Effects of Mid-winter Snow Depth on Stand Selection by Wolverines, Gulo gulo luscus, in the Boreal Forest

Abstract

Wolverines (Gulo gulo luscus) in a study area in the boreal upland forests of northwestern Alberta and northeastern British Columbia (approximately 57°N) were noted to be limited to upland landscapes, despite abundant food in adjacent lowland landscapes. Snow-tracking suggested that the species was selecting for the densest climax conifer stands for travel in search of food. It was hypothesized that snow depth was a limiting factor for Wolverines in the boreal forest during midwinter, and that they selected for this stand-type because of the buffering effect of this type of canopy on ground snow-depths. A series of snow-depth measurements were collected. Snow depths collected along Wolverine trails were very significantly lower than random snow depths collected under upland canopy (F = 32.84, df = 1, P << 0.010). There was a significant buffering effect on snow depth indicated for upland canopy (F = 11.1, df = 1, P < 0.010), while adjacent lowland canopy had no significant buffering effect on snow depth (F = 3.45, df = 1, P > 0.05). Wolverines were hypothesized to be limited to upland landscapes in the study area because of the buffering effect on snow-depth of the stand types found there, and not for reasons of food availability. Climax conifer stands were interpreted as being of high importance to Wolverine survival during winter. Conservation implications include the detrimental effect on Wolverine populations likely to result from current timber harvesting practices in the boreal forest.