Opossum Joeys, Didelphis virginiana

Opossum: Biology, Life Cycle and Habitat

America’s only marsupial tends to have a bad reputation. Perhaps, it’s the opossum’s appearance and nocturnal lifestyle that makes this creature so unappealing. After all, spotting a large rat-like creature with beady eyes and a scavenger’s appetite in a beam of light is just plain creepy.

  Do Opossums Benefit The Environment?

Surprisingly, the answer is yes. Compared to other types of wildlife, they are very helpful. Opossums not only play an essential role in the ecosystem, but they can also be a valuable asset to your garden, in spite of the fact that most people are quick to control their numbers.

Opossums, sometimes called possum, benefits your garden by ridding it of small insects and pests. As omnivores, opossums consume a variety of foods. This includes the beetles, slugs, and snails which damage garden plants.

These nocturnal creatures also consume plant matter. In general, the opossum prefers fallen or rotting vegetation to fresh. Cleaning up dropped fruits and vegetables, which can harbor disease, is another benefit to having these creatures around.

  Appearance

Opossum
Didelphis virginiana
Lifespan 4 years
Weight 6-12 pounds
Length (without tail) Males: 32 inches
Females: 28 inches
Color Gray in color, though
their coats may vary
from red to brown.
Activity Mostly nocturnal.
Sexual Maturity 6-7 months
Gestation Period   11-13 days
Litter Size 1-20 Joeys
(about ½ survive)
Adult Predators Owls, hawks, red foxes,
cats, dogs

There are actually 60 species of opossums, with the species Virginia opossum being native to Wisconsin. This is actually the only marsupial, meaning pouched animal that is found in Canada and the United States.

Opossums have sharp claws that help them dig into the bark of trees while climbing. They also have a long gripping tail which they use as an additional limb during climbing. The rear limbs have clawless, opposable thumbs. These prehensile tails are hairless. Possums have hairless ears and a pink nose at the end of their flat, long snout.

Opossums can vary greatly in size. The average one will be around the same size of an average house cat, but they tend to be smaller in the tropical areas and larger farther north. Their fur is usually gray but it can be anywhere from black to brown to white due to variations in their guard hairs. These guard hairs can also vary in thickness.

Their mouth holds the most teeth of any mammal in North America — 50.

  Life Cycle

Opossum Nest
Opossum Nest

Although a litter of opossums may have up to 20 joeys, less than half of these animals will survive on average. When opossums are born, they are as small as honeybees and completely helpless. Joeys will crawl into their mother’s pouch immediately, which is where they develop and stay safe. Not all of the newborn opossums will make it this far. Eventually, the possums get larger and occasionally leave their pouch. They will also ride on their mother’s back while she goes out in search of food.

  Habitat

You can find the Virginia opossum throughout North America and Central America to the east of the Rockies. They span from southern Ontario to Costa Rica and are expanding their range north.

Possums tend to live by or in wooded areas, particularly those that are close to water. They are also frequently found in urban areas. Since they are excellent climbers, it is not uncommon for possums to nest inside of tree holes. They can also frequently be found in dens that were previously made by different animals.

Opossums don’t build shelters themselves so you can find them in old buildings or sheds as well or in fallen logs, hollow trees, and cavities in brush piles or rocks. They will bring nesting material to their chosen shelter.

  Diet

Opossum Eating Fruit
Opossum Eating Fruit

Possums are scavengers, which means they will eat whatever food they can find. Because of this, they will frequently be found by human homes, raiding dumpsters and garbage cans. Opossums will also carrion, which is why you will frequently find them by roadkill. Additionally, these animals eat fruit, nuts, and grass. As omnivores, they also hunt birds, mice, worms, insects, and snakes as well as chickens.

Possums have a relatively small brain, but are able to find food as well as remember where they found it. In fact, opossums scored better than cats, rats, rabbits, and dogs in some tests for their memory. They can also remember how toxic or noxious substances taste.

  Behavior

Opossum Playing Dead
Opossum Playing Dead

Perhaps the most common possum behavior is 'playing possum.' This is their defensive mechanism that naturally occurs when they are threatened by a predator, such as a bobcat, fox, or dog. They will flop on their sides then lie on the ground. Their eyes will either be closed or they will stare into space with a fixed view. At the same time, these marsupials extend their tongues to complete the impression that they are dead. This has proven to be an effective way to put predators of guard and give the animals the chance to escape.

Possums are not typically aggressive, but they do have a defensive posture when threatened. If cornered, they will either sit back or crouch down and open their mouth. This displays as many of their teeth as possible. This action is accompanied by screeches or growls that tend to get more intense.

Opossums are also great climbers, spending a great deal of their time in trees. Their biology helps with their climbing capabilities. If caught and then handled, possums will frequently defecate and the glands by the base of their tail will release a secretion that is pea-green. Possums are mostly nocturnal, typically foraging after dark. When it gets colder out, such as during winter, they are more likely to be active during the day since they need to eat more.

  Mating and Reproduction

Opossum Mating
Opossum Mating

The breeding season for the Virginia opossum can begin as early as December and continue through October with most infants born between the months of February and June. A female opossum may have 1-3 litters per year. During the mating season, the male attracts the female by making clicking sounds with his mouth.

Eleven to thirteen days after mating over 20 infants may be born, although an average litter consists of 8-9 infants. The infants are so small at birth that 20 could fit into a teaspoon. Each of the hairless, embryonic-looking “pinkies”. At birth, the infants must make a long and difficult journey from the birth canal into the pouch, latch onto a teat, and continue their development. The mother helps by licking the hair leading into the pouch, providing a moist path for the infants to follow.

The young remain in the pouch for about 2 1/2 months and at around 55-70 days the eyes open. As they become too large to fit in the pouch, they climb onto the mother’s back and are carried as she searches for food.

Further Reading:

 Beavers — Nature's Hydrologist
 Garter Snakes — The Gardener's Friend
 Wisconsin Native Salamanders
 Goundhog or Woochuck: All The Facts
 Voles, Both The Good and The Bad

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