,948 olfactory genes. See the Top-10 list
³ Wildlife cute, but not good pets  
Quick bits: Rabbits and hares of N.A.