Photo: Kirk Mastin/Aurora Photos

Cats—cuddly companions or fine-tuned killing machines? The answer seems to depend on whether or not you own one.

Ecologists from the University of Exeter and Queen Mary University of London asked cat owners in more than 50 U.K. households if they thought their cats were harmful to wildlife. The team wanted to learn if pointing out the actual toll cats take on the local fauna (birds, reptiles, and small mammals) influenced how their owners felt about and managed their pets. The results: It did not.

Owners’ opinions on their kitties’ capacity for killing generally stood unswayed even when faced with hard numbers: as many as 10 kills per month by some cats (and that’s just observed kills). This “ecological information,” as the paper, published in Ecology and Evolution earlier this week, soberly puts it, “is unlikely to alter their attitudes.” Owners tend to have foggy notion of their cat’s prey tally and often don’t see the hazy figure as a negative. “Several survey comments seem to suggest that owners see their pets as part of the natural ecosystem,” the authors write. “But it’s nature,” one survey participant pleaded.

Except these “love sponges”—Ernest Hemingway’s affectionate name for felines—aren’t exactly natural. They’re out in nature because of us. A 2013 study discovered that domestic cats—that includes both pets and feral cats—are likely the single greatest source of human-related U.S. bird and mammal deaths. The study, vastly exceeding previous estimates, suggests that cats kill 1.4 billion to 3.7 billion birds in the lower 48 states every year—more than buildings, vehicles, and poisoning combined .

At the end of the survey, the researchers asked participants what they thought of different cat management plans—namely, keeping them indoors or at least nearby. Most owners were not receptive: 52 percent said they would not try to keep their pet on their property at all times, and 46 percent said they strongly disagreed with the idea. “My cat chooses for herself whether to stay in or go out,” one participant wrote on the questionnaire.

Owners seem set on putting their cats first and nature second, the study authors concluded, despite the fact that keeping cats inside benefits both parties: Indoor cats are less likely to be hit by cars, get poisoned, contract diseases, get into fights, or fall victim to predators.

For those owners intent on letting their pets roam free, there’s the BirdsBeSafe cat collar, which, with its bright stripes and jingles, is supposed to make the cat a less effective predator. Avian ecologist and conservation biologist Susan Willson told Audubon the device was “100 percent effective” on her own “professional killer cat.” Alas, other owners, worried about burdening or endangering their pet with a collar, are reluctant to consider even this step, valuing their cat’s comfort above conservation—or maybe even conscience.