Winnipeg plans ground squirrel control with deadly bait, asphyxiant foam

The City of Winnipeg is asking for the province's approval to control ground squirrel populations at 10 athletic fields using two pesticides that an animal welfare organization and a biologist warn cause a slow and painful death.

"Sometimes you may have to practice lethal control, even if you'd rather not," James Hare, a biological science professor at the University of Manitoba, told CBC News.

"But if you're going to do that — do it right. Do it in a humane fashion and in the most efficient way."

The decision to request approval for the pesticides comes after many fields were forced to close by the end of last season because of rodent damage, the city said. 

The ground squirrels dig holes that destroy green spaces and create a safety hazard for pedestrians, said Adam Campbell, a communications officer for the city, in a statement.

The city has applied for a permit to use Rozol RTU, a bait, and RoCon, an asphyxiant foam, at 10 fields this year. 

The treatment options pose limited risk to other animals and humans, Campbell said.

But Hare, who has been studying ground squirrels for 30 years, said the rodenticides proposed by the city are neither environmentally friendly nor effective. 

Rozol RTU is an anticoagulant that sometimes takes days to build enough concentration in a rodent's body to become lethal, Hare said. The bait keeps the squirrel's blood from clotting, causing it to die from hemorrhaging. 

The other rodenticide proposed by the city, RoCon, is supposed to kill ground squirrels by suffocating them in an "irritant" gas, Hare said.

For the product to work efficiently, there has to be a high concentration of it inside the burrows, Hare said. But their underground tunnels have various chambers and points of exit that can prevent the gas from accumulating. 

"Individuals will be exposed to lower concentrations. They will also suffer and, of course, potentially die a slower death than would be ideal," he said.

Ground squirrel holes can be anything from a nuisance to actively dangerous, said Liz Jackimec, general manager of Valour Community Centre. Its Clifton site is on the list of proposed fields. 

"Especially when you've got kids playing, and they're running around playing soccer, for example, you can sprain your ankle, break your ankle," Jackimec said. "Adults, too, can step in them and, you know, twist your ankle and that kind of stuff."