A young female opossum growls at Pam Richardson, assistant gamekeeper at Maine Wildlife Park in Gray, on Oct. 22, 2012.

When the motion sensor light on the porch switched on at 11 p.m., Susan Dolloff figured it was the stray cat that roams her neighborhood in western Maine. Her family puts food out for the feral feline. They love animals, both wild and domestic. But that night, it wasn’t the cat.

Its long snout was buried in a bowl of meat scraps. An opossum was their unexpected visitor.

“Then it kind of nosed around where we had been storing some birdseed,” Dolloff said. “Then he was in the recycle bin.”

Opossums have a varied diet.

The wild critter is fairly new to the state, having expanded its territory north into southern Maine over the past decade. More and more, Mainers are encountering this highly adaptable marsupial.

“Now, it’s like there’s a possum under every bird feeder,” Keel Kemper, state regional wildlife biologist in central Maine, said.

“I’d be surprised if they have opossums in Jackman yet,” Kemper said. “But even where I am in central Maine, they’re really getting common, particularly this fall for some reason. People are just encountering them, and now we’re receiving complaints of [them being a] nuisance.”

‘They aren’t pretty’

With a long, tapering snout and a nearly-bald tail, opossums are often mistaken for giant rats, measuring 2 to 3 feet long. However, the two animals are not even remotely related. Opossums are a primitive mammal, their origins reaching back to 65 to 90 million years ago, and they’re the only marsupial in United States. They carry their babies in external pouches, like a kangaroo.

They also boast 50 teeth — more than any other mammal.

“They aren’t pretty,” Dolloff said. “The first night we probably watched him for 20 minutes or half an hour, just watching through the window.”

Despite the creature’s less than charming appearance, the Dolloffs have decided that they wanted it to stick around. Living in the mountainous forest of western Maine, the couple enjoys watching wildlife, and they usually don’t play favorites. They feed the birds, and they feed the squirrels. They welcome deer to their yard, as well as moose.

“I don’t mind the opossum being around,” Dolloff said. “I’ve read that they’re very good at getting ticks out of your yard, and I’m in favor of that. So as long as it leaves my cat alone, I’m OK.”

Opossums will bare their teeth, growl and hiss when threatened, according to the Maine Department of Inland Fisheries and Wildlife, but they are generally not aggressive animals and seldom cause problems for homeowners. Nevertheless, Kemper has received several calls recently from people who are concerned they might be attacked by these relative newcomers.

“I’ve been somewhat surprised at the alarm some people have when in fact this [animal] represents very little threat to us,” Kemper said. “This thing moves in slow motion. Even a fast-running possum isn’t fast. These people are afraid they are going to attack or lunge at them, but the opossum defense mechanism is to ‘play possum.’”

“Playing possum” is a catatonic state that the opossum uses to trick predators. During this state, the opossum’s mouth lolls open and it secretes a foul-smelling substance to simulate the smell of death. This will often cause the predator to walk away, tricked into thinking the opossum is rotten.

Another way opossum protect themselves is by climbing. They use their prehensile tails to grasp at things, like tree branches, and they have digits on their hind feet that act like opposable thumbs.

They’re also immune to snake venom.

Struggling through winter

Opossums are adaptable because they’ll eat practically anything and they will create dens nearly anywhere that’s dry, sheltered and safe. This includes woodpiles, hollow stumps, rock crevices and under buildings. But like any creature, the opossum does have vulnerabilities. One is that the creature is not particularly well suited for the Maine winter, for a number of reasons.

A nocturnal animal, the opossum doesn’t hibernate, nor is it in the habit of storing food for the winter. Instead, it forages year-round. Therefore, when food sources are scarce during the winter, they can easily starve.

In addition, the opossum isn’t built for the cold. State biologists and wildlife rehabilitators in Maine have frequently found opossums with frostbite on their naked ears, tails and toes. And because the animal doesn’t put on much fat for the winter, it can have a difficult time maintaining its body temperature.

“They struggle with our Maine winters,” Howie Powell, assistant superintendent for the Maine Wildlife Park, said. “In fact, it’s not uncommon for them to seek shelter in people’s outbuildings, in sheds and people’s garages, to hunker down. We’ve found them on our property, in fact. Cleaning out storage areas, we find them rolled up in a ball under equipment.”

Regardless of their vulnerability to the cold and barren landscape of winter in Maine, some opossums seem to be surviving, Kemper said. And he believes it’s because they’re finding shelter — often manmade shelter.

“I don’t think they’re out in the middle of the Great North Woods,” Kemper said, “but they’re able to find their way under people’s houses, and there are urban habitats where they’re able to eat red hot dogs and live off the warmth of dryer vents.”

Pest or guest?

The opossum returned to the Dolloffs’ porch just the other night, and they’ve spotted it under their bird feeders — a sign that the animal has found a suitable spot nearby to weather the winter.

“We think it’s staying in the barn,” Dolloff said.

While the Dolloffs don’t mind having a resident opossum, some people do. After all, due to their need to forage for food, opossums will get into vegetable gardens, trash cans, recycling bins, compost piles, stored grain and chicken coops. The best way to rid yourself of an opossum is to block these food sources, according to the DIF&W. Store your garbage, compost and other sources of food in secure containers; fence in gardens; install predator guards on fruit trees; clean up barbeque areas and fallen birdseed; and if you must feed pets outdoors, do so in late morning or at midday, then pick up food well before dark.

Another way to discourage opossum from settling near or in your home is by eliminating access to potential den sites, such as chimneys, attics and spaces under houses, porches and sheds. To do this, inspect the buildings on your property and close any potential entries with mesh hardware cloth, boards or metal flashing. Or, another way to make a den site unattractive is by adding lighting to it or a portable radio. Just be sure not to close up a den site with an animal inside.

Whatever you decide — pest or guest — it looks like the opossum is here to stay.

“They’re a part of our urban wildlife now,” Kemper said. “They’re expanding north, and they’re expanding west, just like a number of other things. Cardinals, turkey vultures — there are lots of examples of range expansion [in Maine].”

The good news is that opossums don’t have a track record of being aggressive to cats and dogs. They’re a clean animal, spending much of its time grooming, like a cat. And while all mammals are capable of carrying rabies, opossums rarely carry the disease. In the U.S., the animals most likely to carry and transmit rabies are raccoons, skunks, bats, foxes and coyotes, according to the U.S. Centers for Disease Control and Prevention.

“Don’t panic,” Kemper said. “It’s all good. Just give them their space.”

Aislinn Sarnacki

Aislinn Sarnacki is a Maine outdoors writer and the author of three Maine hiking guidebooks including “Family Friendly Hikes in Maine.” Find her on Twitter and Facebook @1minhikegirl. You can also...