Are city lights killing birds in flight?
The short (and easy) answer is, “Yes.”
The Audubon Society tells us that, while lights can throw birds off their migration paths, bird fatalities are more directly caused by the amount of energy the birds waste flying around and calling out in confusion. The exhaustion can then leave them vulnerable to other urban threats.
“Science” magazine has a stunning statistic. Since 1970, there are three billion fewer birds in the skies above North America.
- In one 2017 week, four hundred warblers, grosbeaks and sparrows were caught in the floodlights of a 32-story Texas skyscraper. They died from window collisions.
- From 2000 to 2020, almost 12,000 sparrows, warblers, thrushes and other birds died at Chicago’s McCormack Place.
- Volunteers estimate that between 100,000 and 200,000 birds perish in Dallas, Texas each year.
The magazine adds that bird flocks “face death by a thousand cuts.” adds “Science. Light pollution, climate change, vanishing habitat and pesticides all take their toll
Ornithologists fear our abundant bird population will become extinct.
Night sky lighting events, like New York City’s “Tribute in Light” installation can attract and confuse thousands of migrating birds. “On each anniversary of 9/11, bird conservationists wait below, counting and listening to disoriented chirps. If the observers report too many birds circling aimlessly in the beams, organizers flip off the lights.”
Using, yes, weather radar, a group led by Cornell University researchers found that within 20 minutes of lighting up, up to 16,000 birds crammed themselves into a half-kilometer radius. Turning off lights dissipated the cloud of birds.
What can cities do?
The Science article offers these suggestions:
- Participate in Audubon Society’s Lights Out program.
- Check BirdCast, bird nocturnal migration forecast maps from Colorado State University and the Cornell Lab of Ornithology.
- Pass legislation to dim or turn off most nonessential lights by 11 p.m. all year long.
- Require buildings to use bird-safe glass or have dimmer and downcast lights to reduce collision.
- Ban nonessential lighting during migration season for buildings near ecological preserves.
Even halving the number of lit windows in a building can halve the number of bird strikes.
Photo by Andre Benz on Unsplash