FEATURE - Skyscrapers turn out lights to save migrating birds
Date: 01-Jun-01
Country: USA
Author: Andrew Stern
Each year about 100 million birds across the United States are killed in crashes into windows or die from exhaustion after becoming mesmerized by lighted buildings, scientists say.
"Any one building might be killing 2,000 birds a year," said Doug Stotz, an ornithologist at Chicago's Field Museum.
Now more than a dozen Chicago skyscrapers and lakefront buildings have turned off outdoor lights or closed window shades and drapes to reduce the toll on migratory birds. Their actions cut bird deaths by 75 percent or more, scientists say.
"Whether birds are striking buildings, communication towers, power lines, or hitting airplanes or getting whacked by cars, they are all mortality factors," said Al Manville, a wildlife biologist with the U.S. Fish and Wildlife Service.
"The most vulnerable are the 350 migratory species such as vireos, warblers, and thrushes," many already endangered, he said. "Pesticides, herbicides, even house cats kill many birds," he said, adding that thousands of songbirds would be spared if pet cats were kept indoors during migration season.
Some 5 billion migratory birds travel across the eastern half of the United States during spring and autumn migrations. They fly at night, avoiding airborne predators, and navigate by starlight, moonlight and geographical clues such as rivers and lake and ocean shorelines, scientists say.
BIRDS ARE CONFUSED
In a phenomenon that is not fully understood, the birds become confused by building lights, particularly on cloudy or misty nights. They circle like moths around a flame until they are exhausted, or crash into windows that either appear transparent or reflect the surrounding terrain or sky.
Some birds are fooled by mirror-glass skyscrapers along East Coast and Great Lakes flyways, both densely traveled routes between their winter havens in the tropics of Central and South America and their North American nesting grounds.
In Chicago, City Hall took up the crusade to darken the city's impressive skyline during bird migration season.
"Some buildings shine colored lights for the holidays, so we said, 'What about celebrating or recognizing migratory birds by dimming your lights?'" said Jessica Rio of Chicago's Department of the Environment.
"Before the program began there were a lot of dead birds on the roof during migration season - it was a decent cleanup job," said Roy Endsley, manager of the 65-storey Three-Eleven South Wacker tower.
He said few bird deaths occur now that the downtown tower's signature lighted crown has been doused for several weeks twice a year. And bird watchers have spotted 80 different species lingering in the small patch of greenery astride the building.
Birds not diverted to the city's concrete jungle find an oasis in its lakefront parks, though some fall prey to an increasing number of urbanized raptors including peregrine falcons and kestrels.
To provide the migrating birds a hiding place and food, the parks department adopted environmentalists' suggestions to plant more native trees and shrubs and delay grass mowing.
DRAWN INTO DEATH TRAPS
Sadly, migratory birds often fly thousands of miles, some using every ounce of energy to traverse natural barriers such as the Gulf of Mexico, only to be drawn into death traps by the lights and glass windows of urban sprawl, scientists say.
"If this were a well-recognized problem - if people saw dead birds lying at the entrance - I think that many architects would be persuaded to not use reflectorized glass," said Shankar Nair, chairman of the Council on Tall Buildings and Urban Habitat, a group of engineers and architects.
Windows are indispensable tools for architects, "bringing the outside in and the inside out" in daylight, and lighting illuminates the impressive skyline at night, Nair said.
"I don't think any architect wants to see his building blacked out when others are not," he said. But more Chicago building owners are seeing the light by shutti