Extremely high migration is expected over Wisconsin Thursday, May 14.
People are encouraged to turn off non-essential outdoor lights from 11 p.m. to 6 a.m. tonight, and ideally, throughout the bird migration season ending in mid-June.
Eighty percent of migrating birds fly at night. Roughly 37 million birds flew over Wisconsin Monday night, according to Birdcast.
"Certain nights bring massive surges of birds moving north, and Wisconsin sits directly in the path of some of the continent’s busiest spring migration corridors,” says Kyle Horton, the Purdue University associate professor who along with Cornell Lab of Ornithology colleagues uses weather radar to generate bird migration forecasts and alerts people when birds are most at risk.
“Turning off unnecessary lights at night is one simple step we can take to help migratory birds pass safely through our skies."
Artificial light can lure them off their migration paths into urban areas where they face more hazards, including windows.
Lights Out Wisconsin formed in fall 2025 to reduce light pollution when dark skies matter most for wildlife and people.
Peak bird migration in Wisconsin historically begins the first or second week in May and lasts about two weeks.
