Cat owners who let their furry friends roam outside are familiar with the "gifts" they bring home. This behavior results in billions of birds and small mammals falling prey to a cat's claws, reports Jonathan Lambert for Science News. In an attempt to curb cats' impact on wildlife and investigate why felines still have the urge to hunt despite being well-fed, researchers at the University of Exeter in England designed an experiment to explore if a cats' extracurricular desire to hunt came from something lacking in their diet or from natural instincts, Science News reports.
When cats were fed a diet with a higher meat content or increased regular playtime, it reduced their hunting instincts and, in return, lowered the amount of wildlife casualties, reports Ed Cara for Gizmodo. The study was published this week in the journal Current Biology.
A total of 355 domestic cats from 219 homes known to bring back kill in England were recruited for the experiment. All cats were observed in their natural settings for seven weeks before any modifications to daily activity or their diet occurred, reports Gizmodo. These initial observations provided baseline data for how frequently each kitty brought home prey. Then, the researchers introduced one group of cats to a grain-free, high-meat diet. Meanwhile, another group got an extra five to ten minutes of play each day or a puzzle feeder enrichment toy meant to stimulate the feline's mind, Science News reports. The researchers also tested brightly-colored collars and bells to see if these devices deterred feline prey, reports Jack Guy for CNN.
Cats with the grain-free, protein-rich diet brought home 36 percent fewer dead animals than cats with unchanged diets, reports Layal Liverpool for the New Scientist.
"Some cat foods contain protein from plant sources such as soy, and it is possible that despite forming a 'complete diet,' these foods leave some cats deficient in one or more micronutrients—prompting them to hunt," says Martina Cecchetti, a graduate student at Exeter involved with the study in a press release.
Cats that received more playtime mirroring hunting behaviors brought back 25 percent fewer kills. This percentage reflects a drop in the number of mammals brought back, but not birds, Science News reports. On the other hand, the puzzle feeder caused the cats to bring home more prey, and researchers speculate it may have been out of frustration from their inexperience with the puzzle, Gizmodo reports. Cats with the bright collars brought home 42 percent fewer birds, but the same amount of small mammals, reports Science News. Meanwhile, bells did not reduce kills.
"We were surprised diet change has such a strong effect. Nutrition seems to have some bearing on a cat's tendency to kill things, and some cats that hunt may need something extra," says Robbie McDonald, an ecologist at the University of Exeter and co-author of the study, to Science News.
Most cat foods contain high-quality proteins. However, they're often plant-based and may send cats in search of micronutrients missing from their cat food, Gizmodo reports.
McDonald and his team plan to further look into how cat predation on wildlife can be reduced by either combining two or more methods they investigated in their study, or analyzing exactly what it is nutritionally that cats crave from their kills, Gizmodo reports . The researchers hope that their work inspires cat-owners to use these less controversial methods to protect wildlife from their felines.
"We hope that owners of cats who hunt consider trying these changes," McDonald tells Science News. "It's good for conservation and good for cats."