how many birds are killed by cars

If only birds had air bags. A new study shows that crashes with cars and trucks kill as many as 340 million birds on U.S. roads every year — a much higher toll than bird deaths from many other human activities.

Hunters bagged a mere 19 million U.S. ducks and geese in 2012, according to federal statistics, and a quarter-million to a half-million birds a year die after hitting wind turbines. Among well-studied causes of death tied to humans, only cats and collisions with buildings lead to more bird deaths than traffic does, the study says.

“We dont really pay attention to or talk much about this issue of vehicle collisions. … Were all used to driving,” says Cornell Lab of Ornithologys Amanda Rodewald, whos not affiliated with the study. But the new estimates show the toll of vehicles is “pretty staggering,” she says. “I had no idea.”

To compile a nationwide estimate of avian road kill, the studys authors extrapolated from 13 small-scale surveys of birds that died after being hit by vehicles. The results show that 89 million to 340 million birds suffer fatal injuries from vehicle encounters annually, a range that accounts for dead birds taken by scavengers, carcasses missed by researchers and other uncertainties, the researchers report in an upcoming issue of The Journal of Wildlife Management. Previous research had pegged bird deaths from vehicles at 60 million to 80 million.

The new study is “the most comprehensive analysis … to date,” statistician Wally Erickson of Western Ecosystems Technology, an environmental consulting group, says via e-mail. The numbers are probably in the right ballpark and show that traffic is one of the bigger human-caused killers of birds, he says.

Higher speed limits, wider roads and high bird populations may help make some roads especially deadly, says study author Scott Loss of Oklahoma State University, who worked with scientists from the U.S. Fish and Wildlife Service and the Smithsonian Migratory Bird Center. According to one study that Loss and his colleagues relied on, some 500 birds a year died on a two-mile stretch of highway through a Florida wildlife refuge. Many wouldve been tiny sparrows or warblers that drivers may not have even noticed.

“Everyone whos spent significant time in a car has probably hit a bird,” Loss says, confessing that he has done so himself and was a passenger in a car when a bird struck the windshield “like a rock hitting the window.”

Barn owls seem particularly marked for doom in Loss analysis. Now threatened or endangered in a number of states where they were once common, barn owls accounted for a large proportion of the deaths across the surveys Loss and his colleagues used for their analysis. One of those surveys estimated that as many as 1,500 barn owls a year died along a 150-mile stretch of interstate highway in Idaho – a death rate high enough to wipe out the local population.

Powerful headlights shining into the owls sensitive eyes might blind the birds or even cause them to freeze, explains Arkansas State Universitys Than Boves, an author of the barn owl study. While other owls sit safely on perches to look for food, barn owls hunt on the wing, potentially making them more vulnerable. Their vulnerability became clear to Boves when, in one day, he collected more than 100 dead barn owls.

The number was “overwhelming,” he says. “They werent sick, they werent starving. They were seemingly healthy animals that werent up to the challenge of dodging a whole lot of high-speed traffic at night.”

Strong headlights shining into the owls’ delicate eyes could blind them or even cause them to freeze, according to Than Boves of Arkansas State University, who wrote the study on barn owls. Barn owls hunt on the wing, which may make them more vulnerable than other owl species, while other owl species hunt safely from perches. Boves realized how vulnerable they were when he gathered over 100 dead barn owls in a single day.

The number was “overwhelming,” he says. “They werent sick, they werent starving. These appeared to be healthy animals, but they weren’t prepared to handle the nighttime traffic at high speeds. “.

According to statistician Wally Erickson of Western Ecosystems Technology, an environmental consulting firm, the new study is “the most comprehensive analysis… to date.” He says this via email. According to him, the data indicates that one of the main causes of bird deaths caused by humans is traffic.

Barn owls seem particularly marked for doom in Loss analysis. Barn owls accounted for a significant percentage of the deaths across the surveys used by Loss and his colleagues for their analysis, and they are now threatened or endangered in several states where they were once common. According to one of those surveys, a 150-mile stretch of Idaho’s interstate highway is home to up to 1,500 barn owl deaths annually, which would be enough to wipe out the local population.

If only birds had air bags. According to a recent study, up to 340 million birds are killed in collisions with cars and trucks on U S. roads each year, a mortality toll far greater than that of birds lost to numerous other human endeavors.

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Some species and their human companions won’t find this very consoling, as it appears that different birds are more or less vulnerable than others. For example, barn owls appear to be very prone to collisions. It pleased me to discover that the invasive European starling was also vulnerable. Sadly, it doesn’t appear that the house sparrow, a major threat to native birds, is in danger.

Motor vehicles whack more birds than all other hazards combined. However, due to their small size, it is challenging to obtain a precise count. If you hit a moose, you’ll probably stop and notify the appropriate law enforcement, conservation, and insurance authorities. Hit a bird and you might not even notice. However, scientists from the United States and the Smithsonian Conservation Biology Institute S. After reviewing the literature, the Fish and Wildlife Service estimated that between 89 million and 340 million people die in car crashes in the United States and 13 million in Canada.

One study hints that birds may be evolving to avoid collisions. The authors observed that cliff swallows killed by cars had longer wings than the swallows that survived. They speculate that this could be an example of survival of the fittest, because shorter wings enable these birds to turn more sharply, thereby avoiding a collision with fate.

Some who enthusiastically accept evolution may use this information as a justification to do nothing about bird mortality—the same geniuses who don’t worry about global warming because, well, Earth was hotter 65 million years ago—while others who reject the theory may argue that birds cannot adapt to their environment.

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