Migration seasons, spring and fall, are among the most deadly times of year for songbirds. Many of these birds fly thousands of miles through territory they've never been in before, guided only by their instincts and the earth's magnetism. They face the hazards of predators and finding sufficient food to keep them going and finding shelter from harsh weather. For many if not most, however, the most serious hazards they will face will be barriers erected by humans. Although the structures were not intended as barriers, to a migrating bird, flying mostly at night, that is exactly what the huge glass skyscrapers that are a feature of so many cities are.
It is estimated that 90,000 migrating birds are killed each year by flying into buildings in New York City alone. Nobody knows for sure, of course, and the total could be much higher. The nation-wide death toll is projected at about a billion birds, but, again, that estimate may be on the low side. What is known for sure is that this represents a true avian holocaust.
Conservationists, concerned architects and city officials are trying to find solutions that will at least ameliorate the problem. Around the country, several cities' Planning Commissions, such as San Francisco, are adopting bird-friendly ordinances in their rules for new buildings and remodeling projects. In Washington, legislation is pending that would make federal buildings incorporate bird-friendly designs. In addition, some manufacturers are exploring glass designs that use ultraviolet signals visible only to birds. Such initiatives are still in their infancy but do hold some promise for the future. For the present, though, opaque or translucent films, decals, dot patterns, shades, mesh screens — even nets — are the main options available to architects, designers, and home owners, and, admittedly, these are not very attractive alternatives. Perhaps they are more attractive than a yard full of dead birds, though.
What makes the problem even worse is the lights that are often left on through the night in these glass buildings. They disorient the birds and lead them straight into the sides of the buildings with deadly results. Many buildings in New York now participate in a project called Lights Out New York which simply means they turn their lights off at night. Other big cities like Toronto, Boston, and Chicago have similar lights out programs and these are proving effective.
The National Audubon Society and other bird conservation groups are making this a priority in their advocacy for birds, and it is gratifying to see that cities are responding positively. It is believed by most ornithologists that birds' deaths from crashing into buildings are second only to habitat loss as a threat to the survival of birds as a species. It is noteworthy that both hazards - destruction of habitat through development and glass buildings as barriers - are human-made. The greatest threat to avian survival is humans.