Zoologist Andrew Hebda says summer is peak breeding period for rats. ((CBC))

More rats than ever are scurrying around the Halifax Regional Municipality this summer, scientists and exterminators say.

Andrew Hebda, a zoologist at the Nova Scotia Museum of Natural History, said there has been a lot of demolition and construction in peninsular Halifax, which can disrupt the rodents.

"If you think about your average block, you've got about 75 rats per city block in here right now," he said Wednesday.

"The big problem is when they interact with us, and that tends to be more so when you start disrupting things, like, for example, road repairs, putting in sewage, blasting, or tearing down buildings."

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Hebda said rat populations in HRM run in cycles, and right now is a peak population time.

"You get these peaks and valleys, and this is one of those peaks. Midsummer, the rats are reproducing. They reproduce about six or seven times a year, lots of litters coming through," he said. "We've had some nice warm weather, plus lots of rain as well. So there's lots of food out there for them."

Resident Chris Foster said he's been seeing rats everywhere.

"There's just packs of them, sort of roaming around — lots around dumpsters and fields," he said. "I have a couple of friends who have them in their basements, and they haven't had them in their basements before."

Brian Betts, of Ace Pest Control, said he's getting more calls than ever about the large rodents.

He said that last week he received a call about an infestation in downtown Halifax, next door to a restaurant.

"We got down to the basement, and there's probably a five-foot pile of dirt that the rats have pushed out from under the floor of the building to create more harbourage sites," Betts said.

Both Betts and Hebda said the best way to keep rats away from your property is to clean up any debris where they can take shelter. They also advise to stop putting out feed for the birds, because it will attract rats.