Light Pollution, Birds and Window Collisions
-Mary Coolidge, BirdSafe Campaign Coordinator
Many birds migrate at night, using constellations, the moon, and the magnetic pull of the earth to navigate. Sky glow over lit areas confuses nighttime migrants and lures them into the maze of urban areas, where they may be entrapped by light and circle until they collapse from exhaustion. Migration is already an energetically demanding and dangerous feat, and detours on these arduous journeys can gravely impair birds’ ability to reach their destinations.
The night is actually habitat. Biological systems evolved on this planet in a cycle of dark nights and bright days. Fully 30% of vertebrates and 60% of invertebrates are nocturnal! When we light the night, we fragment the dark and impact ecosystems that rely on carefully timed circadian rhythms that govern cycles of sleep, foraging, mating, migration, flowering, hunting, hibernating, bud burst, leaf drop, and the list goes on. Artificial light at night also disrupts predator prey relationships to the benefit of some and peril of others. It attracts some species and repels others, causes some to sing a night and others to remain silent. When we alter these rhythms, we disrupt carefully choreographed and complex relationships.
The proliferation of urban areas along bird migration routes can present significant threats to migrants both during the day and at night. During the day, window glass presents yet another deceptive and deadly hazard. Window collisions are one of the most critical threats to wild bird populations, killing up to 1 billion birds annually in the US alone. Birds simply do not perceive unmarked glass as a barrier, and fly into reflections of sky and vegetation in window glass.
LightsOut programs help prevent migrating birds from being attracted into developed areas. In addition to reducing collision hazard for migrants, LightsOut programs provide many other benefits, including saving energy and money, reducing our carbon footprint, and preserving our view of the stars!
Today, there is a rapid LED conversion happening around the globe because they offer significant energy savings and reduced maintenance costs. However, early generation LEDs emit blue-rich white light, which scatters more readily in the atmosphere than longer wavelength light, thus contributing to skyglow.
Responsive lighting design meets a range of climate resiliency and sustainability objectives including energy efficiency, cost savings, ecological health, human health, and preservation of the night sky. Window collisions and light pollution are hazards with real solutions It will be the cumulative actions of all of us that will ultimately make the difference.
For more information on how you can help, visit: HERE.
or contact Mary Coolidge, BirdSafe Campaign Coordinator HERE.