Wildcats seem to be pathetic at controlling New York rats

People often assume that cats kill rats in the city with enthusiasm, but this is perhaps only an urban legend.

Michael Parsons, a behavioral ecologist, said the ferocious cats captured in the video were eager to see rats hiding around a waste collection center in Brooklyn. But cats have rarely killed or even hunted rats. Cats are not a good choice to control the rat population, Parsons, a visiting scholar at Fordham University in New York, and his colleagues suggest Sept. 27 Borders of the environment and ecology.

Cats usually prefer smaller prey, he says. A 20 gram bird or a 30 gram mouse can not defend itself with the acute ferocity and weight of a Norway rat. The adult rats at the Brooklyn Waste Treatment Center have a weight more than 10 times higher, an average of about 337 grams. For 79 days, cameras in the center showed that cats killed or nearly killed only three rats. This poor performance would do little harm to a rat population.

Parsons and his colleagues had initiated another study in rats when they noticed that five wild cats were moving around the rats that the researchers had been able to do at the waste treatment center. The researchers first bristled at the intrusion and then realized that it was an excellent opportunity to study wild animals in real-life situations, Parsons said. Trying to use laboratory rats to understand the life of rodents in freedom is like extrapolating "knowledge of the wolf, for example from a Chihuahua".

The cats in the waste site paid attention to the rats, sometimes even sticking a feline nose into the hole in the wall that the rats used as a home entrance. The rats also seemed more cautious, and the more cats roamed the site on a given day, the less likely the rats would be spotted, the tests showed. These apparent disappearances could be the reason why people believe that cats help suppress rat populations. But in truth, rats are probably still there. They are just harder to see.

Cat attacks on rats were rare. Of the 306 active animal video clips collected, only 20 showed a cat tracking a rat. The rare murders took place when cats had the advantage of fighting a rat trying to hide behind its walls. One clip showed a partial hunt and "very hesitant," says Parsons, "like a stop-and-go dance that they do. When the rat stops, the cat stops too.

More hungry cats are more engaged in rat hunting, and some people who release cats to control a rat problem are holding back food to encourage hunting, says Parsons. But he argues that starving an animal to force it to face less favored and dangerous prey is "a horrible thing to do."

The results of the study conducted at the Brooklyn Waste Treatment Center go against the popular opinion. But these results are consistent with previous findings from Baltimore Alleys, where cats were similarly around larger rodents. "Cats sometimes catch rats, but not very often and not to the extent that they reduce the size of rat populations," says Gregory Glass, a disease ecologist who studied Baltimore rats.

Wild cats have other disadvantages, in addition to the reluctance of rats. Wildlife is difficult for cats and increases the risk to wild birds, says Susan Willson, tropical bird ecologist at St. Lawrence University in Canton, New York. estimates for the cat kills one billion birds a year (SN: 23/02/13, p. 14).