Imagine standing outside in the Central Valley of California on a brisk October evening. A setting crescent moon pricks the silhouetted coastal range to the west as you gaze up into the starry sky. Suddenly you sense an energy, a rush of soft flurrying, in the speckled indigo overhead: birds on the wing, nocturnal migrants--Wilson's warblers, say, flying south from their breeding grounds in Alaska toward northern Mexico, where they will overwinter. Using a sophisticated assortment of biological tools--a sun compass (useful even at night), a star compass, and even a magnetic compass--they orient themselves and navigate southward along the Pacific flyway. Flying in darkness, they avoid predation. During the day, they rest and feed, preparing for the long, demanding night ahead.

In fair weather, as tonight, their path is clear. Many thousands of feet high in the sky, they flap along at a steady rhythm, steering by the stars. The thought of their valiant effort stirs the soul.

Now imagine a stormy March night. The wind is howling and rain lashes at your windows. You cozy up before a crackling woodstove, not giving the idea (much less the reality) of migrating birds a second thought. The birds, though, are out there, heading north to their breeding grounds. Storm clouds have pushed them landward, where there's at least some visibility; the gale blows them about in their course. Flying along in the miserable wet, they spy a light, and another, and some more--beacons that may promise release from the dark and cold. They home toward the brightly lit skyscrapers.

Deadly Lights
These beacons, however, promise not safety, but the opposite. Confused by interior and exterior building lights and unable to see the glass, thousands of birds collide and are injured or killed each night in our large cities, particularly during the spring and fall migrations. "The worst I've experienced," said Michael Mesure, founder of the Toronto-based nonprofit FLAP (Fatal Light Awareness Program), "is, we picked up over 500 birds over a six-hour period at two structures [in downtown Toronto]. We just stood there and would catch the birds as they fell. It was that bad." The annual toll in North America extends into the millions--just how many is impossible to say, but experts suggest from 50 million on up.

People have grown to appreciate that these fragile creatures are threatened by habitat loss, pollution and pesticide use, overhunting, and even feral cats, but the problem of collisions is not widely recognized. And it's not just buildings that get in the way: communication towers, wind turbines, bridges, lighthouses, oil platforms, cooling towers, and emission stacks take their toll as well. Even if the birds don't collide (at whatever time of day), the inevitable lights associated with these structures at night--ensuring pilot safety--can lure them out of the dark into the pool of visibility, where, essentially trapped by the light, they flap around until finally they drop to the ground, exhausted and vulnerable to predation. The same happens with spotlights directed skyward, such as the tribute beams at New York's Twin Towers site, and with ceilometers, light beams used at airports to gauge the height of the cloud ceiling.

Brad Keitt, a research biologist with Island Conservation, did his graduate research in the islands off Baja California, where there are huge colonies of seabirds. "On this one island," he said, "there was a lighthouse with a broken window. You'd go up there and there'd be piles of birds. Some were alive; they'd just gotten in there recently. And others were dead, had been in there for a long time. They are attracted to light, and they'd fly up and either hit the window or go through the broken window and end up inside."