By Anne Blackburn
Chair, Riderwood Wildlife Habitat Management Project (WHMP)
Opossums are the only marsupials (pouched mammals) living in North America. We know some are on campus because several years ago Riderwood allowed baby opossums, whose mother had been hit by a car, to be released here.
Long on the planet, they have accumulated impressive characteristics. They are largely free of rabies and are immune to the poisonous bites of rattlesnakes and cottonmouths. Their prehensile tails allow them to hang from branches for a short time and to gather and carry small bunches of grass. They have opposable “thumbs” on their hind feet which make them excellent tree climbers. Just after birth, the tiny babies (the size of honeybees) climb into their mother’s pouch and stay for two to three months. After that their mother will carry the little ones on her back when she goes looking for food. They normally live only two to four years, and because they move so slowly, they are vulnerable to dogs, cats, foxes, and other animals, and moving vehicles as well.
But it is opossums’ defense mechanisms that are especially impressive. When threatened they will hiss, bare their teeth, growl, and foam at the mouth. Their apparent disease discourages many predators. If those actions do not work, they may fall into a catatonic state that can last for up to four hours — once again warding off predators who prefer not to consume diseased prey. This “playing dead” happens automatically; it is comparable to fainting by people.
These pointy-nosed, rat-tailed creatures may not be handsome but they provide useful services to humans. They eat ticks, which are carriers of the troublesome Lyme disease. Some researchers estimate that a single opossum can consume up to 5000 ticks in a season. They also clean the forest floor, eating fallen fruit, snails, slugs, worms, carrion, and plants. Their excellent sense of smell makes them good at finding food and even better than either dogs or cats at remembering where food can be found.
So if you spot one of these unusual Riderwood residents, say welcome and thank you!