When Claude Thériault picked up the separate collection one day in March, he was surprised to find an unexpected visitor wandering around his door.
“When I opened the door, the opossum was right there on the bridge,” said Thériault, who lives in a suburb of Saint-Jean-sur-Richelieu, Que.
“I almost stepped on it!”
Didelphis virginiana, the marsupial commonly known as the North American or Virginia opossum – or simply opossum – lives primarily in the United States, Mexico, and Central America. Its northernmost habitat extends to the eastern municipalities of Quebec, southern Ontario and the Fraser Valley in British Columbia.
But in recent years, possums have often been spotted in the Montérégie region on Montreal’s southern coast.
Anecdotally, residents of communes such as Otterburn Park, Saint-Jean-sur-Richelieu, Varennes and the Saint-Hubert sector of Longueuil, as well as in the Kanien’kehá: ka (Mohawk) community of Kahnawake they all reported seeing them.
While the first sightings of opossums in Quebec date back to 1976, the population has been expanding since 2000, according to the province’s Department of Forests, Wildlife and Parks.
The animal is considered “established” in Montérégie, albeit at “low density”, and according to the ministry they have even been seen around Mont-Saint-Hilaire.
“People are often a little scared when they first see them because they look funny,” said Carole Lacasse, director of customer services at Proanima, an animal shelter with contracts with many South Shore municipalities.
He said the shelter often receives calls about wild animals in people’s backyards, including possums.
“They look like a big mouse. But they’re totally different from the mouse as an animal,” he said. “And they have mustaches … they’re actually ugly and cute at the same time.”
Lacasse says possums are not often seen near the banks of the St. Lawrence River. “But as you go south, we start to see them,” he said.
Expanding habitat range
Some opossums have also been spotted north of the Saint Lawrence River, up to Trois-Rivières in 2017, to Boisbriand in 2020 and to Barkmere, in the Laurentians, last year.
The ministry keeps track of reports of dead or injured animals but says that since it is not mandatory for citizens to report sightings of live opossums, the government has only a partial portrait of the evolution of the population.
Thériault said it’s only in the past couple of years that he has begun to notice animals in his neighborhood, sometimes, unfortunately, as victims of the street.
The possum on its porch had what looked like frostbite scars on its ears and tail.
“The two ears were quite dark and the same at the end of the tail and one of the ears has some blood,” he said.
Cold sores perhaps aren’t surprising, as possums don’t hibernate, said Jean-Philippe Lessard, an associate professor in the biology department at Concordia University.
Warmer temperatures, urban development attract possums to the north
Although Lessard’s research is not directly related to possums, his lab studies how biodiversity and species distribution are affected by human activities.
“Southern Quebec was probably too cold or the winters were probably too long for things like possums, wild turkeys and vulture turkeys until recently,” he said.
The opossum is just the latest in a long line of species whose habitats are shifting towards the poles as temperatures rise, according to Colin Garroway, an associate professor of biological sciences at the University of Manitoba.
“Southern species are moving north into the northern species ranges. This is joking with biology in all interesting ways,” he said.
For example, Garroway and his colleagues studied forays by more distant killer whales into Arctic waters and the crossing of once distinct species of northern and southern flying squirrels.
He points out that other species that we might think of as native to Quebec, such as the white-tailed deer and coyotes, also moved north in the early 1900s and 1940s, respectively.
These species, like opossums, are affected by urbanization, as they seek out man-made food sources, such as litter, or, in the case of deer, new buds that grow after trees are cut.
Both Garroway and Lessard say it’s unclear how the opossum can affect Quebec’s ecosystems.
“They’re weird, right? They come from a completely different evolutionary branch than our mammals here because they’re marsupials,” Lessard said.
“There may be things about their biology that make them different enough from our native mammal species that they don’t have much of a negative impact.”
However, possums are another sign of the effects of rapid global warming and urbanization, Garroway said.
“I think [opossums] they are just another indicator that we are changing things substantially, “he said.
A garden device, but not a tick repairer
Although possums are a relatively new arrival to Quebec’s backyards, Lacasse said the advice for dealing with them is generally the same as for other wildlife: leave them alone and don’t feed them.
“If you’re leaving food for a cat or something, don’t leave it overnight. Remove all food,” he said.
Possums are likely to seek shelter under a porch, but they don’t usually destroy property or act aggressively with humans, even going so far as to pretend to be dead – or possums – to avoid an attack.
But, like any wild animal, it could bite if it feels threatened and can’t escape, Lacasse said.
“If we ever meet one and they’re scared … let them be and they go,” he said.
While popular knowledge suggests that possums are a weapon against Lyme disease due to a voracious appetite for ticks, this is not the case. according to a publication by the Quebec Ministry of Wildlife.
Possums “scrub their fur meticulously” and eat any ticks they find, the ministry says.
But the idea that they help reduce tick populations is a “misinterpretation” of a 2009 study of captive possums that has not been replicated in the wild.
The ministry adds that “protecting a possum and keeping it close to home in the hope that it will protect you from Lyme disease is not only inefficient but also harmful to the animal.”