'Stone-cold serial killers': Domestic cats slaughter billions upon billions of animals in US every year

They’re cuddly, adorable and the most reliably popular thing on the internet, but it turns out cats are also stone-cold serial killers.

A new study published by the journal Nature Communications has found that domestic cats slaughter billions of birds and small mammals in the US every year.

Scientists from the Smithsonian Conservation Biology Institute and the US Fish and Wildlife Service compiled nationwide data from a number of local surveys and pilot studies, to conclude that cats are responsible for the deaths of up to 3.7bn birds and 20.7bn small mammals every 12 months, including mice, voles, rabbits and shrews.

“The magnitude of wildlife mortality caused by cats that we report here far exceeds all prior estimates,” the study, which set out to estimate the number of animals killed as the result of human activity, concluded.

It positioned felines as the probable top human-linked threat to wildlife in North America. More birds and mammals die at the paws of cats than are killed by cars, chemicals or collisions with man-made structures.

The researchers estimated that US cat-owners account for around 84 million cats, which each kill between four and 18 birds per year, and between eight and 21 small mammals. However, the death counts racked up by domestic cats pales in comparison with that of feral cats, which the report suggests slay up to 46 birds and 338 small mammals each, annually. There are thought to be 30-80million such cats living wild in the US.

During an August 2012 study by the University of Georgia, researchers attached miniature video cameras to 60 cats to monitor their daily routines; they found that the felines typically spent one third of every day killing small animals. One of the new report’s authors, Dr Peter Marra of the Smithsonian Conservation Biology Institute, told NPR that he and his colleagues were stunned by the scale of the slaughter. Cats hunting, he said, “could be causing some wildlife populations to decline in some areas.”

The study recommends “conservation and policy intervention” in order to reduce the environmental impact of the bloodthirsty pets. Animal welfare groups advocate so-called trap-neuter-return (TNR) programmes: instead of being euthanized, feral cats are vaccinated, neutered and returned to the streets unable to reproduce. But conservationists claim this can exacerbate the problem by encouraging cat-owners to abandon unwanted cats to the growing number of outdoor cat colonies. The study found that TNR programmes are “potentially harmful to wildlife populations” because they leave so many murderous felines in the wild.

New Zealand economist and environmentalist Gareth Morgan has proposed more drastic measures. On his website garethsworld.com/catstogo, Mr Morgan claims, “That little ball of fluff you own is a natural born killer.” He urges cat owners to neuter their pets and resist the temptation to add any more to their households. He has also called on his fellow New Zealanders to set cat traps across the country to catch stray felines so they can be put down.