Meatier meals and more playtime might reduce cats’ toll on wildlife

Surprisingly simple measures might keep domestic cats from killing a lot of wildlife.

Estimates vary, but it’s likely that billions of birds and mammals succumb each year to our outdoor-ranging feline friends (SN: 1/29/13). Calls to keep cats indoors are often contentious among cat owners, and cats can sometimes reject colorful collars or loud bells designed to make them more noticeable.

But a meat-rich diet or a few minutes of hunting-like play each day can significantly reduce the amount of wildlife they bring home, researchers report February 11 in Current Biology. 

Interventions that reduce cat predation and have buy-in from cat owners “are so important because we’re just decimating bird populations,” says Susan Willson, an ecologist at St. Lawrence University in Canton, N.Y., who wasn’t involved in the study. While preliminary, she says this study shows that “simply feeding your cat a high-meat diet might actually work.”

Most attempts to curb cats’ impact on wildlife have focused on restricting cat behavior and their ability to hunt. But Robbie McDonald, an ecologist at the University of Exeter in Cornwall, England, and his colleagues investigated the root of the problem: the urge to go out hunting in the first place. “We wanted to find out why well-fed cats might still kill wildlife,” he says.

The team reasoned this urge might stem from natural instincts to hunt, or from a need for cats to supplement their diet. Cats are carnivores, and some cat foods might not be meeting all a cat’s needs, McDonald says. If either of these influence hunting behavior, then perhaps beefing up the amount of meat in a cat’s diet or mimicking hunting behavior through play could fulfill those needs without the collateral damage to wildlife.

McDonald and his colleagues tested these new interventions on 355 domestic cats in 219 households in England’s southwest. Only known hunters were enrolled, and owners first tallied up every bird, mammal or other critter their cats brought home for seven weeks, to establish a baseline for each cat.

Owners then implemented one of a handful of interventions for six weeks: switching to a grain-free, high-meat commercially available food; playing for five to 10 minutes each day; putting their cat’s normal food in a puzzle feeder; and existing methods like bells or Birdsbesafe collars. Some owners didn’t change anything, but continued tracking their cats.

Cats fed the meat-rich diet brought home 36 percent less prey, on average, than they did before the diet change, the team calculated. For instance, a cat that normally brings home a daily catch would instead return about 20 critters a month. “This might not seem like very much,” McDonald says of the drop. But “a very large cat population means that if this average were applied across the board, it would result in very many millions fewer deaths.”

Felines treated to playtime, which consisted of owners getting their cats to stalk, chase and pounce on a feather toy and then giving cats a mouse toy to bite, returned 25 percent less prey, though that drop came mostly from mammals, not birds. Cats that started using puzzle feeders actually brought home more wildlife. Bells had no discernible effect, while cats fitted with Birdsbesafe collars brought home 42 percent fewer birds, but roughly the same number of mammals, which aligns with previous research.

“We were surprised diet change had such a strong effect,” McDonald says, in part because the cat’s pretreatment diets were all variable. “Nutrition seems to have some bearing on a cat’s tendency to kill things and some cats that hunt may need something extra” that’s provided by a meatier diet, he says. McDonald is already working to pinpoint what that extra something might be.

“It’s a robust study that I hope is followed up with more research,” says Willson, the St. Lawrence ecologist. Because the study focused on prey brought home, it could be missing wildlife killed and eaten or left outside, she says. 

The surest way to prevent cats from killing wildlife is to keep them indoors, McDonald says. While many cat owners care about wildlife, they also resist such restrictions as unnatural for their cat. But McDonald found these new interventions were less controversial. After the trial, 33 percent of participants reported they planned to continue feeding their cats meat-rich diets, and 76 percent reported they’d play more with their cats. 

“We hope that owners of cats who hunt consider trying these changes,” McDonald says. “It’s good for conservation and good for cats.”