We keep learning how artificial light impacts wildlife.
While many species can be affected, migratory birds are particularly sensitive to lights left on at night.
Migratory Bird Calls
A recent study looked at the impact of light pollution at night and how this affected the calls of migratory birds. The study took place in the U.K. and looked at thrushes. They found that in the brightest urban areas, call rates at night were up to five times higher in comparison to darker villages. The results show that even without high-rise buildings in modest urban areas, bird migration can be impacted, and nighttime lighting should be managed.
Wondering what an increase in call rates means? A University of Michigan study found birds that produce calls during overnight migration end up colliding with lit-up buildings much more frequently in comparison to closely related species that do not make calls. The study says birds that are disoriented by nighttime artificial light produce flight calls that may attract other nearby birds. This creates a cycle of increased death rates as disoriented birds guide other migrating birds to the artificial light.