The City of Winnipeg has gotten approval to use pesticides animal advocates say are inhumane to control its ground squirrel population.

The province approved use of rodenticide Rozol RTU and asphyxiant foam RoCon at nine parks with athletic fields — some of which have been forced to close down over the past few years due to the effects of ground squirrels, a spokesperson with the city said Sunday.

The spokesperson said the city will begin applying the pesticide in early spring, as the squirrels wake up from hibernation. They said the animals dig holes that destroy athletic fields and greenspaces, and pose a safety hazard for the people who use them.

The approval, which was issued Thursday, comes amid concerns from animal rights advocates who say the products make the squirrels needlessly suffer and are not even an effective pest control.

The Winnipeg Humane Society said in a social media post Friday it was “extremely disappointed” by the decision and will be appealing it.

The society said the method the city plans to use to control the ground squirrel population will lead to “slow and painful deaths for the animals,” and could have unintended impacts on other species.

RoCon releases a gas that suffocates the animals. Rozol RTU is a blood thinner that causes the squirrels to die from hemorrhaging.

The city said the treatments are used in most major Prairie cities and pose a limited risk to humans and other animals.

Retired biology professor James Hare said he’s “shocked” the Environmental Approvals Branch approved the pest controls, particularly the anticoagulant bait, which he said takes days to kill the animals.

Usage ‘defeats the purpose’

“It ends up causing collateral damage to non-target species,” he said.

“Ironically in some sense … it essentially kills many of the predators that normally kill ground squirrels and keep ground squirrels in check. So you know, it kind of defeats the purpose.”

Hare said the predators can either eat the bait themselves, or ingest it indirectly by eating squirrel carcasses. Cats and dogs are also killed by ingesting it, he said.

“I certainly understand how you cannot have, you know, Richardson’s ground squirrels burrowing into athletic fields that people are running and children are playing on,” Hare said. “But by the same token, you should be using more humane methods.”

Last year, the province rejected a bid to use a different product — a sulfur gas called The Giant Destroyer — to kill the rodents, saying it heard from a lot of people who were concerned about the pesticide’s use and that it didn’t think the city had explored other methods.

The city said Winnipeg historically used poison to control squirrel numbers, but later moved to sulfur gas and carbon monoxide amid concerns the previous method caused undue suffering. It said while carbon monoxide was effective, the machines used to apply them were not always safe for staff.

The new permit set several conditions, including that the Rozol bait is applied before the birth of a new litter, and that the city puts up warnings.

The city said it will monitor the treated sites daily and remove any dead animals. Signage will be placed at sites where the products will be applied a day in advance, and will be kept there 24 hours after treatment.

The permit is set to run for a year.