According to new research, cats are responsible for the deaths of billions of birds and rodents each year in the US.

Cats are responsible for the deaths of billions of birds and animals every year in the United States, a report has claimed.

According to the research published in the journal Nature Communications, the lethal felines kill between 1.4 and 3.7 billion birds and 6.9-20.7 billion mammals annually.

Experts insist that the new findings suggest that the wildlife death toll is much greater than previously believed.

The scientists behind the report claimed that although stray and feral cats were the worst offenders, domestic cats generally killed more than they took home with them.

Dr Pete Marra, an animal ecologist with the Smithsonian Conservation Biology Institute, said: "Our study suggests that they are the top threat to US wildlife.

"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," Marra added.

The study also revealed that 30 percent of the wildlife killed by domestic cats was eaten immediately but 49 percent was simply left to rot where it died.

An RSPCA spokeswoman said that a properly fitted collar and bell could reduce a cat's success when hunting by at least a third.

"To maintain the integrity of our ecosystems, we have to conserve the animals that play integral roles in those ecosystems," Dr George Fenwick, president of American Bird Conservancy, said.

"Every time we lose another bird species or suppress their population numbers, we're altering the very ecosystems that we depend on as humans."