BIRD COLLISION DEATHS: WINDOW KILLS

A small fraction of the tragic death of migratory birds from building collisions. (Photo: Jim Robertson). SOURCE: FLAP

This is the essence of a story in the New York Times which shocked and intrigued The Generalist.

Up to nine million birds a year are killed in Toronto by crashing into glass-fronted skyscrapers. The city, on the shore of Lake Ontario is in the path of several major bird migration routes. The glass facades reflect the sky or the surrounding trees, disorientating the birds who head for this mirage at high speed and end up maimed or dead on the pavement below.

So many birds – mainly songbirds - die in this way that volunteers from the Fatal Light Awareness Program (FLAP), founded in 1993, mount daily patrols to collect dead and injured birds in the city’s financial district. FLAP’s founder Michael Mesure once collected 500 dead birds in a single day.

 

Birds collected after colliding with buildings, Toronto 2009, by Kenneth Herdy, Source: FLAP

There have been developments since this story was published on Nov 11th. NYT’s reporter Ian Austen wrote that FLAP was involved in two legal cases to try and prosecute building owners using legislation to protect migratory birds. A judgment one one of them was reported on Nov 14th in The Record where you can find the complete story.

In brief, the owners of a cluster of high-rise towers, considered the deadliest building complex in the city for bird strikes, were defending themselves against three charges brought under two piece of animal protection legislation  in a test case. The judge dismissed the case but the two-year legal battle ironically achieved one of its main objectives. When hearing began in 2011, the building owners began working with FLAP to try and deal with the problem by retrofitting the towers with ‘an outer-layer film designed to steer birds away’ . They also ‘established “bird action stations” to assist FLAP volunteers in their efforts to collect and tag bird strike victims,’ As a result of the film, FLAP reports that deaths had dropped to 200 or so in 2011. [Incidentally, The Record reports that Mesure’s estimate of bird deaths in Toronto as one million a year – still a lot of birds.]

*

Photo by Carl Vomberg of 206 birds collected at 49 sites in Manhattan (2th April-24th Nov 2002), a fraction of the birds killed in the borough during that period. Source: Window Pain - David Sibley (Birders World Dec 2008)

Find out what is happening in Chicago with the Chicago Bird Collision Monitors who, since 2003 have been working with others to persuade building owners to voluntarily reduce lighting during the spring and fall bird migration seasons.

A detailed account of their activities is carried in an excellent article in Audubon magazine  - ‘Pain In The Glass by Julie Leibach   - which raises some very interesting issues:

• Most people simply aren’t aware of the problem:

‘ Birds that hit buildings at night or during the early morning hours often go unseen, scavenged from the ground by resident predators lurking nearby such as gulls and crows, swept up by sanitation crews, or power-washed out of sight.’

• Sustainable buildings

‘a growing trend toward environmentally responsible building holds promise, as bird advocates, conservationists, and architects tout what they consider a vital sustainable design concept: bird safety—which, in a cruel twist, could be undermined by a building’s other environmental attributes, such as rooftop gardens and energy-efficient windows with reflective coatings. “[Architects and their clients] can use all the recycled material they want, they can save all the energy they want,” says Daniel Klem Jr., an ornithologist who has devoted his career to studying bird collisions. “But if their building is still killing birds, it’s not green to me.”

 

More information at Birds and Buildings  who advise: ‘If your creating “visual noise” on or around a window, be sure that the openings are no larger than a handprint.’

*

A Northern Cardinal and the reflection that killed it. Source: Birds and Windows

One of the world’s experts on this largely unrecognised problem is Prof Daniel Klem Jr, an ornithologist at Muhlenberg College in Pennsylvania, who has been studying the issue for many years. According to a 2004 interview plate glass, reflective or not, is the biggest killer of birds after habitat destruction. Suburban buildings are as much of a problem as skyscrapers. Klem estimates that collisions with glass kill an estimated 98 million to 976 million birds a year in the US alone.

According to his 1990 paper BIRD INJURIES, CAUSE OF DEATH, AND RECUPERATION FROM COLLISIONS WITH WINDOWS this represents  0.5 to 5.0% of the 20 billion birds estimated to compose the continental U.S. bird population after the breeding season each year. By comparison, approximately 3.5 million (2.0%) bird fatalities are due to pollution and poisoning, 57 million (29.2%) result from road collisions and 120.5 million (61.5%) from hunting. He writes: ‘I suspect that additional study will reveal glass panes to exact the highest toll of any human-related avian mortality.’

‘My experimental results have revealed varied and effective methods of preventing bird strikes….Glass panes must be completely covered if collisions are to be eliminated. Covering windows with netting is most effective when cost and aesthetic appearance are acceptable. Alternatively, glass panes must be transformed into obstacles that birds can recognize and avoid… windows must be uniformly covered with objects on or near the glass surface and separated by 5 to 10 cm. I found 2.5 cm cloth strips oriented vertically and separated by 10 cm [to be most effective]….For new or remodelled buildings, architects and designers are encouraged to install windows at an angle such that the pane reflects the ground instead of the surrounding habitat and sky…Single objects such as falcon silhouettes or owl decals, large eye patterns, various other pattern designs, and decoys did not reduce strike rates… they fail to prevent most strikes because they cover only part of the glass and are not applied in sufficient numbers to alert the birds to the glass barrier. Glass surfaces must be uniformly covered with objects or patterns, separated by 5 to 10 cm, to effectively prevent bird strikes at windows.’

See also: Make Your Windows Safer for Birds [Cornell Lab of Ornithology] and The Bird Screen Company

*

Composite photo of birds killed at buildings in Baltimore, by Daniel Lebbin, ABC. This photo come from the site of the American Bird Conservancy.