Even far from the city, light can threaten wildlife. To avoid predators, says conservation biologist Paul Beier of Northern Arizona University, "a lot of herbivores just eat much less under moonlit conditions." Artificial glow may make every night seem lit by a full moon, perhaps resulting in chronic underfeeding. Moreover, he says, "lighting can be very disorienting for animals that are trying to move at night." So wildlife corridors might be compromised by even a single lit roadway, says Travis Longcore, coeditor of the book Ecological Consequences of Artificial Night Lighting and codirector of the Los Angeles-based Urban Wildlands Group. "If the corridors aren't dark, the animals they're protected for aren't going to use them."
Glare also endangers sea turtles, bats, and other species, Longcore says. Glowing beacons on communication towers attract and disorient migratory birds, sometimes causing thousands to perish in collisions in a single night. An unpublished study by Joelle Gehring, a scientist with Michigan State University, shows that switching the towers' solid red beacons to flashing ones would slash avian mortality. Gehring is now working with agencies and industry groups to determine if the change is feasible and safe for low-flying aircraft.
Local communities, meanwhile, are taking light-limiting steps of their own. In Illinois, the lieutenant governor has commended the example of Homer Glen near Chicago, which in December became the latest of numerous municipalities nationwide to pass an ordinance requiring new businesses to install fixtures that minimize glare by directing light downward; limit their per-acre light output; and turn off nonsecurity lights soon after closing for the night. Residents like Debra Norvil, who helped craft the rules, also are complying with certain restrictions. Norvil has removed some of her landscape lighting and turns off the rest at 10 p.m. "The night sky is a national treasure," she says.
And while light pollution "isn't our nation's biggest problem," says Moore, "it's one of the easier environmental problems to fix. You can change a light bulb, and it's done."