Why windows pose a clear and present danger to birds

When you hear a thud against your window, more often than not it’s sad news. A bird has flown headlong into the glass, often with fatal results.

People often wonder: If I can see the glass, why can’t the bird?

“What it comes down to is birds can’t see glass the way humans can,” said Kim Roth Nelson, who has a masters degree in biology with an emphasis in bird-window collision prevention.

When they look at a window they’ll see a reflection of trees, she said. Or they think there’s a passageway they can fly through.

“It’s a big problem, absolutely,” said Jessie Paolello, clinic manager at the Sarvey Wildlife Care Center in Arlington. She estimates that they treat “in the hundreds if not more” every year for injuries such as broken bones and head trauma. “They come in every day.”

Most of the injuries are to songbirds, she said. But some raptors, such as Cooper’s hawks and American kestrels, which prey on birds, also are injured by window hits.

These head-on collisions with windows are roughly estimated to kill from 365 million to nearly a billion birds each year in the United States.

When collisions with buildings, cars and other structures are added in, that number is estimated to climb to 1.5 billion birds killed annually in North America, according to a study published last year in the online scientific journal PLOS.

This at a time when North American bird populations have declined by an estimated 3 billion birds since 1970, according to the journal Science.

In Western Washington, hummingbirds, thrushes and sparrows are among the most likely to be injured or killed by bird-window collisions.

Although applying a hawk decal to windows is a common method of trying to prevent collisions, it’s not necessarily effective.

“The bird will try to fly around it and still hit the glass,” Nelson said.

Not surprisingly, large windows present more of an accident hazard than small ones. And the more glass you have in a home, the more potential for collisions you have, she said.

Bird feeders can make matters worse. Try to post them less than 3 feet from a window — enough to slow their momentum if they hit the glass — or more than 30 feet away.

Bird feeders can create another problem. Cooper’s hawks find them an all-too-convenient place to stalk birds, chase them into the glass and then eating them, Nelson said.

Paolello said that people who find an injured bird on the ground and it doesn’t move when you approach, gently cover the bird with a pillow case or towel and put it in a shoe box.

“No food, no water and keep it in a warm, dark, quiet place,” she said.

Sometimes all birds need is an hour or two to recover and get their bearings. But serious injuries need to be treated at a facility like the Sarvey center.

Sometimes people arrive at Sarvey holding an injured bird in their hands, significantly increasing the stress in an already injured bird.

“Remember when you go to pick up an animal, they think it’s a predator,” Paolello said.

Bird-window collisions are often associated with skyscrapers. But the problem also frequently happens close to home.

“People have no clue how much of an issue it is in a residential house,” Nelson said. ”It’s just as significant in homes because it just adds up.”

Sharon Salyer: 425-339-3486 or salyer@heraldnet.com

What you can do

Here are some steps people can take to try to reduce bird injuries and deaths from collisions with windows:

• Set window blinds down, but open. The inch or so between each slat isn’t enough space for a bird to think it can fly through the space.

• Window treatments can be applied, such as fine nylon monofilament lines, CollidEscape, a window film, or dots and horizontal patterns.

• More information is available at the American Bird Conservancy website at tinyurl.com/birds-glass.

If you go

Avian conservationist Kim Roth Nelson will discuss window treatments used in preventing bird-window collisions during a meeting of the Whidbey Audubon Society at 7:30 p.m. Feb. 13 at the Unitarian Universalist Congregation meeting hall in Freeland, 20103 State Route 525. More at www.whidbeyaudubon.org.

This story has been modified to correct the safe distance for placement of bird feeders near windows.