Every year throughout the United States, hundreds of bird species migrate north to their spring nesting grounds, returning south in fall as the weather turns cold. During the course of their journey migrating birds face many challenges, at least some of them caused by re-shaping of the landscape due to human activities. From depletion of natural wetlands to conversion of forests into farmland, modern society has altered the landscape in many ways since the migration patterns of North American birds first evolved.
However one of the most serious and potentially easily addressed dangers migrating birds face are collisions with brightly lit communications towers. For this reason groups like Defenders of Wildlife are pushing the Federal Communications Commission to adopt guidelines that minimize bird deaths at these buildings.
According to the American Bird Conservancy, up to 50 million birds are killed each year when they collide with communications towers, such as those used to guide aircraft that are coming in for a landing. Many of the casualties belong to tropical species on their way south to spend the winter in Central and South America or the Caribbean. These species may face other pressures in their winter habitat due to degradation of destruction of tropical forests—so preventing other threats to their survival is especially important.
A total of more than 230 bird species have been recorded as being affected by communications towers. Some of the species most frequently found dead due to collisions include the golden-winged warbler, cerulean warbler, seaside sparrow and wood thrush. Most of the collisions occur at night under foggy or overcast conditions, when migrating birds appear to be drawn to the lights from tall communications towers.
Studies on the causes of bird-tower collisions suggest certain types of light may interfere with the visual or magnetic clues migrating birds use to stay on-course, causing them to veer away from their migration path and toward the source of the light. Though the details of what prompts these collisions are not completely clear, some types of tower lighting appear to be far more dangerous to birds than others. According to at least one US Fish and Wildlife Service study, lights that flash on and off with a longer period of time between flashes may be much less likely to attract birds than lights that blink on an off more rapidly. Strobe lights also seem to be less attractive to birds than other types of lighting. By designing communication tower lighting with the needs of migrating birds in mind, these structures can be built with minimal impact on birds and without compromising aircraft safety.
With this goal in mind, conservation organizations like Defenders of Wildlife, the American Bird Conservancy, and the National Audubon Society have recently partnered with a coalition of communication industry groups to draw up recommendations for how migrating birds can be protected. The partnership urges the Federal Communications Commission (FCC), which regulates communications towers, to take new steps to make these structures as bird-friendly as possible. Specific recommendations include outfitting new communications towers with the type of lightly least likely to attract flying birds, and ensuring that existing towers which undergo significant upgrades have their lighting replaced. Partly in response to these efforts, the FCC is now initiating an environmental review of the registration program for new towers.
Though a plan to protect birds from fatal collisions has not been adopted yet, conservation groups remain hopeful the FCC will decide to protect birds in a way that complies with environmental laws, as part of its review process. Defenders of Wildlife is urging its supporters to contact the FCC and show an outpouring of public support for rules that prevent unnecessary bird deaths.