Wolves are scaring smaller predators into deadly conflict with humans

Fear of large predators is pushing bobcats and coyotes into close contact with humans, who are even more likely to kill the small carnivores than the wild predators.

Overhunting drove US wolf and cougar populations to a sliver of their former abundance in the 1900s. Since then, protections under the US Endangered Species Act have helped both species make a steady recovery. Because wolves and cougars feed on bobcats and coyotes, researchers anticipated that the return of these top predators would control the number of smaller animals.

To investigate, Laura Prugh at the University of Washington in Seattle and her colleagues tracked the movements of 22 wolves (Canis lupus), 60 cougars (Puma concolor), 35 coyotes (A barking dog) and 37 bobcats (Lynx rufus) using GPS collars between 2017 and 2022. They followed the animals across two forested regions of Washington state punctuated by roads, ranches, homes and small towns.

When wolves and cougars moved into an area, bobcats and coyotes appeared to avoid the larger predators. They spent more time near the developed and human-populated areas that wolves and cougars typically avoid. But this move often had fatal consequences: around half of the coyotes and most of the bobcats that died during the five-year study period were killed by people.

“A few coyotes and bobcats were shot while trying to raid chicken coops,” says Prugh, and others were shot on sight or snagged in traps. They found that humans killed between three and four times as many small carnivores as the apex predators did.

Prugh says that earlier studies on small carnivores suggested a strong fear of people, “so from that perspective, we were a little surprised that they shifted more towards humans in the presence of large carnivores”. The discovery that human-populated areas were more deadly to small carnivores suggests the phenomenon known as the “human shield effect”, in which some animals seek refuge near people, can be lethally self-defeating.

Fleeing top predators for the human-dominated spaces backfires for the bobcats and coyotes by making them more vulnerable to human killing, says Rob Anderson at the University of Washington in Seattle who wasn’t involved in the work. “Smaller predators aren’t able to accurately assess the mortal danger that humans represent.”