Pet cats have up to '10-times larger impact on wildlife than wild predators' © Roland Kays/North Carolina State University/PA

Pet cats have up to ‘10-times larger impact on wildlife than wild predators’

Hunting by pets can have a big effect on the local wildlife population, a new study has found.

  • Pet cats kill two to 10 times more wildlife than similar-sized wild predators.
  • Cats only hunt in a small area around their home, within a 100m radius, meaning the effect on wildlife is highly concentrated.
  • The researchers captured GPS data from 925 pet cats, and asked their owners to report how many animals they brought home.
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Domestic cats kill more prey in a given area than similar-sized wild predators, research suggests.

According to a new study, hunting by pets can have a big effect on the local wildlife population. Scientists say the effect is mostly concentrated around a cat’s home, as most of their movement is within a 100m radius. This usually encompasses a few gardens on either side.

The study indicates that pet cats kill two to 10 times more wildlife than the equivalent wild predator.

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Researchers from North Carolina State University and the North Carolina Museum of Natural Sciences worked with scientists from six countries to collect GPS cat-tracking data and prey-capture reports from 925 pet cats. Most of the animals came from the US, UK, Australia and New Zealand.

Lead author Roland Kays said: “Since they are fed cat food, pets kill fewer prey per day then wild predators, but their home ranges were so small that this effect on local prey ends up getting really concentrated.

“Add to this the unnaturally high density of pet cats in some areas, and the risk to bird and small mammal populations gets even worse. We found that house cats have a two- to 10-time larger impact on wildlife than wild predators – a striking effect.”

Researchers asked pet owners to track their cats to see where they went, and report on the number of prey they brought home. GPS trackers measured the distances travelled by the house cats which spent their days both indoors and outdoors.

Since they are fed cat food, pets kill fewer prey per day then wild predators, but their home ranges were so small that this effect on local prey ends up getting really concentrated
Professor Roland Kays

Prof Kays said: “We knew cats were killing lots of animals – some estimates show that cats in North America kill from 10 to 30 billion wildlife animals per year – but we didn’t know the area in which that was happening, or how this compared with what we see in nature.”

In the study, published in the Animal Conservation journal, scientists calculated the amount of prey killed per year by house cats and divided the number by the area in which the cats hunted. Some adjustments were made to the prey count as the animals do not necessarily take all their kills home.

According to the study, house cats killed an average of 14.2 to 38.9 prey per 100 acres, or hectare, per year. The study also showed that cats do much of their damage to wildlife in disturbed habitats, like housing developments.

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Study co-author Rob Dunn, William Neal Reynolds distinguished professor of applied ecology at NC State University, said: “Humans find joy in biodiversity, but we have, by letting cats go outdoors, unwittingly engineered a world in which such joys are ever harder to experience.”

Pet cats: should they be kept indoors?

For owners worried about wildlife, Scott Loss, associate professor of ecology, recommends keeping their pet cats indoors. Or, if they’re outdoors, to have them restrained in some way, either by installing ‘catios’ – outdoor cat enclosures that enable them to run around but separate them from wildlife – or even walking them on a lead.

“Often, those suggestions don’t go over well with cat owners. They say ‘my cat isn’t a problem’ so they don’t think it’s worth restraining them.” says Loss. 

Otherwise if you want a pet cat, but can’t put up with its murderous tendencies, Bradshaw suggests getting a kitten who has never been out, or a cat that’s always been kept indoors. Bringing a cat inside who has previously explored the Great Outdoors can have its challenges, and their individual personalities will determine how well they’ll adapt to life in captivity.