Birds

The effect of artificial lights on birds has been known for centuries. In the past, people used flame and lights to attract birds at night to capture them for food. Since their inception, there have been reports of seabirds attracted to the light beam of lighthouses. Artificial lights can "trap" migratory birds by bleaching their visual pigments, causing them to lose sight of the horizon and circle within the cone of light endlessly. They then can die from exhaustion or collision with the light source. It can extend the day for diurnal species of songbirds, making them more susceptible to predators as they sing out their location, or causing them to breed too early since they associate breeding with longer days. It can attract seabirds away from their normal feeding grounds, possibly because these birds feed on bioluminescent sea animals and are cued in to low levels of light.