14202258_sThe average adult body weight of a rat averages 350 grams (12 oz) in males and about 250 grams (8.8 oz) in females. The adult rat can squeeze through holes or gaps the size of a quarter (0.955 inches (24.3 mm), jump a horizontal distance of up to 4 feet (1.2 m) (or vertically from a flat surface to 3 feet (0.91 m)), survive a fall from a height of almost 40 feet (12 m). This is on the average record, however, New York City rats can be big, and because of some yucky research, we now know just how big.

Matthew Combs, a doctoral student at Fordham University, and his colleagues collected hundreds of rats for an ongoing study to determine how the creatures colonize. But in the process, they’ve given us a better idea of how the rodents can range in size. In his research project, which aims to understand how rats colonize new areas so that the spreading of diseases can be better understood, Combs has observed that large rats often live close to food sources.

No, New York City rats aren’t as big as cats (at least the well-fed domestic ones), as Gotham mythology would have it. However, the vermin are of a heft that will give you nightmares in a New York minute. Combs recently showed off the biggest catch to The Huffington Post — a 675-gram (nearly 1 1/2 pounds) monster. It’s right here to disgust/terrify/fascinate you, or however you choose to express your shock.

There’s good news for musophobia sufferers. If you’re concerned that there’s some mutation out there, resulting in rodents of a gargantuan size, well … “I do not think there are any 3 pound rats in the city,” Combs told The Huffington Post last week. “There seems to be a physiological limit to their size at about 2 pounds. I would need some physical evidence to believe they can get any larger.”

The average adult rat in the study weighed about a half-pound, Combs told Atlas Obscura. For the research, dogs captured the bigger ones while the smaller ones fell victim to traps. Much-larger Gambian pouched rats have been found in the Big Apple, likely released as pets, Combs said, but he doubts there are breeding populations of them. He also offered some reassuring information about the larger of the regular NYC rats.

“Bigger rats do not necessarily mean more dangerous,” he said. The population of NYC’s common Rattus norvegicus, they number about 2 million, according to a 2014 study and New Yorkers can decrease their chances of encountering plus-sized varmints by avoiding dumpsters and other convenient rat buffets. “The older, larger rats can basically let the younger, smaller rats test out new food sources, which might help them avoid poisoning once they reach a certain maturity,” Combs said. “Larger rats also likely have a consistent and reliable food supply and don’t need to try new foods, which limits the chances that they get poisoned.”