The Virginia Opossum (Didelphis virginiana)

 

Cute, pretty, and adorable are words often used to describe many of Virginia’s wild mammals, but not so for the Virginia Opossum (Didelphis virginiana). In a popularity survey, this animal would likely rank near the bottom of the list, below the skunk.  Given its low standing, the opossum has little to lose from my attempt to boost its ratings by sharing a few characteristics that make this animal so unique.  Inspired by the words of Baba Dioum “In the end we will conserve only what we love, we will love only what we understand, and we will understand only what we are taught,” I thought I would give it a try.   

Let’s start at the beginning.  According to the Opossum Society, yes, that’s a real organization, the opossum’s ancestor existed 70 to 90 million years ago, during the time dinosaurs roamed the earth. While the dinosaurs are now extinct, the opossum has survived, having evolved into its present form around 75,000 years ago.   Our first written record of the opossum in Virginia comes from Captain John Smith of the Virginia Colony in 1608.   Captain John Smith referred to the animal by its Powhatan name “apasum" (Algonquian language) when he described the animal as “An Opossum hath an head like a Swine, and a taile like a Rat, and is the bigness of a Cat. Under her belly she hath a bagge, wherein shee lodgeth, carrieth and sucketh her young.” 

Master Naturalists should note that the names “opossum” and “possum” are not interchangeable. Opossums are a group of marsupials that live in the Americas, whereas Possums are a different group of marsupials, which all live in Australia and New Guinea. There are two marsupials found in North America. The southern opossum (Didelphis marsupialis) is a species that lives primarily in Mexico, whereas the Virginia opossum (Didelphis virginiana) is found primarily in the eastern United States, although its habitat is expanding.  In additional to being a marsupial, the opossum has many interesting features. It has 50 teeth, more than any North American land mammal, but the shortest life span of any mammal its size at just 2 years. Opossums have a long narrow snout, pink nose and bare ears. Because their ears and tails lack fur, they can suffer frostbite.  Their hairless tail is prehensile and is used for grasping branches, balancing and carrying nesting material, but not for hanging upside down as commonly believed.  Let’s examine a few other common myths about the opossum.

Myth #1. Opossums eat snakes, even venomous snakes.   This is true.  Opossums are resistant to the venom of most snakes, including rattlesnakes, copperheads, and cottonmouths.   Scientists have successfully isolated the peptide strand in the blood of the opossum that counter acts venom.  This could one-day lead to a universal anti-venom that could revolutionize the treatment for snake bites. However, opossums do not actively hunt snakes, but rather as opportunists will eat small snakes if encountered. Opossums must avoid large snakes, less they become the prey.

Myth #2. Opossums cannot get rabies.  This is False.  Any mammal can get rabies, but it’s extremely rare for an opossum. It’s believed that their low body temperature, between 94 and 97 degrees, may inhibit the rabies virus by making it difficult for it to survive. While there are a few reports each year of opossums with rabies, cases in bats, raccoons, skunks and foxes are far more prevalent. Since it is possible to contract other diseases from an opossum, always keep a safe distance, even if the opossum is dead or perhaps playing possum.  

Myth #3.  Opossums play “possum” as a natural defense mechanism.  This is true.  When an opossum is threatened, it will first show its teeth and hiss like a house cat. If that fails to scare off the predator, the opossum may climb a tree. When it becomes extremely afraid, the opossum will “play possum” through an involuntary defense mechanism where it enters a catatonic state, making itself appear dead, and therefore less appealing to its predators.  Upon entering a catatonic state, opossums roll over, become stiff, bare their teeth, and secrete foul-smelling fluid. The catatonic state is more common in young opossums and can last from minutes up to several hours. Unfortunately, opossums have no control over when this happens and if frighten by headlights of an approaching vehicle, it may play possum at just the wrong time.  

Opossums are omnivorous scavengers. They eat insects like cockroaches, crickets, beetles, and love snails and slugs.  The menu continues with rotting fruit, earthworms, bird eggs including poultry eggs, amphibians, mice, pet food, and kitchen scraps in compost bins.    Fortunately for humans, opossums also eat any tick that attaches to them, including ticks that cause lyme disease and rocky mountain spotted fever.   However, the main component of their diet is carrion. More opossums are killed by vehicles while scavenging for carcasses along roadside than are killed by predators like dogs, owls, coyotes, foxes, and bobcats.  A female is more prone to be killed on the road than a male because she moves slower due to the extra weight added by babies in her pouch or on her back. 

The survival of the opossum may be due in part to their reproduction. Reaching reproductive maturity as early as 6 months, the female called Jill will often raise two litters in a year in Virginia.  After a 13-day gestation period, Jill gives birth to a litter containing 4 to 25 bee-size babies called joeys. Joeys crawl from the birth canal into its mother's pouch and latch onto one of her 13 teats, where they remain attached for about 55 days. Infants in excess of 13 do not survive, however, rarely do 13 joeys reach the pouch anyway.  Until they are about 85 days old, the young either travel in their mother’s pouch or on her back. An evolutionary difference between opossums and most other mammals is that the mother opossum never has to return to a den to feed her young, since they are always traveling with her.   The young are weaned at approximately 100 days old and leave their mother and siblings to become the solitary scavenger they are meant to become.    The combination of early reproduction and large litters helps to insure the opossum’s survival. 

Joey, a young Virginia Opossum (Didelphis virginiana) Photo by Ed Coleman

Still not convinced you want an opossum around.  Well, if you want to discourage the Virginia Opossum from visiting your yard, there are a few things you can do to deny access to food and a den site.  Do not leave pet food outside overnight, remove spilled bird seed from below feeders, secure garbage can lids tightly,  enclose compost bins, remove fallen fruit from the ground including persimmons,  remove brush, prevent entry to the underside of decks, porches, and outbuildings, ensure siding and attic vents are intact, and fasten the crawlspace door and chicken coop. 
    
Sources:
https://www.treehugger.com/things-you-didnt-know-about-opossums-4864240
https://www.ncwildlife.org/Portals/0/Learning/documents/Profiles/Mammals/Opossum_Wildlife_Profile_UPDATE.pdf

https://www.nps.gov/neri/learn/nature/virginia-opossum.htm

https://www.wildlifeillinois.org/gallery/mammals/looks-like-a-dog/opossum/

https://nationalzoo.si.edu/animals/virginia-opossum

https://kids.sandiegozoo.org/animals/virginia-opossum

https://opossumsocietyus.org/

http://www.wildliferesponse.org/component/k2/item/57-virginia-opossum