TORONTO -- With many restaurants and other businesses closed due to COVID-19, rats are on the move in search of new food sources.

The closures, combined with physical distancing keeping many people at home, have resulted in less garbage being left on the streets and in dumpsters, removing the major source of food for rats and forcing them to scrounge elsewhere -- including your home.

"Maybe for months and months a rat colony someplace in Toronto is benefitting from restaurant trash and now suddenly it has disappeared," Bobby Corrigan, an urban rodentologist in New York, said in a telephone interview with "Like any mammal -- including humans -- when there's no food in your neighbourhood, you’re going to go looking for it."

Corrigan said he has seen changes in rat behaviours in his area amid the pandemic.

He said he has seen the normally nocturnal rodents out during daytime hours and getting close to humans. If worse comes to worst, Corrigan says rats will "very quickly" resort to cannibalism.

"Rats who are stressed out and in hunger pain don't act like they normally do," Corrigan said. "When strong, male rats of a colony get hungry, they will smell out where other rat nests are and they will go into those nests and, if there's young rats being nursed by a mother rat, the strong, male rat will go in and simply kill them," he said.

During the pandemic, Abell Pest Control says it has seen a 50 per cent increase in rat-related calls in Canada compared to this time in 2019.

"Rats can enter homes and buildings under door gaps, cracks in foundations or gaps around pipes. A determined rat can squeeze its way into an opening of only [one inch] -- that's about the size of a quarter," Abell's quality assurance auditor Dusana Bondy said in a news release.

The company reported that most calls are coming from urban centres, including Toronto, Halifax, Winnipeg, Montreal, Regina and Vancouver.

While rats may move to find new food sources, Kaylee Byers, a researcher at the University of British Columbia who specifically studies rat movement, says the rats won’t travel major distances.

"Rats don't usually move all that far, mostly they stay within the span of a city block, but previous research has shown that when there are few resources, rats will move further," Byers said.

She said the most a rat may travel is a couple of kilometres, but wandering, hungry rats can still wreak havoc.

"The most important reason to keep rats outdoors is their disease-carrying ability. Pathogens such as salmonella and E. coli can be transmitted via rats and these are very dangerous for humans to be exposed to," Bondy said.

According to the U.S. Centers for Disease Control (CDC), rats can spread approximately 35 different diseases to humans either directly through contact or indirectly via ticks, mites or fleas that have fed on an infected rat.

There have been no reports of rats carrying COVID-19, however the novel coronavirus has been found in other animals.

But Corrigan hasn't ruled out the possibility of COVID-19 eventually being seen in rodents.

"Even though the major transfer is by respiratory droplets, still you don’t want to touch anything that has a virus let alone coronavirus -- and if rats can carry other viruses, they can carry this one,”he said. "But it's not as though they are a major threat for transmission."

"We should think about how we keep our garbage the same way we keep our hands clean," he added.

When considering the long-term implications of rat movement during COVID-19, Corrigan said some areas will actually see fewer rats with business closures.

"Some rats will successful recolonize in these new areas… and other rats will die along the way. Some areas are actually going to benefit from this and see a decrease of rats in their neighbourhood," Corrigan said.

But Byers said the rats will likely return once those businesses reopen.

"Once those food resources become available again you can guarantee that those rat populations will rebound," she said.

Bondy said Canadians should take certain precautions to prevent a potential rodent infestation amid the pandemic.

"For restaurant owners and other businesses, especially during times of closure when rats can move around unnoticed, it's important to keep on top of your pest control," Bondy said. "The last thing anybody wants to be dealing with during this pandemic is a rat infestation to add to an already stressful time."

To prevent a possible infestation, Abell Pest Control recommends that Canadians:

  • Inspect the exterior of their home or business and seal up any cracks or holes
  • Clear their yards of clutter and debris where rats can hide
  • Keep a clean kitchen and store food tightly and securely
  • Make sure that no food is left out on counters
  • If there is food in a business, ensure it is sealed up