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Everything you need to know about rats in Chicago

Written by
Nick Kotecki

Living with rats is not a fact of living in Chicago, it’s a fact of life. We just see them more often than some cities.

Rats have generally followed humans as they spread across the world. They typically live everywhere people do, making them one of the most common and extensively spread mammals in the known universe.

As for Chicago, pest control company Orkin said the city has the most rats in the U.S., based on 2013 data (Orkin also says Chicago has the most bed bugs). The Chicago Transit Authority earlier this year launched a contraceptive program to get city rats to stop reproducing. It’s essentially food that acts as birth control for both males and females. But will it get rid of rats in Chicago? No chance. The rats are here to stay.

How many rat species live in Chicago?

Mostly just one. Chicago (and the world’s) primary species of rat is the brown rat, also known as the Norway rat, common rat, wharf rat and the less favorable street rat and sewer rat.

What do rats eat?

Chicago’s rats will eat mostly grains if they can, but really, these guys will eat practically anything on hand. They’ll eat your dog poop, garbage and food scraps, which, according to most studies, are plentiful. A 2014 USDA study said over 30 percent of food in the U.S. is wasted, making humans the perfect companion species for rats. Our furry friends might also gnaw on your discarded furniture to keep their teeth at bay (otherwise, a rat’s teeth will grow for its entire life).

How long do rats live?

About six months to a year. Females can begin producing offspring at around two to three months old and at a rate of up to seven litters per year. Females become fertile again two days after giving birth. Litters vary from about seven to 14 pups.

Where do rats live?

Rats like nooks and crannies, and this particular breed loves to burrow, often making extensive tunnel networks consisting of several tiers. Rats live in colonies and create a social pecking order like dogs and wolves. Odds are these burrows won’t cause any damage to your apartment or home.

How big do rats get?

Rats are anywhere from about 12 to 18 inches in length and can squeeze themselves into a hole about the width of a quarter. They can weigh 5 ounces to a little over a pound, on average.

Can rats swim?

Yes. Brown rats are very good swimmers. According to the city, rats can tread water for three days straight.

Do rats bite?

Sometimes. If you have the speed to catch and pick a rat up off the street, it will probably bite you just like any other wild animal, so please, no touching. But rats are likely as afraid of you as you are of them, so there’s generally no cause for alarm.

Do rats carry diseases?

Yep. Not always though. It’s a good idea to steer clear of wild rats just in case.

Are pet rats the same as rats on the street?

Yes and no. While they are members of the same species, pet rats have been selectively bred to be pets. Lab rats have also been selectively bred. Taking a rat from the street to be a pet is dangerous both to the rat and yourself. These are wild animals not intended to be kept in captivity and, again, they could carry diseases contractable by humans.

How can I get rid of rats?

Rather than using poison that could injure neighborhood pets, it’s best to make your living space undesirable to rats. That said, beyond picking up your trash and keeping your home clean, there is not much you can do. There is no effective repellent that works permanently on rats. Lethal control has proven to be a temporary solution at best. So we’re pretty much stuck with them. Forever.


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