January 29, 2013
That Cuddly Kitty Is Deadlier Than You Think
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.
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
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
"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
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."
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
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
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
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
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.
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.
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.
BBC - 29
Cats killing billions of animals in the US
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
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.
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
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
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.