Light pollution is changing the way pumas hunt deer in the western United States

By Jake Buehler

Mule deer near Denver Newspaper, Colorado

Naturbildbibliothek / Alamy

For countless generations in western North America, pumas and mule deer have been involved in the battle between predator and prey. But humanity and its ubiquitous artificial light could mess that relationship right now.

The Intermountain West region of the United States is sparsely populated, but it contains many cities that are growing explosively. This means the region’s deep black night sky is increasingly lit, beyond the proximity of streets and houses, says Mark Ditmer, wildlife ecologist at Colorado State University.

Most studies on the effects …