When Canada's big-city rats were enjoying the summer weather in 2001

Canadians were soaking up the sun, as were the rats.

"This is the kind of census increase nobody wants," the CBC's Alison Smith told viewers on The National, setting the trap for a shudder-inducing story on August 23, 2001.

"The number of rats in Canada's biggest cities is skyrocketing, spurred on by this summer's dry, warm weather."

Vancouver was one such city where a lot more rats were scurrying about.

'They have invaded'

"Thousands and thousands of them have invaded the waterfront and the back alleys," reporter Lynne Robson said, as a CBC camera showed some of those unwelcome city dwellers hanging out down by the water.

City officials were concerned about the risks the rising population of rodents posed for residents.

"They ... destroy food, property," said Domenic Losito of the Vancouver and Richmond Health Board.

"They can actually chew into house wiring and cause house fires, so they are a health and a safety concern."

A 'rat heaven' in Montreal?

The rat population was also on the rise in the big cities of Toronto and in Montreal.

In Montreal, Harold Leavey, a local exterminator, said that some of the old infrastructure in the city was hospitable to rats.

"The sewage system is old and crumbling, rats like that," Leavey, speaking in French, told CBC News.

Robson said the addition of deserted buildings and garbage on Montreal's city streets created a "rat heaven" of sorts.

Leavey said the warm weather, preceded by a mild winter, made for perfect weather for families of rats.

But Robson said one city official suggested a change in the weather would eventually make things less favourable for those rodents.

"It will rain and fill the sewers," said Robson.

"Sometimes when we have big rains, they can drown," the city official, Claire Bourassa, said spelling out the lethal nature of the hoped-for scenario a little more explicitly.