Tuesday, August 30, 2016

The Awesome Possum of the Appalachians: Its Life Cycle and Natural History

(A Virginia Opossum in a cage trap before release.)
The Virginia Opossum (Didelphis virginianus) is a cat-sized, nocturnal marsupial native to most of the eastern U.S. and parts of California. It is a notorious scavenger, is relatively ugly and seeing one reminds some of an enormous, pale rat. The Algonquin tribe of northern Virginia called the opossum the "White Animal", due to its pale color. Still, most southerners, though stereotypically incorrect, despise the opossum because of its disgusting habits. First of all, the mother opossum basically gives birth to two sets of young. This extraordinary amount of baby opossums is drastically reduced even on the first few days of live, where the jelly bean sized baby marsupials make a journey from womb to a nipple on the side of the pouch. While opossums mature in the pouch, the mother may be hit by a car, resulting in the babies slowly starving to death. But after their eyes open, the young opossums begin to venture out of their mother's pouch and ride on her back. Many a baby opossum has been taken in by humans after it has unknowingly fallen from its mother's back. However, opossums that do mature do it extremely rapidly; in just a few weeks/months. Young, mature opossums are often a little bigger than a squirrel and they are fairly common. Once away from their mothers, young opossums may not find a denning site until they are full-sized. Until then, they will rest in hollows or crevices, but most famously, hang upside-down by their tail from a tree branch. Full-sized opossums do not have the flexibility to use their tail as their younger counterparts, so they must find a denning site. Opossums scavenge for varieties of food with an opportunistic manner. They will eat fruits (including normally poisonous horse nettle berries), insects, vegetable matter, fish, small mammals, reptiles, amphibians and, mainly, carrion, pet food and garbage. Their habits of stealing pet food and rummaging through and sleeping in trash cans makes them very unpopular to some. Opossums do kill over four thousand ticks in a week due to the way they groom themselves. When opossums encounter a venomous snake or spider, they can eat it because they have an immunity to venomous bites. One main source of food for an opossum is roadkill, easy to find carrion. Whenever a raccoon,  deer, or fox is hit by a vehicle, the vulture is replaced by the opossum at night. This leads to the opossum's fame of being roadkill itself; opossums do not learn to adapt to roads like coyotes and cats do. Another reason it is hit by a car is because besides just being slow, it has a unique defense mechanism. If a predator such as a coyote or bobcat approaches an opossum and is seen, the opossum will run a short distance and stop. If it is pursued it will look its attacker in the eyes with its mouth open slightly and it will hiss. This behavior, as a matter of fact, gained it a nickname, "grinner". The reason it does this is for intimidation. An opossum's teeth are long, fang-like and sharp. If that's not enough, the opossum's teeth are often coated in extremely deadly and infectious bacteria due to the rotting carrion they are designed to tear apart. And to top it off, the Virginia Opossum has more teeth (fifty) than any other animal in North America!
(This adult Virginia Opossum is in the process of "grinning" before release.)
So a few predatory species will be deterred by this, but if one predator attacks the opossum it will feign death, or in other words; "play possum". It does this by opening its mouth, hanging out its tongue and drooling, falling on its side, and oozing a green, decay-scented fluid from its anal glands. But when an opossum manages to complete a successful roadkill harvest, it may have eaten a rabid animal; for that is one of the most common causes for death by vehicle to wildlife. Roughly all but about 5% of opossums have a gene that gives them a blood flow just cold enough that the rabies virus cannot affect them. As far as an opossum's home goes, it may be a rock crevice, hollow tree, an abandoned burrow, or often even the attic of a house, giving the opossum an even worse name. Opossum tracks are often found in the mud near chicken coops, sheds, barns, garages, springhouses and other outbuildings.
(An opossum track in mud behind a leak in the back of a stagnant pond.)
Another fun fact about opossums is that their feet are like hands. Their feet have no fur, and barely any hair, are pink, and have claws arranged like long, sharp fingernails. Their back feet, in fact, have an opposable thumb used for holding onto objects and climbing. Opossums come out soon after dark, and they are quite easy to catch with practice. If you approach a wild opossum, it will most likely turn around and run. You need to catch up or block it so it will freeze. Then you can either grab its tail without getting bitten and hold it upside-down by its tail so it cannot bite you, or provoke it until it plays dead. Catching opossums often leads to the question about the classic hillbilly/possum connections. The long and short of it is that the folks that the typical "Beverly Hillbillies" stereotype portrays didn't really eat opossums unless it was a certain occasion when they were starving, or more often, an adventurous young raccoon hunter who decided to eat an opossum he had shot. However, it was said that during the Great Depression, eastern travelers to California brought caged opossums over as a food source and they still exist there today. But of course, that theory has not and cannot really be proven. Another interesting fact is that on Roan Mountain, another species of opossum, the Southern Common Opossum (Didelphis marsupialis)  has been recorded on one of Tuttle's species surveys of the area. The name "Common Opossum" may have incorrectly been given to the undeniably native Virginia Opossum, as what most likely happened, because the Common Opossum reaches its most northern range into mid-Mexico. So now, I hope no matter how much you despise or appreciate opossums, you learned at least something new about our own "Awesome Opossum". Happy Trails, Critter Cade
(A young opossum, just after release from a cage trap.)