Light pollution entrapping migrating birds in cities, leading to their death en masse: Study

Weather radar data used to map bird stopover density

Scientists used weather radar data to map bird stopover density and found that birds were landing more in the area which was illuminated with artificial lights. 

The study pairs more than 10 million radar observations with landscape and other place-based information to try to explain why birds choose to rest where they do. Out of 49 predictors, light pollution was the No. 2 predictor of stopover density.

City lights—an ecological trap

City lights lure birds into what can be an ecological trap, said lead author Kyle Horton, an assistant professor in Colorado State University’s Department of Fish, Wildlife and Conservation Biology.

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Buildings that lead to collisions, less habitat, scarcer food, and more people and cats can make cities less-than-ideal rest stops for migrating birds, the study found.

Possible solutions

Scientists are divided regarding what should be the best way to tackle this menace—implement massive changes in urban centres to make them more hospitable or simply take steps to not let birds enter cities in the first place by running targeted light-out campaigns?

Some say a fine balance should be struck.

“We don’t often think about light as a pollutant, but it checks all the boxes of what pollution is,” Horton said.

Light pollution doesn’t negatively impact birds only but also humans.

It can disrupt humans’ circadian rhythms, leading to health problems, including depression, insomnia, cardiovascular disease and cancer. For now, we have a simple solution to this crisis, observes Horton.

“If we turned off all lights tonight, there would be no birds colliding because of lights tonight,” Horton said. “The impact is immediate and positive for birds.”