(USA TODAY) -- That mouse carcass Kitty presents you with is just the tipof a very bloody iceberg. When researchers attached kittycams to house cats,they found a secret world of slaughter.

While only 30% of roaming house cats kill prey - two animalsa week on average - they are still slaying more wildlife than previouslybelieved, according to research from the University of Georgia.

Wildlife advocates say it is a frightening level of felinefoul play. Based on a U.S. house-cat population of 74 million, "catpredation is one of the reasons why one in three American birds species are indecline," says George Fenwick, president of American Bird Conservancy.

"The previous estimates were probably too conservativebecause they didn't include the animals that cats ate or left behind,"University of Georgia researcher Kerrie Anne Loyd says.

The cats brought home just under a quarter of what theykilled, ate 30% and left 49% to rot where they died.

The carnage cuts across species. Lizards, snakes and frogsmade up 41% of the animals killed, Loyd and fellow researcher Sonia Hernandezfound. Mammals such as chipmunks and voles were 25%, insects and worms 20% andbirds 12%. The researchers will present their findings this week at anEcological Society of America conference in Portland, Ore.

Seeking a window into the hidden lives of cats, theresearchers recruited 60 owners in the Athens, Ga., area. Each owner put asmall video camera mounted on a break-away collar on the cat in the morning andlet the cat out, then removed the camera and downloaded the footage each night.Each cat's activities were recorded for seven to 10 days. The cats usuallyspent four to six hours outside every day.

The researchers worked with the National GeographicCritterCam team, which builds tiny mobile data gathering systems to study wildanimal behavior. The cat cameras were the smallest they've made to date,National Geographic's Greg Marshall says.

Cats aren't just a danger to others, they're also a dangerto themselves. The cats in the study were seen engaging in such risky behavioras crossing roadways (45%), eating and drinking things they found (25%),exploring storm drains (20%) and entering crawl spaces where they could becometrapped (20%).

Male cats were more likely to do risky things than femalecats, and older cats were more careful than younger ones.

Written by Elizabeth Weise
USA Today & usatoday.com

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