A Simple Human Action Leads Confused Birds Astray
For birds and other species, too-bright nights are a matter of light and death - but there's an easy way for humans to help, say ecologists.
Off the coast of Australia, birds like the short-tailed shearwaters migrate at night, following patterns from the dusk, moon and stars. They're also attracted to artificial light, says a group of Spanish and Australian ecologists. Birds traveling at sea for the first time are most likely to be confused by streetlights, and can end up stranded after following the wrong glow.
Over a 15 year period, the scientists tracked 8,871 young birds near an Australian island. Close to 40 percent of the fledglings they encountered were dead or dying, grounded and then struck by cars - most frequently on cloudy nights, when the only source of illumination was human-made But there's a simple enough solution: turn off the lights, the scientists report Wednesday in the journal PLOS ONE. "Turning the road lights off decreased the number of grounded birds," the researchers say.
Light pollution has far-ranging effects, as diverse as throwing lemur sex cycles out of whack to impairing rainforest recovery. In a March 2014 study, Costa Rican fruit bats - key rainforest pollinators who can defecate a "seed rain" - were more likely to avoid parts of an enclosure lit by a street lamp, even if there was fruit available.
"The impact of light pollution could be reduced by changes in lighting design and by setting up dark refuges connected by dark corridors for light-sensitive species like bats," bat expert and study author Daniel Lewanzik told the BBC.