Cats are born hunters. So hopefully you’ve come to terms with the gifts of dead mice and birds little Fluffy periodically brings you.

After all, that’s what they do, right?

But the sheer scale of the slaughter may well cause you to raise any eyebrow.

catbird

Cats in the US are killing billions of birds and mammals a year

In the United States alone, cats are responsible for killing between 1.4 – 3.7 billion birds and 6.9 – 2.7 billion mammals a year.

This mind-boggling level of bloodlust – carried out by domestic animals, ferals and strays is the subject of a scientific paper published in the journal Nature.

Entitled “The impact of free-ranging domestic cats on wildlife of the United States”, the paper ominously states:

"Our findings suggest that free-ranging cats cause substantially greater wildlife mortality than previously thought and are likely the single greatest source of anthropogenic mortality for US birds and mammals. Scientifically sound conservation and policy intervention is needed to reduce this impact."

It adds that more animals are dying at the paws of cats in the country than in road accidents, collisions and poisonings.

The research, which was carried out jointly by scientists from the Smithsonian Conservation Biology Institute and the US Fish and Wildlife Service, found previously “negligible” cat kill numbers had been largely underestimated.

"The magnitude of wildlife mortality caused by cats that we report here far exceeds all prior estimates," said the paper.

American Robins, mice, shrews, vole, squirrels and rabbits are at the highest risk of being killed, the study claims.

american robin

At risk: The American Robin is at a high risk of being killed by cats

According to the BBC, felines have already been blamed for the global extinction of 33 species.

Cats without owners are being held accountable for most of the deaths. There are about 30 million to 80 million feral cats in the US, each of which can kill upwards of 200 mammals a year alone, the study reported.

It suggests taking measures such as limiting or preventing cats’ access to the outdoors.

Britain’s RSPCA charity suggests a bell on a cat’s collar could reduce its success in hunting by up to a third.

The report comes on the back of an interview with prominent economist and environmentalist Gareth Morgan, who wants residents in his native New Zealand to neuter their pets and start turning over strays to be euthanized.

In an interview with the New York Times, Morgan ignited controversy with his suggestion that cats should be gradually eradicated from his country.

Morgan claims that the feline is a "friendly neighborhood serial killer" that poses a serious threat to New Zealand's native birds and other animal species.

Speaking to the Atlantic, Morgan lays out his plans to eliminate New Zealand’s cat population in four simple steps.

He added:

"Neutered cats still kill for pleasure, and unless research has shown that neutering projects fail to reduce the size of feral cat colonies materially -- the problem being that getting 100% neutering coverage is too expensive for people and so they disobey such laws -- abandoned kitten litters and feral populations actually rise. Birds are only one of the species at risk, we have heaps of unique skunks, geckos, and insects that also are under siege from the cats humans have introduced to these islands."

They may be bloodthirsty, but they can be cute...

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  • Two stray kittens pose for a photograph at Battersea Dogs and Cats Home on August 18, 2009 in London, England. Battersea Dogs and Cats Home is seeing a sharp rise in the number of cats requiring a home with 143 of the 145 shelter's pens full. (Photo by Dan Kitwood/Getty Images)

  • Milly, a 13-week-old kitten waits with her brother Charlie (L) to be re-homed at The Society for Abandoned Animals Sanctuary in Sale, Manchester which is facing an urgent cash crisis and possible closure on July 27, 2010 in Manchester, England. (Photo by Christopher Furlong/Getty Images)

  • A kitten plays with a squirrel, which was rescued off the streets in Envigado, Antioquia Department, Colombia, on February 16, 2010. (RAUL ARBOLEDA/AFP/Getty Images)

  • Blondie, a bichon dog, looks at her adopted ten day old kitten, Yako, which was found in a rubbish bin, in Rabat 24 April 2001. Although the dog has had no pups of her own, she has no trouble feeding the kitten. (A DA/AFP/Getty Images)

  • A kitten is pictured on December 5, 2009 during a cat exibition in Moscow. (NATALIA KOLESNIKOVA/AFP/Getty Images)

  • A stray kitten is posed for a photograph at Battersea Dogs and Cats Home on August 18, 2009 in London, England. Battersea Dogs and Cats Home is seeing a sharp rise in the number of cats requiring a home with 143 of the 145 shelter's pens full. (Photo by Dan Kitwood/Getty Images)

  • A cat and her kitten play with a squirrel, which was rescued off the streets, in Envigado, Antioquia Department, Colombia, on February 16, 2010. (RAUL ARBOLEDA/AFP/Getty Images)

  • Kittens are pictured in a bucket, before the arrival of Britain's Camilla, the Duchess of Cornwall, at Battersea Dogs and Cats Home, in London on October 27, 2010. The Duchess opened the new cattery during her visit to the animal refuge, which is celebrating it's 150th anniversary this year. (Chris Jackson/AFP/Getty Images)

  • A volunteer displays a newly-born cat delivered by a rescued stray cat at the home of cat lover Duo Zirong on July 10, 2007 in Shanghai, China. (Photo by China Photos/Getty Images)

  • Two less than a week old kittens of a jungle cat (lebis Chaus) lie inside the forest department office in Mumbai, 11 June 2007. Three abondoned kittens, found in the jungles of Aarey milk colony, on the outskirts of the city, were later handed over to the forest authorities, likely to be released in the Borivali national park in Mumbai. (PAL PILLAI/AFP/Getty Images)

  • Boggles, a stray kitten, one of the lucky animals at the Barnes Hill RSPCA Animal Rescue Centre, has found a caring home on 4 April 2007, Birmingham, England. (Photo by Christopher Furlong/Getty Images)

  • Milly, a 13-week-old kitten looks through the glass of her pen as she waits to be re-homed at The Society for Abandoned Animals Sanctuary in Sale, Manchester, which is facing an urgent cash crisis and possible closure on July 27, 2010 in Manchester, England. (Photo by Christopher Furlong/Getty Images)