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Windows and birds are a bad pairing 鳥兒最忌玻璃窗
« on: Dec 20th, 2004, 10:17am » |
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Windows and birds are a bad pairing
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Environment
It's a stomach-turning sound to anyone who's seen or heard a bird fly into a window at full tilt. Birds can't distinguish glass from open air, and that lack of judgment can injure or kill them.
No one knows how many birds whack into windows each year, but researcher Daniel Klem Jr. estimates the U.S. death toll at 100 million to 1 billion. That's as much as 5 percent of the bird population after the breeding season, and he suspects the actual number is even higher.
"Almost every structure on this planet has a piece of glass in it," he said, and each of those windows is a potential hazard to birds.
Klem, an ornithologist at Muhlenberg College in Allentown, Pa., based his estimate on research indicating one to 10 birds are killed each year for each building in this country, on average. And that doesn't count all the birds that end up with sore noggins or battered beaks from their non-fatal run-ins.
The problem, Klem said, is that birds don't perceive glass as an object. They see the sky reflected in a window, or they spot habitat through another window beyond, and into the glass they go.
Bird watcher Bill Thompson III has seen as many as five birds a day killed against the windows of his house, which sits on a ridge in a rural area in southeastern Ohio. His wife has a windowed studio that overlooks a brushy area, and especially during spring when the young birds are starting to fly, "we get thunk, thunk, thunk, thunk," said Thompson, editor of the magazine Bird Watchers Digest and a director of the Ohio Ornithological Society.
About a quarter of North American bird species have been known to fly into windows under a variety of circumstances, Klem has written. Some are trying to outrun a predator. Some are migrating. Others are looking for food or shelter.
Most strikes happen in winter, he said, when birds visit feeders in large numbers and often run into windows on their way to or from feeding stations. The problem gets the most attention during spring and fall migrations, however, because window accidents and their victims are most noticeable then.
Mating season is a time for a less dangerous kind of bird strike, when a male bird -- often a cardinal or robin -- sees a reflection of itself and thinks it's competition, said Damon Greer, a wildlife biologist with the Ohio Department of Natural Resources' Division of Wildlife. The bird will peck at the glass persistently to try to get at the intruder, sometimes for weeks on end. The bird rarely suffers anything worse than the occasional bloodied bill, Greer said, but the humans on the other side of the window can be driven to distraction.
Klem has argued for changes in building design to reduce bird strikes, including angling first-floor windows downward so they reflect the ground instead of the sky. So far, he said, he's gotten little heed from the building industry.
That could be changing, though. Audubon magazine wrote in its March issue that Klem's work has influenced construction projects including a science building at Swarthmore College, which will have windows with dots of opaque glass to discourage bird strikes. And the New York City Audubon Society is campaigning for bird-friendly design in any buildings that rise on the World Trade Center site.
In the short term, however, challenges remain. Thompson, for example, tried to have windows installed at a downward angle on a construction project at his farm and discovered that doing so would void the manufacturer's warranty.
Experts offer other suggestions for preventing bird strikes, such as stretching netting over windows to cushion the blow or hanging objects just outside to break up the birds' view.
Thompson believes they're useful at least as short-term measures for times when bird strikes are prevalent, such as migration.
"There are some drawbacks to every single one of them," he said. "You have to balance utility with making them [windows] as safe as possible for birds."
Copyright 2004, Chicago Tribune. All Rights Reserved.
Chicago Tribune
(摘自芝加哥論壇報 Chicago Tribute，Webcreeper 摘譯)
沒有人知道每年有多少雀鳥撞到玻璃窗上，美國研究員 Daniel Klem Jr. 估計單在美國便有一億到十億，約佔繁殖期後雀鳥數目的百分之五，而實際的數字 可能會更多。Klem 的估計假設美國國內每幢建築物平均撞死一到十隻鳥，但沒有致命的事件不計。
紀錄中大約有四分之一的北美鳥種曾撞到玻璃窗上，牠們可能在逃避天敵，或者在 遷徙途中，也可能正在找尋食物或停棲的地方。大部份的撞窗事件在冬季發生，在 鳥兒往返喂食器途中，但是最引人注目的則是春秋遷徙時發生的意外。
Klem 呼籲建築界改善設計以減少撞窗事件，包括將門上的玻璃稍稍向下傾斜，讓鳥兒見 到地面的而不是天空反射，可惜暫時未能成功。但是美國國內已開始有人採納防止 這些意外的設計，美國Audubon 鳥類學會更倡議在世貿遺址重建的大廈要加入相關措施。其他防止撞窗事件的方法包括在窗前架設細網以減低衝擊，或者在窗前放置一些物件去阻擋鳥的視線，這些方法最少可以在遷徙季節等高峰期減少意外。
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