Winnipeg is going ahead with a plan to use a deadly bait and an asphyxiant foam to control its ground squirrel population.

The management program using Rozol RTU and RoCon began Tuesday, the city said in a news release.

Athletic fields at nine parks in the city will be treated with the rodenticides, which were approved for use by the province in March. Animal advocates say the products make the squirrels needlessly suffer and are not an effective pest control.

Rozol RTU is a blood thinner that causes ground squirrels to bleed out and die, while RoCon is a foam that expands and suffocates them.

The Winnipeg Humane Society and Animal Justice, a national animal law organization, are part of a group appealing the provincial permit.

Animal Justice said in a new release it is asking the province’s environment and climate change minister, Mike Moyes, to suspend the permit immediately. The organization cited flaws in the public notice process, among other things.

The City of Winnipeg said it will form an environmental advisory committee to explore future pest management options, with the licence only in place for the 2026 season.

The city said ground squirrel holes pose a safety hazard, and some fields have been closed over the last few years because of the damage the animals cause.

The sites will be monitored daily to help mitigate harm to other animals, the city said. Dead ground squirrels will be promptly removed, with signage posted 24 hours before and after treatment, the release said.