WASHINGTON, D.C. — They creep through dark alleyways, peer behind trash cans and look inside old takeout containers.

They’re not rats, they’re Rat Rangers.

These rangers work to educate D.C. residents about ways to prevent rat infestations without using poison. They organized after a 2024 City Wildlife study showed large numbers of D.C. wildlife with blood-clotting issues tested positive for rodenticides.

On a weeknight in late September, head Rat Rangers Holly Gerberich and Gerard Brown, wearing matching t-shirts with a rat on the front, lead two dozen D.C. residents down a dimly lit alley. The group is equipped with head lamps, closed toe-shoes and not nearly enough mosquito spray.

Gerberich, an anthrozoologist, tells the crowd that a healthy pair of healthy brown rats living in a city can produce 15,000 descendants in a single year. Despite the use of poison, traps and even birth control, rat numbers in Washington, D.C. are on the rise.

A group gathers for a rat walk in front of the Bruce-Monroe Elementary School in the Park View neighborhood of Washington D.C..

Claire Harbage/NPR

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Claire Harbage/NPR

But rats aren’t really the problem, she says, humans are.

“The reason that they’re here is because we provide an ideal environment for them,” Gerberich says. “How do we make our environment less welcoming to rats?”

The answer, she says, is to get humans to understand why they can’t leave garbage and waste out for rodents to feast on. And the best way to do that is to show people the problem up close.

Holly Gerberich, anthrozoologist and urban rodent specialist who leads rat walks with DC Rat Rangers in Washington D.C..

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Claire Harbage/NPR

The group doesn’t have to look very hard for signs of rodents. The alleyway they’ve ventured down is crowded with overflowing garbage cans. They stop next to a squished bag of dog waste, dinner leftovers and the remnants of a stick of butter.

“Sanitation is rodent control, truly,” Gerberich explains. “What we’re seeing out there is that individuals have a much bigger role in rat population prevention than they realize.”

Making the point for her, two long rat tails stick out from the top of a trash can. Sensing trouble, one plump rodent makes a run for it: It leaps on top of a sideways bin, then flings itself from can to can, dropping behind a fence and scurrying off in the dark.