The Biggest Threat to U.S. Wildlife? Cats

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Earlier this month a New Zealand economist named Gareth Morgan made plenty of enemies among cat lovers by insisting that mankind needed to ditch its feline friends before they decimate local bird and animal species.

According to a new study, published Jan. 29 by the journal Nature Communications, things may be even worse than Morgan thought.  Cats are apparently responsible for killing birds and mammals on a massive scale. Based on a systematic review and quantitative estimates never before conducted in the mainland U.S., researchers found that house cats were responsible for the deaths of between 1.4 and 3.7 billion birds and between 7 and 20 billion mammals each year.

The cute, purring bundles of fur have long been recognized for their killer instinct and excellent hunting ability, and have been blamed for the global extinction of up to 33 species, reports the BBC.

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The new research, by scientists at the Smithsonian Conservation Biology Institute (SCBI) and the U.S. Fish and Wildlife Service, challenges previously held assumptions about the volume of animals killed by cats. “For the last 20, 30, 40 years the number that has been batted around as a max was about 500 million,” said Peter Marra, one of the senior authors behind the study, to National Geographic.

The authors discovered that the majority of kills could be attributed to ownerless cats, including barn cats, strays and feral colonies. The research showed that the animals largely prey on non-native mice and rats in densely populated urban areas, while in rural areas they target mice, shrews, voles, squirrels and even rabbits.

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Faced with the staggering numbers, the study’s authors have gone so far as to suggest that cats are “likely the single greatest source of anthropogenic mortality for U.S. birds and mammals.”

According to Reuters, domestic cats are classified among the 100 worst non-native invasive species in the world. The authors suggest that owners could do more to limit the impact of their pets: “A major reason for the current nonscientific approach to management of free-ranging cats is that the mortality from cat predation is often argued to be negligible compared with other (human-caused) threats.”

(MORE:  New Zealand Economist: Abolish Pet Cats to Save Birds )

But it will be difficult convincing American cat lovers of that. Cat ownership has risen from about 56 million in the mid-1990s to 80 million today. The American Cat Fanciers Association also questioned the findings. “Yes, they’re going to catch the occasional bird. But I don’t personally believe they’re responsible for mass death and destruction,” Carol Barbee, president of the association, said to Reuters.

MORE: Killer Kitties: Study Proves They’re Not as Innocent As They Look