Climate change may give rats the chance to have more babies. Enter Rodent Birth Control

In Chicago’s Lincoln Park neighborhood, researchers are keeping a close eye on rats using cameras hidden in alleyways to see if the rodents will take the bait — because inside those tasty peanut butter pellets is a device that could keep the rat population under control.

Many scientists found that climate change – along with urbanization and density – is one of the reasons why some cities are seeing an increase in rat numbers. in peer-reviewed research. AAnd there’s a reason rats are considered vermin: they can spread disease to humans And their presence may also be negative impact on mental healthIssues that inspired research on controlling their population.

Birth control could be part of that solution, says Maureen Murray, assistant director of the Lincoln Park Zoo’s Urban Wildlife Institute, who is leading the study on Chicago’s streets.

“We’re evaluating whether contraception could be an effective way to control rats in cities,” says Murray.

Rat poisons, particularly anticoagulant rodenticides, have proven lethal to other species, A family of celebrity owls murdered in ChicagoWhile in New York City, Toxic levels found in flock of owls. Now, some researchers and municipal governments are hoping to find methods of pest control that are less harmful to the environment.

Climate makes rats a ‘ticking time bomb’

In more northern North American cities across the US and Canada, winter poses a major threat to the survival of rats, which “they cope with by ceasing reproduction almost completely during the winter,” said Bobby Corrigan, a rodentologist based in New York. But the effects of climate change on weather patterns are giving rats a chance to “put out just one more litter or half a litter” before they shut down for the colder months.

And just that small increase is enough to create a “ticking time bomb” for the disease to easily spread from rats to humans.

“They’re active in sewers and they’re active in slaughterhouses and areas where there are lots of areas for bacteria and viruses to get a foothold,” says Corrigan, who has been studying rats for decades, getting his start by hanging bait traps in New York City sewers as a teenager.

In Chicago, there is a public health warning about leptospirosis – a disease caused by Leptospira bacteria that can live in flood water and spread to humans when they come in contact with rat urine. (Rats around the world can carry the bacteria.) Historically, it has been more common for people in flood-prone, tropical parts of the world to contract leptospirosis, but that’s changing, says Murray, manager of the . chicago rat project But who is located in PEI

Instead, places like Chicago “are seeing a rise in cases and someone died from leptospirosis last fall,” she said. “It seems to be increasing, probably partly because of climate change.”

In Canada, leptospirosis is not a reportable disease, so there are no public records of cases.

Rat Birth Control Testing, One Street at a Time

Testing rat birth control is no easy task. Murray’s team is using a non-hormonal product, Wisdom Good Bites, which contains Thunder God Vine root extract. The root, which is used in Chinese medicine and sold as a natural health product, contains compounds that Murray says reduce the fertility of rats by affecting sperm production in men and egg release in women.

Because it does not sterilize rats, most of the population must continually eat the bait – and its hidden birth control – to keep the numbers down.

Murray and his colleagues run studies on the streets of Chicago, distributing peanut butter pellets laced with birth control. Since rats are difficult to count, the team relies on cameras to monitor the amount of bait and “rat activity” in the streets.

The team’s control lanes have the same setup, only with placebo peanut butter pellets, meaning they do not contain contraceptives.

“Any difference we see in rat activity over the course of the study, we can attribute to the contraceptive — not to anything else happening in the environment,” says Murray.

Wisdom Good Works, the nonprofit that developed Good Bites, sold the pellets to the Lincoln Park Zoo at cost and did not provide any funding for the study.

The pellets that Murray and his colleagues are testing are not commercially available in the US, but are Other non-hormonal products Which are in the market. There are no rat contraceptive products registered by Health Canada under Pest Control Products ActWhich means they cannot be legally used by individuals, municipalities or researchers in this country.

But cities across North America are working on this idea; City Council of Ottawa thought about it and toronto Rat Response Plan Contraceptives are mentioned, but none have applied to Health Canada for an exemption.

A pilot project is underway in New York City Two non-hormonal contraceptive productsWhile Boston gave up using birth control for rats After a pilot project in Jamaica Plain neighbourhood. baltimore And WashingtonDC has also begun testing or using contraception to slow the growth of the rat population.

Does science support rat contraception?

But some scientists doubt that these products work, at least not in big cities.

“We need more evidence that these things work,” says Professor Steven Bellman of the University of Greenwich in London.

While Bellman says there is “good evidence” that some non-hormonal rodent control products can be effective in a laboratory setting, he does not think there is “very good evidence that it works in the field.”

“I’m afraid right now people are making money from it and they don’t want to question it very carefully because it’s their business,” he says.

In an email, Loretta Meyer, co-founder of Wisdom Good Works, says the nonprofit “has a mission of improving our environment by reducing the use of rodenticides as a result of rigorous scientific testing,” unlike commercial suppliers of other products sold in the US.

The special compounds of Thunder God Vine in Good Bites have been shown in peer-reviewed research to be as effective as a contraception in some rodents.

Bellman’s own research has focused on using hormonal contraception for various rodent species, including studies in Tanzania and Zambia, where he says pest infestations lead to crop loss and food insecurity.

Corrigan said that even though rat contraception works in theory by reducing the number of rat litters, there are other factors involved.

For example, this type of device may work best in a contained setting, such as a farm dealing with a rodent infestation. In a city like New York, where there are disparate populations of rats in parks, streets, sewers and subways, rodentologists say it could become a game of whack-a-mole.

“How can we get contraception to diverse fragmented populations?”

He says a more sustainable solution in cities includes securing trash, which New York City has started Pilot project to keep garbage in containers Instead of being placed on the curb in plastic bags.

After all, rats flush out feces or urine-filled debris from their burrows every few weeks “to keep their house clean,” says Corrigan.