New York rats are big and bad . They sit calmly on the subway tracks, ignoring discomfited commuters on the platform. They stroll through Central Park as if they owned the place. They pretty much rule the East Village.

And they do not have much to fear from cats, a new study suggests.

In the report, published in Frontiers in Ecology and Evolution, the authors first present some background. Cat predation of rats has been studied before: Researchers in New Zealand, for example, analyzed scat from 229 cats and learned that almost all of them ate rats. The felines even seemed to prefer rats to birds.

But New Zealand rats weigh an average of 150 grams, or about five ounces, whereas rats in the most recent experiment in New York were more than twice as large. Bulk, it turns out, is an obstacle for cats who might otherwise dine on city rats.

It was not easy for the scientists to find a place to do their research. The lead author, Michael H. Parsons, a research biologist at Fordham University, said property owners generally want their rats killed, not caught and then released for study.