Cats kill billions of birds, mammals in U.S.

Outdoor cats account for the leading cause of death among both birds and mammals in the United States, according to a new study, killing anywhere between 1.4 billion and 3.7 billion birds each year.

The mammalian toll is even higher, concluded researchers from the Smithsonian Conservation Biology Institute and the U.S. Fish and Wildlife Service, ranging between 6.9 billion and 20.7 billion annually.

The analysis, published Tuesday in the journal Nature Communications, suggests feral and owned cats pose a far greater threat than previously thought. One study in 2011 estimated cats in the United States kill roughly half a billion birds annually.

Peter Marra, the paper’s senior author and a research scientist at the Smithsonian Conservation Biology Institute, said he and his colleagues “pulled together all the best estimates” from 90 different studies to reach their estimate, taking into account the difference in behavior between owned and unowned cats.

“I don’t think there’s ever been an attempt like this,” Marra said in a telephone interview, adding the new estimate is “conservative.”

Researchers estimate one pet cat kills between one and 34 birds a year, while a feral cat kills between 23 and 46 birds a year. As a result, the new study provides a wide range of the total bird death count. “It’s not a single number,” Marra said.

George Fenwick, president of American Bird Conservancy, said in a statement that the findings should serve as “a wake-up call for cat owners and communities to get serious about this problem before even more ecological damage occurs.”

“The very high credibility of this study should finally put to rest the misguided notions that outdoor cats represent some harmless, new component to the natural environment,” Fenwick said. “The carnage that outdoor cats inflict is staggering and can no longer be ignored or dismissed.”

Cats pose the greatest danger to birds and mammals living on islands, because there are fewer opportunities for these animals to escape. Cats are responsible for helping drive 33 species of birds, mammals and reptiles to extinction on islands, including the Stephens Island wren from New Zealand in the late 1800s, according to the International Union for Conservation of Nature.

Scientists have a hard time measuring the impact of cats on small mammals in the United States because they lack precise population counts for these species, Marra said.

“We don’t know how many Eastern cottontail rabbits are out there, and we don’t know how many chipmunks are out there,” he said.

By contrast, researchers estimate the United States is home to between 15 billion and 20 billion adult land birds. Cats kill about 10 percent of them each year, according to the analysis.

Marra and two other scientists, the Smithsonian Institute’s Scott Loss and Tom Will from Fish and Wildlife, conducted their analysis as part of a broader study of humans’ impact on bird mortality. Roughly 150,000 to 400,000 birds in the United States die in wind turbines, according to recent estimates, while between 10 million and 1 billon birds die annually after colliding into glass.

The fact that humans can take action to prevent some of these deaths — such as adopting policies to reduce feral cat populations and altering how wind turbines are designed — should provide some hope, Marra said.

“These are things that are reversible once we understand them,” he said. “That’s the important thing here.”

More in Local News

Former Monroe cop loses appeal on sex crimes conviction

Once a highly respected officer, he was found guilty of secretly videotaping his kids’ babysitter.

Derrick “Wiz” Crawford, 22, is a suspect in the homicide of his roommate. (Edmonds Police Department)
Roommate suspected in Edmonds killing found hiding in closet

Police had been searching for him for 10 days before locating him at a house in Everett.

Young woman missing from Mukilteo found safe

She called her parents and told them she was at a museum in Seattle.

Camano Island man gets 18 years for role in drug ring

He was convicted of helping lead a drug distribution network in four Washington counties.

Mom and brother turn in suspect in Stanwood robberies

The man is suspected of robbing the same gas station twice, and apologizing to the clerk afterward.

Lake Stevens man missing since beginning of January

Jason Michael Knox White hasn’t used his credit card or withdrawn money from his bank since then.

Navy to put filter in Coupeville’s contaminated water system

Chemicals from firefighting foam was found in the town’s drinking water.

Nichols Brothers Boat Builders apprentice Janette Alhanati (left) and journeyman Kurt Warwick construct wall panels for an upcoming boat project with Linblad Expedition Holdings. A federal grant from the Northwest Workforce Council will allow Nichols Brothers to add more apprentices to its workforce starting in January 2018.
Whidbey Island boatbuilder gets hiring boost

The grant from the Northwest Workforce Council will help expand the company’s apprenticeship program.

Video shows man suspected of attacking a woman in Edmonds

The man allegedly threw her on the ground, then ran away after the she began kicking and screaming.

Most Read