West Goshen Township is asking residents to turn off unnecessary outdoor lights during the fall migration season to protect millions of birds that fly over Chester County at night.
The township posted the notice on its website on Wednesday, Sept. 16. It cited the National Audubon Society's Lights Out program, which has encouraged communities to reduce nighttime lighting during migration seasons since 1999.
Most migratory birds travel after dark, lifting off 30 to 45 minutes after sunset, with the greatest numbers airborne two to three hours later. The birds navigate by stars and other environmental cues. Artificial light can pull them off course and into developed areas, where they collide with buildings and other structures, the township said.
Millions of birds pass through Chester County during fall migration. According to BirdCast, a migration forecasting project from the Cornell Lab of Ornithology, the county's peak fall migration runs roughly from Wednesday, Sept. 23 through Oct. 27, based on radar data collected from 1995 to 2018. At least 80 percent of migratory bird species fly at night.
The toll is steep. A 2024 study published in PLOS ONE found that building collisions kill well over 1 billion birds annually in the United States, revising earlier estimates sharply upward. Only 40 percent of collision-injured birds survive even with professional rehabilitation, according to the American Bird Conservancy.
"If we don't address artificial light and glass, we'll continue to lose over a billion birds in the US annually," Dustin Partridge, director of conservation and science at NYC Bird Alliance and a co-author of the study, said in August 2024, when the research was published.
The township's notice lists five steps residents can take:
- Turn off unnecessary outdoor lights.
- Close blinds or curtains in brightly lit rooms.
- Use motion sensors so lights run only when needed.
- Aim outdoor lighting downward.
- Where lighting is necessary, choose lower-wattage, warmer, amber-colored bulbs.
The request applies across the fall migration season, though the township did not specify an end date. BirdCast data suggests peak activity in Chester County tapers off by late October.
Locally, the Valley Forge Audubon Society is promoting Lights Out Philly, a voluntary program that asks property owners to block or turn off external and internal building lights at night during migration. Residents in West Chester and East Goshen can follow the same steps.
Upcoming
The John James Audubon Center at Mill Grove and Valley Forge Audubon Society are hosting a beginners birding tour in September. Chester County's peak migration window opens Wednesday, Sept. 23.
