The shy opossum is a superhero in secret (What’s in your backyard)
By DAVID WASMUTH
For Montclair Local
The opossum deserves more respect.
Its direct ancestors roamed the earth with the dinosaurs, surviving both Tyrannosaurus rex and that fateful asteroid. Confined to present-day South America and Australia for millions of years, it was along for the ride when South America split off and drifted into Panama.
It then crossed into North America to become the only marsupial north of the Rio Grande. This survivor of the Dinosaur Age now resides in your Montclair, New Jersey, backyard.
It’s not just their history as living fossils that makes opossums special. While I have yet to see any dressed in capes and tights, they have what can reasonably be described as a superpower: opossums are immune to snake venom.
While other mammals shy away from rattlesnakes and copperheads, opossums are happy to munch on them for midnight snacks. Their unusually low body temperature also makes them resistant to rabies.
And opossums are champions in the fight against Lyme disease. Ticks are among their favorite treats; according to one estimate, an opossum can eat up to 5,000 per season.
But if opossums are superheroes, they carry their mild-mannered Clark Kent-like disguise to extremes. Ungainly outside of trees, their maximum amble speed is around 4 miles an hour. While I find their appearance cute in a quirky East-Village-in-the-’80s way, many other humans find their looks less than charming. Their long tails are often described as “rat-like” and their eyes as beady. Their spiky fur is a nondescript grayish-white, and then there is that cone-shaped snout ending in pink nostrils.
Maybe not appealing to our sensibilities, but we must assume the look is attractive to other opossums. Not that they can see each other well; opossums have both poor eyesight and poor hearing. They rely more on acute senses of smell and touch.
Opossums have other unique qualities. With 52 teeth, they hold the record for a North American mammal. Their tails can grasp tree branches, helping make them agile climbers. Reports of them hanging upside down by their tails are disputed but may be true of some lightweight juveniles.
They share with humans the rare feature of opposable thumbs but, in another sign of originality, they wear these thumbs on their hind paws.
What most distinguishes the opossum in North America is that, as a marsupial, it’s as close as we come to having a native kangaroo. Opossums breed twice a year, once in late February or March and once in May or June. After a gestation period of only about 12 days, a litter of blind, hairless babies, each around the size of a bumblebee, emerges.
The tiny newborns use their surprisingly well-developed front limbs to do a kind of crawl stroke through their mother’s fur to her pouch. Once inside, each attaches itself to a nipple and remains attached for about three months, growing to the size of a mouse.
At this point it detaches and begins moving to and fro from the pouch, enjoying rides with its siblings on the mother’s back. By four months, the young stop nursing and begin foraging for food on their own. Thereafter, they are largely solitary and grow to about the size of a large house cat.
There is some dubious folklore about opossums — for example, females do not give birth through their nostrils — but one odd tale is true. The original pacifist, the opossum’s typical reaction when cornered by a potential predator is not to fight back but to “play ’possum.” It goes limp, hangs out its tongue, and gives off an odor of putrefaction — all in all, very unappetizing to most predators, who prefer live prey. The opossum can remain in this state for up to four hours, until the danger has passed.
Opossums are shy, nocturnal animals and make unobtrusive neighbors. They shelter from bad weather in hollow logs, tree cavities and rock crevices. They might be found under porches but, unlike raccoons or squirrels, will not break into closed spaces. They don’t dig their own burrows but will make use of the abandoned burrows of other animals, personalizing the space with leaves carried in by tail.
Adaptable omnivores, opossums thrive in the suburbs. Besides the snakes and ticks mentioned above, their natural diet includes insects, earthworms, small mammals, birds’ eggs, toads, carrion, berries, grasses and acorns. Suburban Montclair provides supplements in the form of garbage, compost, pet food and road kill.
They will feed some from vegetable gardens, but prefer fallen, rotted vegetables. Any damage to the harvest should be weighed against the benefits opossums provide, for snails and slugs are among their favorite foods.
Opossums lived in the South for most of their stay in North America, slowly expanding their range over the centuries and probably reaching northern New Jersey in the 16th century.
With the warming climate, their northward expansion has accelerated. In recent decades they have moved as far north as Vermont, southern Ontario and even Michigan’s Upper Peninsula.
Still, they are ill-equipped for winter cold. They put on fat for insulation but do not grow a winter coat. Frostbite often costs them ears, toes and the tips of their tails.
So, in spite of their superpowers, opossums are short-lived. In the face of winter cold and predators such as foxes, dogs, coyotes and cars, they rarely survive for more than two years.
Consider: It’s a species as old as the dinosaurs. An intrepid migrant from South America to Canada, it faces winter chill while dressed for the tropics. Impervious to snakebite, it eats thousands of Lyme-transmitting ticks per year. It carries its young, kangaroo-like, in a pouch. It might even be considered the originator of nonviolent resistance. And it lives in your backyard.
In “What’s in Your Backyard,” Sanford Sorkin and David Wasmuth alternate writing about the birds and beasts you may see around your house. Wasmuth is a local environmentalist and amateur naturalist. He is a Rutgers Environmental Steward and the founder of the Montclair Backyard Habitat Project. Seen a bird or animal you want to know more about? Write to us at firstname.lastname@example.org.