For 10 years in a row, Chicago has been deemed “America’s rattiest city” by Orkin Pest Control. The city really wants to shake off the title — and a new effort in the Wicker Park and Bucktown neighborhoods could help.
A temporary pilot project, announced late last month, is bringing rat birth control to the alleyways behind several of the major commercial and residential areas in the two North Side neighborhoods. The program is sponsored by the Wicker Park Chamber of Commerce and the Special Service Area No. 33.
The aim of the project, which will last for three months with the option for an extension, is to reduce the neighborhoods’ rodent population by targeting the creature’s superpower: making lots of babies.
‘A humane control method’
The product, a solid pellet shaped like a sausage, being deployed is Evolve and was developed by Arizona-based company SenesTech.
Evolve’s active ingredient — cottonseed oil — impacts fertility in both male and female rats without causing them harm, said Bryan DiMenna, SenesTech’s vice president of sales. It’s been labeled a “low-risk pesticide” by the EPA, meaning it poses little to no risk to human health or the environment.
“This is a humane control method, not just for the rats but for all the other animals in the ecosystem,” DiMenna said. “It’s also not damaging anything, poisoning the water supply and has a minimal impact on the environment.”
That’s in contrast to rat poison, long a go-to choice for managing rodents. Poison can lead to a particularly brutal death for any animal ingesting it, said Maureen Murray, who leads the Chicago Rat Project at the Lincoln Park Zoo. The most common poisons stop the body’s blood from clotting, so the animal bleeds to death, either from an internal or external wound.
“Rat poison is a really big issue for biodiversity,” Murray said. “These rats have poison in their bodies, and they are running around being hunted by owls, hawks, foxes and other urban wildlife.”
At the same time, poison is becoming less effective as rats have not only learned to avoid it, but some have even developed a resistance to it. Murray conducted a study that tested 100 alive-and-well rats caught in Chicago alleys and found 75% had the poison in their system. And because they reproduce monthly and have short lifespans, Murray explained, it’s easier for rats to develop genetic resistance.
“I wouldn’t tell someone to coexist with rats and just put up with it, but they are animals and they are intelligent,” she said. “When we think about different types of abatement, it’s to go with something that doesn’t torture the animal and doesn’t affect the ecosystem as a whole.”
Enter birth control. Similar to the human pill, the rats have to continuously eat the birth control for it to be effective.
“There’s a cumulative effect with it,” DiMenna said. “We found a 61% decrease in birth rates in the first gestation cycle, so that’s a severe reduction in the litter. And within several cycles the rates drop down further and eventually stops their breeding.”
And because birth control is temporary, they’re not going to develop a resistance to it because it’s not killing them or permanently altering them, Murray said.
“Contraceptives are good because rats have evolved to reproduce really quickly. So slowing down the population makes more sense than trying to kill them all really quickly and is more effective in the long run,” Murray said.
‘Just do your part’
The birth control has been placed in alleys along North Avenue between Damen and Ashland Avenues; Ashland Avenue between North Avenue and Division Street; Milwaukee Avenue between Division Street and Damen Avenue; and Division Street between Ashland and Damen Avenues.
SenesTech will return in a couple weeks to put out the birth control along the residential alleys in that area, DiMenna said.
The city previously used a form of SenesTech-produced rat birth control called ContraPest, the Sun-Times reported in 2017. That came in a liquid form and was challenging to administer. The city has also tried using dry ice to kill rats.
The Chicago Department of Streets and Sanitation did not respond to requests for comment on the city’s efforts to manage rodents.
Managing the city’s rat population has clear benefits. Keeping the rat population low prevents the spread of certain diseases like leptospirosis, a serious bacterial infection spread through urine that can be fatal for humans and especially dogs.
Humans also have a responsibility to manage the rat population. Trash is the main attractant for rats, especially open and overflowing cans in residential and commercial alleys.
“Just do your part: Pick up after yourself,” DiMenna said. “If you see trash, pick it up. Keep your bins closed. Don’t wait till tomorrow.”