Do you say possum or opossum? The fact is, in Michigan, we have the North American
Opossum ( Didelphis virginiana) , also known as the Virginia Opossum. We do not have possum. Possum refers to a group of about 70 small to medium sized arboreal marsupial species native to Australia, New Guinea, and Sulawesi. However, many people use the common name possum to refer to opossum. Honestly, that’s one of the reasons I chose to write this article. Opossum are one of our most common yet least understood mammals. In addition to being called by the wrong name, some people see opossum as an ugly, scary pest with a menacing grin full of teeth. Like most animals, the more we learn about them, the less scary they become. Setting aside our prejudices, we are able to appreciate this beneficial and interesting critter strolling through our yards in the moonlight.
The opossum is North America’s only marsupial. Marsupials are born incompletely developed
and are carried and suckled in a pouch on their mother's belly. In some cases, 20 to 50
opossum have been born in a single litter, but as the mother only has 13 teats, any additional
offspring may not survive due to lack of nutrition. An average litter will yield eight or nine
offspring. Baby opossum, called “joeys”, reside in their mother’s pouch for the first
two-and-a-half months before climbing onto her back. After about four or five months the joeys will leave the mother.
Some people find opossum cute, while others find them to be hideous. Famous for their startling grin of 50 teeth, the opossum have more teeth than any other land mammal in North America. They may have a mouthful of teeth, but opossum do not have much of a brain. Surprisingly small for the animal’s size, the brain of an opossum is about one-fifth the size of a raccoon's brain. The lifespan for opossum is very short, lasting only about two years in the wild. Even in captivity, opossum only live about four years on average. Living outside their native range, the opossum’s wiry body hair and hairless tails are not sufficient adaptations to survive our frigid climate in northern Michigan.
Ever since European settlers began clearing dense forests in the region, the range for opossum
has been expanding northward at a significant pace. Oceana County is north of the native range of opossum. The pre-European settlement range extended as far north as southern Ohio,
Indiana, and Illinois. Since 1900, reports exist of opossum thriving throughout Michigan.
However, living outside of their native range does present some challenges. Michigan winters
are harsh for the opossum, and it is not uncommon for them to lose parts of their ears or tails to frostbite. Their thin, wiry hair is not sufficient insulation against our frigid winter temperatures.
Cursed with a reputation as chicken killers and garbage raiders, the opossum has a surprisingly
diverse diet. Opossum are omnivores, eating a mixture of plants and animals such as fruits,
grains, insects, snails, slugs, eggs, mice, rats, fish, frogs, snakes and carrion. Acting as
groundskeepers, opossum consume many undesirable pests. A single opossum can consume
as many as 4,000 ticks per week, significantly reducing the threat of lyme disease. They also
are known to eat cockroaches, rats, and mice. Opossum are mostly immune to rabies and are
resistant to snake venom allowing them to prey on snakes. Although they have been found
invading trash cans, or raiding chicken coops, the presence of opossum can be more of a
benefit than a burdon. Securing trash cans and eliminating entry points into chicken coops will
limit their negative impacts.
When frightened or harmed, opossum suddenly freeze and lie still as if dead. They have no control over this response, which could be said to paralyze them with fear or have evolved
because almost any predator can outrun them. If left unharmed, a catatonic opossum will
recover in roughly one to four hours. When confronted, opossum may display their teeth
and even hiss. However, rather than fighting, this shy and inoffensive adversary utilizes a
survival strategy of entering a state of apparent death. The opossum’s lips draw back, teeth
bared and saliva foams around the mouth. Eyes are half-closed and a foul smelling secretion is
emitted from the anal glands. An opossum in this state can be prodded and even carried without awakening, but we strongly recommend respectfully leaving them alone.
Orphaned opossum are sometimes taken as pets despite being illegal to keep them without a
wildlife rehabilitation permit. These are wild animals with a short lifespan and they can become
sick from the stress of captivity. Professionals at zoos and wildlife rehabilitation centers are
trained to properly care for wild animals. Opossum at these facilities can be used as educational animals to teach adults and children about wildlife rehabilitation and conservation. Learning about our local marsupial allows us to understand the role of opossum in the ecosystem, and convinces us to dispel any feelings of disgust or contempt for these surprisingly beneficial creatures.