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."

Just why seabirds are drawn to light is poorly understood, but one theory is that they have a hard-wired attraction to the lighter color of the ocean, which allows them to leave the land and go to sea to feed. Travis Longcore of Urban Wildlands, a nonprofit based in Los Angeles, suggests another possibility: when fish swim through bioluminescent plankton near the ocean's surface, the moving swash of light may signal the presence of prey. Keitt told another story, of a fishing boat in Alaska: attracted to the boat's lights, so many birds were landing on the vessel that the crew feared that they would actually sink it. The captain ended up turning off the lights and shoveling the birds overboard. In the darkness, the onslaught ceased.

In fact, turning off the lights, though in that case an act of desperation, has been found to be an immediate and effective solution to the problem of bird strikes. FLAP's Mesure told of a power generation station on Lake Ontario with two floodlit emission stacks 15 to 20 stories high. "There was a noted history of bird strikes occurring at these stacks. Then in a single weekend, over a two-day period, some 10,000 birds were salvaged from around this structure." After a study concluded that the illumination was to blame, strobe lights for pilot navigation were substituted for the spotlights, "and the problem pretty much disappeared," Mesure said. "You will find no other environmental issue out there that is so easily resolved. How often can you say that you flick a switch, and it disappears, it stops? It's a win-win situation--everyone benefits: you save money, you save energy, you reduce pollution, you see the night sky, and you reduce bird collisions."

A recent study of communication towers in Michigan showed that tall towers (greater than 500 feet or so) and guyed structures were significantly more likely to kill birds than medium towers and self-supporting structures. An equally important factor in avian deaths, however, was lighting. And the findings supported the Lake Ontario conclusions: flashing lights lead to considerably less avian mortality than steady-burning lights.

Longcore said that it's not known why steady-burning lights have this effect. "It could be this sort of overwhelming not wanting to leave and go into the darkness, once they're in the cone of influence. You can imagine if you're around a campfire at night: that's a powerful thing that prohibits you from adjusting to going out into the darkness. If you steel yourself and walk away and close your eyes and adjust a little bit, then all of a sudden you can see. But when you're right around it, it's like this overpowering visual stimulus."

Currently, Federal Aviation Administration (FAA) guidelines specify that a tower must have flashing lights. White strobes can be used alone, but these tend to be obnoxious to nearby residents. Red flashing lights are the alternative; the catch is, they must be paired with steady-burning red lights. Joelle Gehring, conservation scientist with the Michigan Natural Features Inventory, explained that when the guidelines were established some four decades ago, the white strobe lights were found to act "like a camera flash to a pilot's eye; it gives some sort of depth perception. The red flashing lights were not as present to the pilot's eye, so they needed steady-burning lights as well."

When the FAA gave permission for some of the Michigan tower lights to be manipulated, the results were definitive: steady-burning lights, even if flashing lights are present, increase the number of birds killed. Encouragingly, the FAA has recently committed to conducting conspicuity studies with an eye to changing the guidelines. "With modern technology for pilots," said Gehring, "can we indeed turn off those steady-burning red lights and still have pilot safety? They're pretty optimistic about either turning them off or making them only flash, and they can do both those things from the ground," without the need for expensive retrofitting. "That would reduce avian collisions by as much as 70 percent. It's not obnoxious to the neighbors, it's essentially free, and it would save electricity and maintenance costs as well."

Again: it's a win-win situation--but one that will depend on voluntary efforts, since the FAA, assuming it approves the changes (which could happen as soon as 2010), will only allow them to be made; it will not mandate the changes. It will be up to individuals and organizations near the many communication towers sprinkled across the United States to ask tower operators to switch, and to make the case for why they should. (California alone, as of 2004, had 652 communication towers, 12 of them over 800 feet tall.)

Lights Out
Around the country in our largest cities, skyscrapers glow brightly through the night. Suburban streetlights glare through bedroom windows. Unshielded outdoor lighting floods the sky, which in some places no longer reveals a twinkling firmament of stars but only a sort of extended twilight.

According to Bob Gent of the International Dark-Sky Association, a nonprofit organization that was started to benefit astronomers but has extended its efforts into the natural world, 30 percent of outdoor lighting (plus some indoor lighting) is wasted, at a cost of $10.4 billion and 38 million tons of carbon a year in the United States alone. The good news is, the situation is fairly easy to remedy. We don't have to turn everything off, said Gent. It's about using the right amount of light, and only when and where it's needed.

Saving energy is a valuable goal in its own right, but the plight of migratory birds has caught the imagination of concerned citizens as well, leading to a two-pronged argument for a reduction in artificial lighting. In 2005, the City of Toronto (in partnership with FLAP, among other groups) launched "Lights Out Toronto!," a public awareness campaign aimed specifically at encouraging individuals, businesses, property owners, and building managers to help reduce avian mortality. Since then, Chicago, New York City, Detroit, and Minneapolis have followed suit. In 2007, an estimated 2.2 million residents of Sydney, Australia, switched off their lights during "Earth Hour," briefly reducing that city's energy use by more than 10 percent. And on March 29, 2008, more than two dozen cities worldwide dimmed their lights in an hour-long demonstration of energy- and bird-saving solidarity organized by the World Wildlife Fund.

Currently, San Francisco is gearing up for its own Lights Out program, due to begin in mid-February and to continue year-round, rather than being restricted to the spring and fall migration periods. Targeting the 50 tallest buildings (34 of which are more than 400 feet high, including the 853-foot TransAmerica Pyramid), the City's Department of the Environment and the Golden Gate chapter of the Audubon Society, in conjunction with the American Bird Conservancy, are spearheading the effort, which will encourage installation of occupancy sensors where possible, or manual lights-out or nighttime curtain-drawing efforts. Pacific Gas & Electric, which is working with many downtown office tower owners and managers to conserve energy, is on board as well, and will offer both education and incentives.

This summer, volunteers have been pounding the sidewalks below San Francisco's skyscrapers, gathering statistics on bird mortality. "It's difficult," commented the Audubon Society's Noreen Weeden. "Most of our volunteers want to go out and see live birds. Here, people have to get up really early and walk around downtown and survey before 6 a.m., because at that time building maintenance people are out with power washers and spraying everything down, and after 6 you can't really tell." Despite this logistical difficulty, the results are conclusive--adding a little more fuel to the argument the City will start bringing this November to building owners and managers, to convince them to make a change come February.

"One of the biggest challenges," said Mesure, "is that the vast majority of people don't understand the diverse world of birds. To the average individual, a bird is a bird is a bird. If the only bird they recognize is an American robin, then every bird is an American robin." Not only that, but in an urban environment, most people encounter very little wildlife--and the most common sort of wildlife they do encounter is birds. "So in the back of people's minds," Mesure continued, "birds are holding their own. But that poor panda bear in some other part of the world that we don't see but that we hear so many horrible things about, and it's cute and cuddly, they'll gravitate toward helping to support that sort of issue. So it's about education on issues that we have right here on our doorstep."

Weeden said that the bird carcasses being collected now from San Francisco streets will be donated to the University of California Berkeley Museum of Vertebrate Zoology, which will compile a geospatial species map. The birds will also be used for educational purposes. "It's the best possible outcome, given their sacrifice," she commented. Gehring echoed this view. "I'm a scientist, and so I'm taught to not care about the individual carcass on the ground. But of course, every time I see a carcass, it bothers me. It's part of my soul. And so it's so nice to potentially see a resolution to this issue. These birds didn't die in vain, like they've been doing for decades. Hopefully we can learn something from their death and make a difference with it."