# Fall bird migration and light pollution risks > Live situation record from CLSTR: https://clstr.news/situations/fall-bird-migration-and-light-pollution-risks > Updated: 2026-09-16T18:45:43.000Z. Sources: 6. Developments: 2. During the fall migration season, conservationists and wildlife agencies have issued warnings regarding the impact of artificial light on nocturnal migratory birds. Because approximately 80% of these birds travel at night using celestial cues, light pollution can cause disorientation and fatal collisions with buildings. Data from the BirdCast project, which uses weather surveillance radar, has tracked massive migration surges across the United States. In Wisconsin, specific peak periods were recorded in September, with an estimated 98 million birds passing over the state on September 9 and 84 million on September 12. To mitigate mortality, experts recommend turning off unnecessary outdoor lights between 11 p.m. and 6 a.m. BirdCast also issues ‘Lights Out Alerts’ during the top 10% of migration nights to notify the public of high bird traffic. Other suggested protective measures include using window decals and keeping cats indoors. ## Timeline ### 2026-09-16: Wisconsin experiences massive bird migration waves Millions of birds are migrating over Wisconsin this September. Experts recommend turning off outdoor lights at night to prevent disorienting songbirds and reducing fatal window collisions. 2 sources. https://clstr.news/cluster/wisconsin-experiences-massive-bird-migration-waves ### 2026-08-24: Migrating birds face disorientation from artificial lights during fall migration Conservationists urge people to turn off outdoor lights during fall migration to prevent disorienting nocturnal birds and reduce fatal building collisions during massive migratory surges. 4 sources. https://clstr.news/cluster/migrating-birds-face-disorientation-from-artificial-lights-during-fall-migration --- Cite as: Fall bird migration and light pollution risks. CLSTR, https://clstr.news/situations/fall-bird-migration-and-light-pollution-risks