Ottawa explores rat birth control to curb population

Efforts are underway to combat growing rat populations in two of Ontario’s largest cities, as the rodents that typically lurk underground become more visible thanks to a combination of construction and climate change.

In Ottawa, the city is exploring a form of rat birth control that is not yet legal in Canada.

Council recently supported a motion brought by Coun. Laine Johnson that asks Health Canada to expedite the review of a product called ContraPest, which is already being deployed in Seattle.

ContraPest works by inducing early menopause in female rats while reducing sperm production in males.

Johnson called it a better solution than rat poison because rats have the ability to “learn” which food sources are bad for them and adjust their behaviour.

A trial of the oral contraceptive was conducted in Washington D.C. in 2019, but the Department of Health said “the results proved inconclusive” and stopped using the product.

“For the province of Ontario, that rat is out of the gate,” said Johnson, the Ottawa councillor. “So we unfortunately have to work reactively instead of proactively as Alberta was able to back 70 years ago.”

Karen Wickerson, the province’s rat and pest specialist, doubts whether the humane birth control strategy suggested by Ottawa would be enough to fight the problem plaguing North American cities by itself.

“They have to continuously eat (the birth control) for (population reduction) to continue, so I think there’s a lot kind of missing from that strategy,” she said.

Wickerson has been at the helm of the province’s rat control program for four years, and says that a multi-pronged approach is necessary, but ultimately the province prescribes to a strategy of elimination based on vigilant citizen reportage.

In Toronto, the municipality’s infrastructure committee recently adopted a motion asking city council to direct staff to craft an “action plan” to reduce rats in the city.

The motion, put forward by Coun. Alejandra Bravo and Deputy Mayor Amber Morley, is a response to residents’ concerns about a rise in visible rats in local neighbourhoods, Bravo said.

“It’s a really critical quality-of-life problem when people have all of a sudden been confronted with rats coming into their home or into their business or their place of work … a bunch of factors (have) come together to create this kind of perfect rat storm.”

A sharp increase in construction in the city, due to transit projects and housing development, has disrupted rat habitats deep underground, driving them into open spaces where people can see them, Bravo said.