Mice may stare out at chances they dare not take, as the poet Ted Hughes observed—but rats are another matter entirely. When caught in a cat’s gaze, a rat might stare brazenly back. It may scurry around, apparently untroubled that a hungry predator is looking right at it.

This happened often when cats moved into a rat-infested recycling facility in Brooklyn, in the middle of Fordham University ecologist Michael Parsons’ experiment (for a study completely unrelated to cats). Parsons had wanted to determine how certain rat pheromones, like those of an alpha male, might influence the animals’ actions. “We wanted to understand [the rats’] behavior based on their own scents,” he says. “As a behavioral ecologist, I was like, ‘Let’s get rid of the cats so we can do our rat research’.”

The local felines, however, had other plans. They had found a suitable place to live and would not be driven out. Quickly deciding that trying to literally herd cats might not be the best use of their time, the researchers figured studying cats and rats together might offer some serendipitous benefits. “At some point we just said, ‘Wait a second, we don’t know what the rats will do around the cats’,” Parsons says. Plus, he had heard about organizations and programs like the Mayor’s Alliance for NYC’s Animals, Blue Collar Cats, in Washington, D.C., and Cats at Work, in Chicago—all of which involve turning feral cats loose in public facilities and businesses to fight rodent infestations. “That was one reason why I said, ‘Hey, let’s study what impact [the cats] have on the rats,” he says.

Parsons and his colleagues set up cameras around the Brooklyn recycling facility and fitted as many rats as they could catch with unique radio frequency tags (RFID units). This was “so that we can follow each individual and their behavior,” he explains. After that, and analyzing more than 300 videos of cats and rats on the floor of the recycling center, the results—published Thursday in Frontiers in Ecology and Evolution—were clear as day: “The cats didn’t really bother [doing anything] when the rats were on the open floor,” Parsons says. In one video, a rat walks calmly around the floor while a cat watches it from a box a few feet away.

Video footage from a study conducted in a Brooklyn recycling facility shows a cat apparently ignoring one of its supposed ancestral enemies.

Researchers did see some violent interactions, in which the cats actively chased the rats—but that was rare. In the hundreds of videos there were only three kills (“all ambushes,” according to Parsons) and 20 stalking events. The cats had no real effect on the rat population, Parsons says. “If you are paying [to feed] five cats to be around to control 150 rats, well, that’s not happening. Rats are still pouring out of the colony.”

One consolation prize might be that the rats did seem to behave a little more cautiously; they were about 20 percent more likely to move for shelter if they saw a cat. “They used to run from their east colony to the west colony, where the new rubbish collection comes in. After the cats, they would walk and sniff, walk and sniff,” he says. “Rats have terrible vision, so [if running toward the food] you could run right into an ambush. But walking, you have a better chance.”

Video footage from the Brooklyn study shows a cat attacking a rodent that has been conveniently cornered.

This bold behavior may seem surprising, considering cats’ popular history as the ancestral enemy of rodents. But not to Gregory Glass, a professor at the University of Florida who has studied feline and rodent interactions for decades. Glass, who did not work on the study with Parsons’ team, says rats are generally just too gnarly to make good prey for domestic cats. “Once that rat hits puberty, they are way too big and nasty for the cat to deal with,” he says. “You can watch a lot of cats and rats accommodating one another, easing by one another, eating out of the same trash bag.”

That means cats are not the greatest exterminators when it comes to rats, despite their reputation—and Glass says he scoffs at any initiative using cats to control rats. “What they do is a placebo. They make people who want to do something good feel better about themselves,” he says. “Sure, somebody might have a super-cat that will take lots of rats. But the super-cat will have to kill an awful lot of rats to make any sort of difference.” 

However, organizations like the Mayor’s Alliance for NYC’s Animals say programs putting feral cats to work are not entirely about pest control—and can sometimes be more about finding a home for neutered feral cats that cannot be adopted for various reasons. “Our main focus is trap, neuter, release. From time to time somebody may say, ‘Hey, I want cats to keep the rats and mice away.’ Then we try to make a match between those people and feral cats [already] being displaced,” says Kathleen O’Malley, director of education for the Mayor’s Alliance’s. “We make sure acclimation is properly done, and everyone lives happily ever after.” She adds that cats do sometimes prey on juvenile rats, and that a feral cat colony may be a deterrent to potential rat infestations.

Some businesses that have welcomed feral cats onto their premises—an old and time-honored tradition—are happy with their new employees. “Every brewery in the world once had a grain cat,” says Thor Cheston, co-founder of Right Proper Brewing Company in Washington, D.C., and the caretaker of his own grain cat named Oats. “We pay an exterminator a lot of money every month, but we thought having an extra layer of security would be nice.”