Cats may be deadlier than you think

Vicious killer isn’t necessarily the first thing to come to mind when you think of a cat. However, according to a new study, the cuddly creatures are responsible for a significantly higher body count than scientists had originally anticipated.

Surprisingly, their mammalian prey isn’t the stereotypical mouse. Instead, according to the study published in Nature, of its estimated median of 12.3 billion mammals killed yearly, creatures like shrews, chipmunks, and voles—a rounder, chubbier version of a field mouse— take the top spots. It’s also estimated that cats kill a median of 2.4 billion birds yearly.

The report, led by scientists from the Smithsonian Conservation Biology Institute and the Fish and Wildlife Service, included both domestic and feral cats. In producing the numbers, the scientists conducted a meta-analysis of 21 previously done studies. They extracted numbers from these studies, which were deemed to have a large enough sample size and consistent enough results to be meaningful, and standardized the findings to obtain the published figures.

Professor Greg Ball who studies birds and their photo-behavior, explained the impact of the report’s findings.

“The reality is that they [birds on the continent] haven’t evolved to have a lot of small feline predators attacking them and this is especially on younger birds,” Ball said. “We’ve known for many years that bird populations are very seriously negatively impacted by domestic cats being abandoned and becoming totally feral or just being allowed out. In some ways house cats being let out is among the worst situation because they’re given support.”

“When you have a house cat, you have someone taking care of it, feeding it, and at the same time subsidizing it to work in a habitat where it doesn’t belong. This new study tried to systematically document what the impact is on wild animal populations. And as thought, it’s bad.”

The study highlights the problem that scientists have known about. What is surprising about this problem is just how high the numbers are. It additionally gestures at the ongoing debate surrounding cats and their impact on wildlife. On one side of the coin are environmentalists who see cats as dangerous predators, and on the other are animal rights activists lambasting the number of cats euthanized every year. Both sides, however, recognize that there is a problem.

Ball noted that cats, as pets, come with a certain level of responsibility. “One of the responsibilities of owning a small tiger, which is what a cat is, is that it should not be exposed where it doesn’t belong,” he said. “And there’s very little awareness of this. Or it’s often ignored as not being significant. But it really is. We’re very worried about our migratory bird populations because of destruction in the tropics. It’s irresponsible of us to not work with our cat owners on how to manage their cats.”

Though it is unlikely that domestic cats will be prohibited from going outdoors in the near future, Ball offered advice to ameliorate the relationship between cats and wildlife. “At the very least I think people should bell their cat so when that cat is out it will make some noise,” he said. “I think the best thing is to keep your cat at home. Or, if it does go outside, keep it in a very well defined space so you can watch it.”

Ball also pointed out that allowing domestic pets outside poses dangers for itself as well as wildlife. “It’s dangerous for your cat,” Ball said. “The Kitty Cam (a University of Georgia project) has shown that cats are encountering all sorts of things that are harrowing. There were some pretty scary stories in there (in the article).”

The other side of the debate also acknowledges the dangers of allowing cats outdoors, however animal welfare activists point to feral cats as a larger contributor to the issue than their domestic counterparts. The study itself has shown that outdoor pets are responsible for only 29 percent of birds killed and —even less—only 11 percent of mammals killed.

In response to the problem of feral cats, various animal welfare organizations across the nation have adopted Trap-Neuter-Return (TNR) programs. Locally, the Maryland Feline Society runs a TNR program. As their website explains, the mission is to trap the feral felines, provide them with vaccines and ear-tag them for identification, before returning them to their “colony” where a caretaker provides them with food. The logic behind the program is that neutered colonies will not reproduce and the population of feral animals will decrease, thus tempering the threat to wildlife.