Migrating songbirds face an obstacle course of human infrastructure — communications towers, wind turbines, lit windows, and light pollution — with billions of deaths annually.
Migrating songbird welfare is threatened by the cumulative effect of human infrastructure hazards. Communication towers with blinking red lights are especially hazardous — steady white or green lights are less attractive to birds. Wind turbines kill raptors and bats that don't detect the slow-moving blades. Lit buildings in cities disorient migrants who use stars for navigation. Individual birds that fall from exhaustion into urban areas may be trampled or killed by traffic. The welfare impact of these deaths involves both the acute trauma of collision and the prolonged suffering of birds that become disoriented and cannot continue migration. Lights Out programs in major cities have produced measurable reductions in collision mortality.