Migrating birds are dying flying into buildings at night, attracted and confused by the light. In Toronto, home base of FLAP, the Fatal Light Awareness Program, up to 500 dead birds a day, casualties of the previous night, are collected by volunteers. FLAP describes what happens:
Birds migrating at night are strongly attracted to, or at least trapped by, sources of artificial light, particularly during periods of inclement weather. Approaching the lights of lighthouses, floodlit obstacles, ceilometers (light beams generally used at airports to determine the altitude of cloud cover), communication towers, or lighted tall buildings, they become vulnerable to collisions with the structures themselves. If collision is avoided, birds are still at risk of death or injury. Once inside a beam of light, birds are reluctant to fly out of the lighted area into the dark, and often continue to flap around in the beam of light until they drop to the ground with exhaustion. A secondary threat resulting from their aggregation at lighted structures is their increased vulnerability to predation. The difficulty of finding food once trapped in an urban environment may present an additional threat.
The solution: turn out the lights - or as many of them as possible. This might seem appealing in an era of energy conservation but apparently not so. FLAP's attempts to enlist the support of companies with big buildings has had limited success. In support of the programme, Toronto Hydro has issued a Bird Safety Migration Alert and the city of Toronto is considering modifications to its building design code.
Ironically, a prime example was the light towers at the 2004 September 11 memorial. Intended to honour those who had died flying into the buildings, the memorial light towers lured many birds to their death.