By Chuck Raasch USA Today

Cats that live in the wild or pets allowed to roam outdoors kill from 1.4 billion to as many as 3.7 billion birds in the continental U.S. each year, says a new study that escalates a decades­old debate over the feline threat to native animals.

The estimates are much higher than the hundreds of millions of annual bird deaths previ­ously attributed to cats.

'I was stunned,' said ornithologist Peter Mar­ra of the Smithsonian's Conservation Biology In­stitute. He and Smithso­nian colleague Scott Loss, and U.S.Fish and Wildlife Service biologist Tom Will, conducted the study.

Larger threat It's part of a three­year Fish and Wildlife Service-funded effort to estimate the number of birds killed by predators, chemicals and in colli­sions with wind genera­tors and windows. About a third of the 8OO species of birds in the U.S. are en­dangered, threatened or in significant decline, ac­cording to the nonprofit American Bird Conser­vancy.

For years, bird lovers and cat lovers have clashed over whether outdoor cats, not native to the U.S., should be euth­anized or allowed to roam free in managed pro­grams that include neu­tering.

'Our findings suggest that free-ranging cats cause substantially greater wildlife mortal­ity than previously thought and are likely the single greatest source of anthropogenic mortality for U.S. birds and mam­mals,' Marra and his co­authors conclude. 'Scien­tifically sound conserva­tion and policy interven­tion is needed to reduce this impact.'

Trap-neuter-return

The study is critical of the trap-neuter-return policy advocated by Al­ley Cat Allies and other defenders of free-roam­ing cats. The goal of the policy is to gradually re­duce outdoor cat popula­tions while avoiding widespread euthanasia policies in animal shel­ters.

But the new study calls the trap-neuter-re­turn policy 'potentially harmful to wildlife popu­lations' because it leaves so many predators in the wild. The authors also say the policy is often put in place by cities and coun­ties without 'widespread public knowledge' and without studies on the ef­fects of large feral cat populations on the envi­ronment.


Allies weigh in

Cat defenders say that the new estimates won't change their belief that cats are scapegoats for bird habitat loss, chemi­cals used in fertilizers and insecticides, and col­lisions with man-made objects. 'Human impact
FIGURES TO KNOW

The study also says that from 6.9 billion to as many as 20.7 billion mammals — mainly mice, shrews, rabbits and voles — are killed by cats annually in the lower 48 states.

is the real threat' to birds, says Becky Robin­son, president of Alley Cat Allies, a nonprofit that defends outdoor cats. She says the trap­neuter- return policy is growing because people see it as a way to protect birds without killing cats. George Fenwick, president of the Ameri­can Bird Conservancy, says the issue is not cats versus birds but 'a run­away and invasive popu­lation of cats' that are killing too many birds.

Fenwick says the study gives his side pow­erful evidence that trap­neuter- return isn't work­ing, and to push for more responsible cat-owner­ship policies across the country.

http://www.usatoday.com/story/news/nation/2013/01/29/cats-wild-birds-mammals-study/1873871/