Mule deer near Denver, Colorado Nature Picture Library/Alamy
For innumerable generations across western North America, cougars and mule deer have been locked in the struggle of predator versus prey. But humanity and its ubiquitous artificial light may now be scrambling this relationship.
The Intermountain West region of the US is sparsely populated, but contains many cities growing at an explosive rate. This means the region’s inky black night skies are becoming increasingly illuminated, and this extends beyond the vicinity of just roads and houses, says Mark Ditmer, a wildlife ecologist at Colorado State University.
Most studies on the impact…
