Kelly Beardall is scared of shadows. Every time she sees one, she expects it to scurry across her backyard.
The East Vancouver home Ms. Beardall rents in a comfortable residential neighbourhood with her roommates has been taken over by rats and mice. She sees them skittering across her backyard, sometimes up to four or five at a time. They dance across the telephone wire that goes from the garage to the house.
"I never used to be afraid of rats," Ms. Beardall said. But since the summer, the problem has become so bad she is reluctant to have friends over for dinner parties outside. "It's embarrassing," she said.
Although she has noticed rats outside in the yard since she moved in, this year she is seeing a lot more. And they have moved inside. She can hear them squealing in the walls.
Pest-control companies in the Lower Mainland and Vancouver Island say they are dealing with a surge in rats and mice. But researchers say more has to be done to keep track of rodent populations and the health risks they may pose.
"There's been an increase for sure," said Brett Johnson, president of the Structural Pest Management Association of B.C. He owns Assured Environmental Solutions, which serves the Lower Mainland.
He estimates he has received up to 30 per cent more rodent-related calls than this time last year.
This is typically a busy season for rodent removal. Mice and rats like to find shelter in homes as the weather gets cooler and natural cover such as leaves gets sparse.
But Mr. Johnson said warm winters of late have allowed more rodents to survive through to spring, and populations are growing.
Vancouverites assuming rodents are in only the grittier areas should think again.
"The west side, believe it or not, has always had more rats than other sections," Mr. Johnson said.
It is because homes there have "nice, lush yards and gardens" for refuge, he said, adding that food scrap bins also contribute to the problem.
Pest-control companies in Victoria are seeing the biggest increase, he said, most likely due to warm weather. But the spike is not consistent: Dalton Cross, a senior environmental health officer for Vancouver Coastal Health, said the number of calls he has received on behalf of the City of Richmond has been about the same over the past three years.
Chelsea Himsworth, lead researcher of the Vancouver Rat Project, which studies urban rats, said estimating the rodent population based on the number of calls to pest companies is too subjective and can be influenced by other factors.
Although questions around changes in the rat population are common, "if you have no baseline or ongoing surveillance, it's impossible to detect a change," she said.
The Vancouver Rat Project collected 725 rats in the Downtown Eastside from September, 2011, to August, 2012, and tested them for diseases that could be transmitted to humans.
Ms. Himsworth said it is impossible to get an exact number of rats in any one area. Rats live underground and come out at night, making it difficult to capture them. Instead, her group measured relative abundance from one area to the next.
She admitted her research is "not so glamorous as whales and grizzly bears," but she believes gathering data on rat populations is crucial. She said researchers know from studies and historical events such as the plague that rats can be a health risk to humans.
"We also know that they continue to be a source of disease for people living in other countries, and so we suspect there's likely some risk in Canada and in Vancouver," she said.