They have fur like beavers, teeth like beavers and burrow in the same places as beavers — but they’re much more dangerous.Â
It’s been decades since once was last spotted in Ontario, but still the province isn’t taking any chances with the nutria, a mammal often confused with beavers and muskrats. It’s one of the latest additions to the province’s invasive species list.
The list is often reserved for invasive insects, plants and fish — nutria is now one of two mammals on the list, joining the notorious wild pig. It was added alongside a handful of other species on Jan. 1, including certain types of crayfish, a fish called ide and an aquatic plant called oxygen weed, among others.
The only province where nutria have been spotted is B.C., according to Matt Smith of Ontario’s Ministry of Natural Resources and Forestry.
While that population is unlikely to “march all the way across the country, certainly in any quick timeline,” Ontario will most likely have to deal with nutria coming from the southeastern U.S., Colin Cassin, policy manager at the Invasive Species Centre, told the Star. And they’re threatening enough for the province to start raising its defences now.
What are nutria?
Many people can confuse nutria with beavers, muskrats or even capybaras, but they are often smaller with a ratty tail. They have bright orange teeth (though so do some beavers) and hail from southern South America, near Paraguay and Uruguay, but were introduced to North America in the late 19th century for fur farming, according to Smith. The last time nutria were spotted in the province was in the 1950s — four were apprehended near Hymers, a village west of Thunder Bay.
“The origin of these individuals remains unknown,” said Smith, “however, it is speculated that they could have escaped either from a local fur farm or spread from feral populations in Minnesota.”
Most populations of nutria in the United States are descendants of “escapees” from those fur farms once the market for fur collapsed, Smith said.
Why are nutria harmful?
Like most other invasive species, nutria “reproduce at really high abundance, very quickly and outcompete native species,” Cassin said, but the beaver-imposters specifically pose a major threat to wetland habitats in southern Ontario.
The province’s wetlands are already under pressure and “really, really threatened,” Cassin explained, they’re often home to species already at risk and southern Ontario is one of the biggest areas of wetland degradation generally.
Just over a year ago, in December 2022, the provincial government overhauled its wetland protection system, changing the way wetlands are evaluated — critics warned the new system would leave the lands open to development. At the time, the province’s auditor general Bonnie Lysyk warned in an annual report, “Many wetlands in or near urban areas in southern Ontario have never been evaluated, meaning that wetlands important for urban flood control are still vulnerable to being damaged or destroyed.”
Nutria, unlike other species that also reside in wetlands like beavers or muskrats, “pop holes into wetlands or in shorelines” in an attempt to eat tubers and roots, causing degradation to “the vegetation that holds the soil down and gives the water’s edge its structure,” Cassin said. That can be particularly dangerous for structures like bridges and dams built that require stability in the bank.
The semi-aquatic rodent can also cause economic damage, by damaging crops or by weakening irrigation structures and levees.
In addition, they may bring harmful pathogens, like tuberculosis and septicemia, and parasites, like blood flukes and tapeworms to humans and other animals, according to the Invasive Species Centre. One particularly harmful parasite, a nematode often found in nutria, can cause a “nutria itch,” according to the Centre, and can be found in drinking and swimming water contaminated by nutria’s waste.
What is the invasive species list?
There are two levels to the invasive species list, Smith explained: “prohibited” species and “restricted” species. Nutria falls into the former, meaning sweeping limits can be placed on the buying, selling, transportation and releasing of the invasive species and empowers conservation officers to enter property to confirm its presence. “The intention is to prevent them from becoming established if they are found,” Smith said.
Restricted species, like the wild pig, are just regulated, without wholesale prohibitions, especially because they are used on farms, and “we didn’t want to shut down the entire hog industry,” Smith added.
But, “not all invasive species are created equal,” Cassin said — wild pigs are possibly “pound for pound” one of the most problematic, and “they’re very heavy.”
And the invasive species list is usually reserved for “the next big species” that might pose a threat to the province’s ecosystems to prevent “the emerald ash borer’s of tomorrow as opposed to the emerald ash borer of 20 years ago,” Cassin explained. The emerald ash borer is a notoriously invasive wood-boring beetle across eastern Canada.
How to spot nutria and what to do when you find one
“If people see nutria in the wild, they shouldn’t attempt to capture or kill (them),” Smith warned, “but they can and should report that sighting.”
Anyone who spots a suspected nutria can call the toll-free invasive species hotline at 1-800-563-7711, Smith said.
There’s also an app for reporting nutria, or other invasive species, that Cassin recommends — EDDMapS, a “citizen science application” where people can submit suspected invaders and a wildlife expert on the back end will confirm the sighting.
“It can be difficult, I think, for people to definitely identify correctly some species,” Cassin said. “But any reporting is good reporting.”
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