Cats killing billions of animals in the US

Cats are one of the top threats to US wildlife, killing billions of animals each year, a study suggests.

The authors estimate they are responsible for the deaths of between 1.4 and 3.7 billion birds and 6.9-20.7 billion mammals annually.

Writing in Nature Communications, the scientists said stray and feral cats were the worst offenders.

However, they added that pet cats also played a role and that owners should do more to reduce their impact.

The authors concluded that more animals are dying at the claws of cats in the United States than in road accidents, collisions with buildings or poisonings.

The domestic cat's killer instinct has been well documented on many islands around the world.

Felines accompanying their human companions have gone on to prey on the local wildlife, and they have been blamed for the global extinction of 33 species.

The team said that "un-owned" cats, which they classified as strays, feral cats and farm cats, were killing about three times as many animals as pet cats. However, they said pet cats were still killing significant numbers of animals, and that their owners should do more to limit the impact.

Dr Marra said: "We hope that the large amount of wildlife mortality indicated by our research convinces some cat owners to keep their cats indoors and that it alerts policymakers, wildlife managers and scientists to the large magnitude of wildlife mortality caused by cat predation."

A spokeswoman for the UK's animal welfare charity the RSPCA said that a properly fitted collar and bell could reduce a cat's success when hunting by at least a third.