Light pollution disrupts the navigation, behavior, and survival of billions of migratory birds annually. Understanding the mechanisms and available solutions helps individuals and communities take meaningful action.
Light pollution impacts on migratory birds represent one of the most direct ways that human infrastructure choices translate into wildlife welfare consequences at continental scale. Birds navigating at night use a combination of stellar, magnetic, and geographic cues refined over millions of years of evolution. Artificial light at night disrupts these systems: lights attract birds, disorient their navigation, and cause them to circle buildings until exhausted or until they collide with glass surfaces. Individual birds caught in light traps may circle for hours, burning energy reserves needed for the remaining thousands of kilometers of their migration. Those that survive may continue migration in a depleted state that reduces survival probability. The aggregate welfare significance — billions of birds affected annually — is immense. Critically, effective interventions are available: turning off or reducing building lights during peak migration windows (spring and fall nights) dramatically reduces collisions. Citizen science monitoring programs allow urban residents to contribute data while participating in solutions.