Chicago rat birth control pilot program expansion shows promise in Lincoln Park

Chicago's rodent problem is well known, but a new pilot program testing rat birth control to curb the population in problem areas is underway to help rein it in.

Rat birth control are light brown pellets that officials say are safe for any animal to eat, and are only effective in rats.

The concept behind the program is simple: boxes are loaded with the rat birth control pellets, the rats in Chicago munch on them, and fewer rats are born to these streets.

The pilot program was spearheaded by 43rd Ward Alderman Tommy Knudsen, and is running for the next six months.

"It's not harmful! Humans can eat this and it will have no impact. I'm not recommending that of course!" he said. "It also is potentially a more effective way to reduce the rodent population."

Knudsen said the rat birth control was effective in Boston, and after two endangered owls died eating rat poison in his ward, he teamed p with the Lincoln Park Zoo and Chicago Bird Alliance to get the animal-friendly program off the ground.

"It was very grassroots. It was so clear from the get-go that we would not be able to use city funding," he said.

So the program is being funded entirely through donations, with $40,000 raised privately. They've partnered with the Department of Streets and Sanitation to target some of Lincoln Park's rattier streets.

The pilot program compares streets using rat birth control to streets that aren't.

"The locations of where the experiment is currently happening are anonymous," Knudsen explained. "We want to make sure the rat enthused Chicagoans don't go out to our pilot alleys."  

Rats can have up to 10 litters a year,  and can reproduce again immediately after delivering. The city's Bureau of Rodent Control has around 20 baiting crews throughout Chicago during peak season, responding to more than 100,000 service requests per year.

The larger goal is to make this program a model for the city.

"First we have to show that it worked here and then scale it slowly. We can't do this all at once," Knudsen said.

The Chicago City Council just made moves to support the program for the next six months.

ABOUT DSS RODENT CONTROL 

• The Department of Streets and Sanitation (DSS) is dedicated to keeping Chicago clean and healthy, and we continue to proactively address rodent abatement as a free service to residents.
• The Norway rat is the species found in Chicago.
• The Bureau of Rodent Control has between 20-25 baiting crews on the streets citywide during peak season, and we respond to more than 100,000 311 service requests each year.  Crews bait all alleys and parkways, and residents' backyards with permission. 
• The Bureau of Rodent Control responds to 311 requests and proactively addresses rodent baiting through door-to-door abatement, face-to-face engagement with residents, and informational materials.
• The Bureau strives to complete all 311 requests within five days. Response times can get longer during peak summer months when rodent activity increases.
• We have increased outreach and education in communities by participating in more community-based events, such as town halls, resource fairs, and Aldermanic meetings, which has led to an increase in block baiting projects
• We repair or replace damaged garbage carts to cut off potential food sources keep rodent activity at bay.

ABOUT THE CONTRACEPTIVE STUDY

• The City is conducting a pilot study to determine the effectiveness of contraceptives as an alternative to rodenticide. The study is in partnership with Lincoln Park Zoo, the Chicago Bird Alliance, and the 43rd ward office.
• The study began in August 2025.
• The study is ongoing, and we expect to have initial data in summer 2026. The data will inform future activities and help develop a strategy to expand the program if it proves effective.