Didelphis Virginiana: The North American Opossum

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Photo of an opossum searching for food

Opossums are the only marsupial species that can be found in North America. With the exception of the Rockies, Western Plains and parts of the Northern Region, they live in many parts of the United States.

Usually, opossums live alone and are active at night only. Though a relative of the kangaroo, opossums are much slower and when threatened, produce a nauseating smell. Because of their flexible diets and reproductive habits, these wild animals are able to survive in a wide range of conditions and locations.

The only species of opossums in North America is the Virginia opossum. Americans often refer to the Virginia opossum as “possum”.¹

Evolution Of The Opossum

The opossum is apart of the Didelphiade family. Didelphidae, representing 19 genera and 95 species, is the largest family of marsupials in the Americas and the only family in the order of Didelphimorphia. These animals include terrestrial, arboreal, scansorial, and semi-aquatic modes of locomotion that are quite diverse. ²

Although both the United States and Canada have found fossil remains of a smaller, closely related marsupial species, the Virginia opossum did not originate or evolve in North America. Instead, in South America, the direct ancestors of the Virginia opossum are thought to have evolved.

The landmass of North and South America was reunited during the Pliocene Epoch, between two and five million years ago, after being split for several million years. South America’s early marsupials evolved and diversified into a rich range of species during this period of separation. A single South American marsupial moved north as animals (Eutherian mammals) that had evolved in North America invaded South America. The marsupial continued to expand its range northward and diverged into what is now recognized as the Virginia opossum.

The Virginia opossum expanded its range into southern Canada and the Pacific States only during the last century. In the previous one hundred years, the ability of the opossum to expand its range to the Far West and northern regions of the United States and to southern Canada can be directly linked to the inadvertent or intentional intervention of humans. Since the colonialization of North America, the opossum has been able to expand its range considerably because of its adaptability to eat almost anything and create a den practically everywhere. ³

Characteristics Of The Opossum

For grasping and wrapping around stuff like tree limbs, a prehensile tail is adapted. For a short time, the opossum can hang from its tail. Some humans believe that opossums are hanging from their tails and sleeping. They don’t have tails strong enough to hold them for that long.

There is an opposable hallux in the opossum. Halluxs are large clawless toes operating like thumbs. When it climbs, the Hallux allows the Virginia opossum to grab branches.

In the winter, the opossum does not hibernate, but during freezing weather, it often holes up because it runs the risk of getting frostbite on its hairless tail, ears, and toes. ⁴

Opossum Reproduction Cycle

Image an possum climbing a tree

Within the first year of their life, Virginia opossums become sexually mature at about 6 months old for females and 8 months old for males but typically start producing babies around 10 months of age.

However, the exact months of the breeding season vary based on the location of an individual. This species has a long breeding season that lasts from February to September.

Based on the climate, the amount of litter per year varies. Virginia opossums average only one litter per year in northern regions, whereas the number of litters can increase to 3 per year in warmer climates.

4 to 25 altricial “honey bee-sized” young are born after an extremely brief gestation period of 12 to 13 days, although females usually have only 13 offspring, some of which may be non-functional.

The offspring weigh between 0.13 to 0.20 grams and are about 14 mm long in general. Although their newborn offspring are highly underdeveloped in many ways, the young do have muscular front legs, allowing them to climb to the mother’s pouch. ⁵

Life Span Of The Virginia Opossum

Opossums do not live very long; only about 1.5 to 2 years of wild opossums typically survive. Young opossums have a very high mortality rate early in life.

After birth, many of these altricial young animals never arrive in their mother’s pouch; about 60% of those who reach the pouch will die once they are weaned.

During the cold season, many adult opossums die. Female opossums may live slightly longer than males, but after 2 years of age, females are no longer able to birth young.

Typically, captive opossums live longer; they generally survive to be 3 to 4 years old; but there are reports of surviving captive Virginia opossums until they are 8 to 10 years old. ⁶

Opossum Typical Behavior

Essentially solitary, opossums avoid each other except in late winter during the breeding season. Generally, they are nocturnal and spend the day in hollow tree trunks, rock crevices, under piles of brush, or in burrows.

They are outstanding climbers and good swimmers. Opossums also spend a lot of time slowly crawling around on the ground, and they are often hit by cars as a result.

They have an excellent memory and a sensitive nose that allows them to discover where food is and remember it.

When facing danger, they “play possum,” entering a state similar to fainting that can last from less than a minute to six hours to make predators lose interest. ⁷

The Opossum Diet

Photo of a wildlife removal pro relocating an opossum

The opossum is an omnivore. A free-ranging possum diet ranges from plants, insects, garbage from garbage cans, and roadkill. The animal is an opportunist and will eat pretty much anything readily available.

Opossums are known to eat pests that humans try to avoid. They will eat snakes and are unaffected by the venom of rattlesnakes and pit vipers. The muscle tissue of the opossum has adapted to fight of venom and frostbite.

Opossums scavenge much of their food sources, allowing them to survive in most ecosystems. They are also drawn to roadkill (dead animals) and often get hurt while scavenging.

Top 10 Opossum Food Source

Plant Material
Worms and Insects
Grains
Fruits
Seeds and Bulbs
Carrion
Snails
Rats
Snakes
Crayfish

Habitats That Attract Opossums

Environments the opossum prefers are farmlands, wooded lowlands near water, and residential areas. The animal will only stay in one area if a constant food supply is available. They are creatures of habit and remember where in their habitat the food supply is located.

Temporary dens are provided by hollow tree holes and logs, the abandoned dens of other mammals; piles of rubbish, rocks, hay, and wood; storm sewers; and spaces beneath or within barns, sheds, houses, and abandoned buildings.

Human homes are often occupied by the possum due to the abundance of food supply and shelter. Pet food left outside of the home is a free meal for the animal and the possum will establish a den nearby to utilize that constant food source.

By collecting dry leaves or other plant debris with the mouth and front feet, the opossum may construct nests, then wrap the tail around the bedding material to carry it into a den. ⁸

References:

Pest World. (2020). Opossum Facts: Removal & Control of Opossums – PestWorld. Retrieved December 07, 2020, from https://www.pestworld.org/pest-guide/nuisance-wildlife/opossums/
Web, A. (2020). Critter Catalog. Retrieved December 07, 2020, from http://www.biokids.umich.edu/critters/Didelphidae/
PBS. (2020). Virginia Opossum – Didelphis virginiana – NatureWorks. Retrieved December 07, 2020, from https://nhpbs.org/natureworks/opossum.htm
Siciliano Martina, L. 2013. “Didelphis virginiana” (On-line), Animal Diversity Web. Accessed December 07, 2020 at https://animaldiversity.org/accounts/Didelphis_virginiana/
Paws. (2020). Opossums. Retrieved December 07, 2020, from https://www.paws.org/resources/opossums/
Communications, E. (2020). Opossum (Didelphis virginiana Kerr)Northern Flying Squirrel From: Saunders, D. A. 1988. Adirondack Mammals. State University of New York, College of Environmental Science and Forestry. 216pp. Retrieved December 07, 2020, from https://www.esf.edu/aec/adks/mammals/opossum.htm