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Why do cats kill small animals? A chemical analysis of their whiskers has the answer

Your cat is a cuddly little furball. He’s also a natural-born predator. Domestic cats are considered a globally invasive species, and one 2013 report found cats kill 1.4 to 3.7 million birds each year. Unfortunately, the news about your little sofa lion’s capabilities only gets grimmer from there. Cats may kill more than 20 billion mammals each year, like rats, squirrels, and rabbits. It may come as a surprise, especially if your sweet kitty happily purrs all day and snuggles you to sleep each night.

A new study of cat whiskers is providing more insight into why cats kill animals. Here’s what researchers found and what it teaches us about our feline friends.

a gray tabby cat hunting in grass

About the study

Dr. Martina Cecchiti and some fellow researchers knew that cats posed a danger to small animals that are vital for a functioning ecosystem, but they wanted to learn more about why cats kill animals. For example, are they hungry, lacking nutrition, or just hunting for fun?

The researchers asked parents of typically free-ranging cats who displayed hunting behaviors in Southwest England to participate. They clipped some of the cats’ whiskers.

The research team told each pet parent to remove anything that might tip off prey or make it harder for the cat to successfully catch an animal, like bells and collars that could alert a bird to the cat’s presence. The human participants took note of any game their kitty brought home for seven weeks.

The researchers sought to understand what interventions reduced predation, so they separated cats into trial groups and gave them a set of preventative measures to try. Some examples of these interventions included puzzle feeders, noise-making collars, high-protein foods, and active playtime. The kitties’ parents continued to collect any prey and freeze it. The goal was to help researchers determine the best ways to minimize cats’ hunting behaviors or, at the very least, the ability to kill small animals successfully.

The cats who had their whiskers clipped at the beginning of the study had them clipped again so researchers could analyze them. Why? The researchers wanted to evaluate the distribution of provided cat food and consumed wild prey. The scientists explained that when a cat eats, markers of that food show up in keratinous tissues like fur, claws, and whiskers. The whiskers could be collected and inspected with relatively little fuss.

Researchers freeze-dried the prey and food samples the study participants gave them, then ground them into powder. They analyzed the powder and whiskers to determine how much of a cat’s diet came from each food source.

Why cats kill small animals, according to scientists

Once researchers analyzed the data, they came to the conclusion that your cat hunts because she wants to and can, not because the food you give her lacks nutrients. Even if a cat successfully captured and consumed prey in the study, it was a tiny portion of their overall diet.

“The diet of domestic cats consists almost entirely of food provided by humans, with only 3-4% coming from captured prey,” the researchers wrote in the study. “This indicates that predatory behavior is likely a result of instinct or stimulation and not driven by dietary deficiency.” The takeaway? Cats in the wild hunt to eat, and Fluffy hunts due to those evolutionary instincts and just because it’s fun for her.

a longhaired black cat playing with a rope

What the research teaches us

First, there’s nothing wrong with your cat food, and you shouldn’t feel guilty when your cat “window shops” for birds from inside. You’re not depriving him of essential nutrients. Cats are natural hunters, and even thousands of years of domestication can’t eliminate their desire to catch prey.

Allowing a cat to hunt can damage the ecosystem, but you also likely want to keep your feline friend happy. The researchers found that the Birdsbesafe collar cover was the best method for reducing the consumption of wild prey. These collars come in bright collars that are easy for birds to spot, so your cat gets the thrill of the chase while the birds can fly away unscathed.

Other methods to reduce a cat’s hunting instinct included providing food with high meat content and offering objects for playtime. Engaging your cat in a rousing session with his favorite fish pole is a great way to bond and let him act like the tiny predator he is without actually killing anything.

Cats will be cats

Cats love hunting, but your pet cat doesn’t need to kill small animals to get nutrients. Scientists have found that even kitties who successfully catch prey still rely mainly on the food provided by their humans to survive. When cats hunt, it’s simply instinctual. Therefore, you can ditch the cat-parent guilt you feel about keeping your pet inside, and you don’t need to find new food. In fact, it’s better for the ecosystem if you find other ways to help your cat satisfy his needs. Engage your cat with toys, such as fishing poles and food puzzles, so that he can fulfill his drive to hunt without actually hurting another animal. If you’re concerned about your cat’s health or happiness, or if you need more advice about how to curb your kitty’s hunting habit, you can always talk to your vet.

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BethAnn Mayer
Beth Ann's work has appeared on and In her spare time, you can find her running (either marathons…
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