Katie the dog and Sarah Darby entered Prospect Park in Brooklyn, New York, beneath a full hunter’s moon. Darby turned on Katie’s red LED collar, unclipped her leash and Katie sprinted off, looking over her shoulder to make sure her mistress was following.

Katie disappeared around a bend in the paved path that skirts the Long Meadow. When Darby caught up, Katie was circling a trash can. “Ready, Katie?” She tilted back the trash can. A plump rat darted out.

A blurred chase lasted only a second. Katie snatched the squeaking rat in her jaws, whipped her head back and forth, and snapped its neck. She dropped the limp rat, and Darby used a folded paper towel to pick it up by the tail and drop it in the trash can, among banana peels and muffin liners. It was Katie’s 363rd kill of the year.

Her 364th came nine minutes later. “Watch out,” Darby called quietly to a woman in a hooded sweatshirt who was jogging by the furry corpse, more than a foot long from nose to tail. “Oh, my god,” the runner said as she hurried off.

Katie weighs 5.5 kg and is about 4 years old. She is 28 per cent Chihuahua, 16 per cent pug, 16 per cent rat terrier and 40 per cent mutt. Darby, 50, an educational consultant by day, adopted Katie from a shelter in Texas, near the Mexican border, in 2022. Not too long after, Darby said, “I was walking her in a playground that had tons and tons of rats and she sort of revealed to me her interest in doing this.”

In 2023, Katie bagged 115 rats. With about a week to go this year, she’s closing in on 500. A colour-coded Google map, titled “Katie’s rats 2024”, shows that about 40 per cent of the kills were in Prospect Park; the rest were on the sidewalks of the Park Slope and Gowanus neighbourhoods. All were within about a kilometre of Darby’s home, and nearly all, she said, had occurred within the orbit of a garbage can or bag of trash. Katie’s most prolific month was September. For some reason, her most productive day of the week is Thursday.

Katie has found an endless supply of prey even amid mayor Eric Adams’s loudly declared war on rats, including his recent push to move the city’s signature mounds of trash bags from sidewalks into bins. The city’s rat czar, Kathleen Corradi, is introducing comprehensive pest management techniques in four “Rat Mitigation Zones”. In the Harlem zone, rats have been so mitigated that a social club of dog owners who took their dogs ratting in Manhattan every Friday night for 30 years recently gave up.

“You get one or two, but it’s not what we’re there for,” said Richard Reynolds, the organiser of the Ryders Alley Trencher-fed Society, better known as RATS. His ratters now split their hunting time between pursuing wild boar in the Deep South and for-hire work tackling mouse infestations at food warehouses.

But in Katie’s neighbourhood, rat sightings are up 11 per cent since last year.

Before she goes out hunting, Darby stands in her kitchen and folds paper towel sheets into perfect crisp rectangles.

“I used to bring only two, and then that was not enough,” she said recently as Katie sat beside her on the floor, eyes raised, ears focused, waiting for the sign that it was time. “Then I would bring four, and that was not enough. So now I bring six.” She slipped them into her purse.

The only night she ran out of paper towels was Octobr 10, a Thursday, when Katie killed eight rats, her record. Darby picked up the last two with a potato chip bag she found in the trash. Officially, Prospect Park does not have a rat problem.

“Rats are not an issue in Prospect Park, point blank,” said Morgan Monaco, president of the Prospect Park Alliance, the non-profit group that manages the 526-acre park. “Of course rats live here,” she added, “but they don’t pose the same kind of health hazards as in some other parks.”

On the streets, the city hopes a new rule requiring homeowners and small landlords to use rat-resistant garbage bins with lids will put a big dent in the rats’ food supply. Darby is sceptical. On another night this autumn, she and Katie were out street-hunting when Katie heard a scrabbling sound coming from a lidded trash can.

Darby rapped on the lid, as if knocking on someone’s door. A rat appeared at a hole, just below the lip of the can, jumped to the ground and dashed away. Another rat appeared at the hole seconds later and leaped. “That’s their highway,” Darby said. “They have their own entrance and exit, just like a cat door.”

A third rat jumped from the hole in the can, then a fourth, like rabbits from a hat. Katie caught one, Darby returned the dead rats to the can whence they came.

Over the course of the year, Darby said, she and Katie had developed new techniques. They demonstrated one on Second Street in Park Slope, at a cluster of three bulging bags in front of a handsome brownstone. Darby jiggled one of the bags, and Katie saw a ripple move beneath the skin. Katie chomped down and ripped a rat out through the plastic.

Though Darby feels a little hesitant messing with other people’s garbage — “We were sort of vaguely trespassing,” she explained as she left one trash pile — she said no one had objected. “The few times I crossed paths with an actual resident, they were delighted.”

Darby also feels bad for the rats sometimes. “But I love Katie more,” she said. “I grew up on a farm with a Border collie,” she added, “so I know what it looks like when a dog is doing the job that they were born to do — so alert and so alive in every molecule”.

New York Times News Service