http://www.nytimes.com/2013/01/30/science/that-cuddly-kitty-of-yours-is-a-killer.html?emc=eta1

January 29, 2013
That Cuddly Kitty Is Deadlier Than You Think
By NATALIE ANGIER

For all the adorable images of cats that play the piano, flush the toilet, mew melodiously and find their way back home over hundreds of miles, scientists have identified a shocking new truth: cats are far deadlier than anyone realized.
In a report that scaled up local surveys and pilot studies to national dimensions, scientists from the Smithsonian Conservation Biology Institute and the Fish and Wildlife Service estimated that domestic cats in the United States — both the pet Fluffies that spend part of the day outdoors and the unnamed strays and ferals that never leave it -- kill a median of 2.4 billion birds and 12.3 billion mammals a year, most of them native mammals like shrews, chipmunks and voles rather than introduced pests like the Norway rat.

The estimated kill rates are two to four times higher than mortality figures previously bandied about, and position the domestic cat as one of the single greatest human-linked threats to wildlife in the nation. More birds and mammals die at the mouths of cats, the report said, than from automobile strikes, pesticides and poisons, collisions with skyscrapers and windmills and other so-called anthropogenic causes.

Peter Marra of the Smithsonian Conservation Biology Institute and an author of the report, said the mortality figures that emerge from the new model "are shockingly high."

"When we ran the model, we didn't know what to expect," said Dr. Marra, who performed the analysis with his colleague, Scott R. Loss, and Tom Will of the Fish and Wildlife Service. "We were absolutely stunned by the results." The study appeared Tuesday in the journal Nature Communications.

The findings are the first serious estimate of just how much wildlife America's vast population of free-roaming domestic cats manages to kill each year.

"We've been discussing this problem of cats and wildlife for years and years, and now we finally have some good science to start nailing down the numbers," said George H. Fenwick, the president and chief executive of the American Bird Conservancy. "This is a great leap forward over the quality of research we had before."

In devising their mathematical model, the researchers systematically sifted through the existing scientific literature on cat-wildlife interactions, eliminated studies in which the sample size was too small or the results too extreme, and then extracted and standardized the findings from the 21 most rigorous studies. The results admittedly come with wide ranges and uncertainties.

Nevertheless, the new report is likely to fuel the sometimes vitriolic debate between environmentalists who see free-roaming domestic cats as an invasive species — super predators whose numbers are growing globally even as the songbirds and many other animals the cats prey on are in decline — and animal welfare advocates who are appalled by the millions of unwanted cats (and dogs) euthanized in animal shelters each year.

All concur that pet cats should not be allowed to prowl around the neighborhood at will, any more than should a pet dog, horse or potbellied pig, and that cat owners who insist their felines "deserve" a bit of freedom are being irresponsible and ultimately not very cat friendly. Through recent projects like Kitty Cams at the University of Georgia, in which cameras are attached to the collars of indoor–outdoor pet cats to track their activities, not only have cats been filmed preying on cardinals, frogs and field mice, they've been shown lapping up antifreeze and sewer sludge, dodging under moving cars and sparring violently with much bigger dogs.

"We've put a lot of effort into trying to educate people that they should not let their cats outside, that it's bad for the cats and can shorten the cats' lives," said Danielle Bays, the manager of the community cat programs at the Washington Humane Society.

Yet the new study estimates that free-roaming pets account for only about 29 percent of the birds and 11 percent of the mammals killed by domestic cats each year, and the real problem arises over how to manage the 80 million or so stray or feral cats that commit the bulk of the wildlife slaughter.

The Washington Humane Society and many other animal welfare organizations support the use of increasingly popular trap-neuter-return programs, in which unowned cats are caught, vaccinated, spayed and, if no home can be found for them, returned to the outdoor colony from which they came. Proponents see this approach as a humane alternative to large-scale euthanasia, and they insist that a colony of neutered cats can't reproduce and thus will eventually disappear.

Conservationists say that, far from diminishing the population of unowned cats, trap and release programs may be making it worse, by encouraging people to abandon their pets to outdoor colonies that volunteers often keep lovingly fed.
"The number of free roaming cats is definitively growing," Dr. Fenwick of the bird conservancy said. "It's estimated that there are now more than 500 TNR colonies in Austin alone."

They are colonies of subsidized predators, he said, able to survive in far greater concentrations than do wild carnivores by dint of their people-pleasing appeal. "They're not like coyotes, having to make their way in the world," he said.

Yet even fed cats are profoundly tuned to the hunt, and when they see something flutter, they can't help but move in for the kill. Dr. Fenwick argues that far more effort should be put into animal adoption. "For the great majority of healthy cats," he said, "homes can be found." Any outdoor colonies that remain should be enclosed, he said. "Cats don't need to wander hundred of miles to be happy," he said.

http://www.bbc.co.uk/news/science-environment-21236690

BBC - 29 January 2013
Cats killing billions of animals in the US

By Rebecca Morelle Science reporter, BBC World Service 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.

But their impact on mainland areas has been harder to chart.

To find out more, researchers from the Smithsonian Conservation Biology Institute (SCBI) and the US Fish and Wildlife Service carried out a review of studies that had previously looked at the predatory prowess of cats.

Their analysis revealed that the cat killings were much higher than previous studies had suggested: they found that they had killed more than four times as many birds as has been previously estimated.

Birds native to the US, such as the American Robin, were most at risk, and mice, shrews, voles, squirrels and rabbits were the mammals most likely to be killed.

Dr Pete Marra from the SCBI said: "Our study suggests that they are the top threat to US wildlife."

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 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.