Apparent predation of a bison (Bison bison) calf by a Grizzly Bear (Ursus arctos) in southwestern Yukon

Abstract

Grizzly Bear (Ursus arctos) predation on American Bison (Bison bison)—particularly calves—was likely once common.
However, with the range-wide collapse of bison near the close of the 19th century, the two species no longer co-occur across much of their current distributions. Over the past 60 years, efforts to reintroduce bison to their native range have resulted in a few small areas where the two species once again co-occur. Yet, predation of bison by bears is apparently rare and has not been observed outside Yellowstone National Park, where both species have existed for millennia. On 28 June 2023, we observed an adult male Grizzly Bear protecting a buried bison calf that it had apparently killed in Yukon, Canada. This is the first observation of apparent predation of a bison by a Grizzly Bear outside Yellowstone National Park. Our observation further highlights how reintroduced bison are becoming integrated into local food webs, which is a key indicator of ecological restoration.