Wolverine Population Assessment in Glacier National Park: Comprehensive Summary Update

Copeland, Jeffrey; Yates, Richard

The Glacier National Park Wolverine Research Project completed its fifth and final year of study. Research pursued two primary objectives: 1) live-trap, radio-instrument and monitor wolverine to describe their distribution and reproductive status, and 2) locate natal and maternal dens, and rendezvous sites, and characterize associated landscape features. Secondary objectives included the investigation of wolverine demographics, the relationship between reproduction and winter recreation, and a description of wolverine home ranges, movement, and habitat use. Twenty-eight wolverines (13 males, 15 females) were captured and 27 instrumented, providing over 30,000 relocations. We documented 23 reproductive sites for 6 adult females. Dens occurred beneath deep snow most commonly on upper slopes of sparse timber structurally tied to downed woody debris, rock caves, and boulder talus. Seven kits were captured and instrumented at den sites. Monitoring of kits and mothers through their first summer provided 30 maternal care (rendezvous) sites occurring primarily in boulder talus and cliff areas. Kits became independent of their mother by mid to late September, at 6-7 months-of-age. Kit survival to adulthood was low as evidenced by 5 of 7 kits dying during their first year. In cases where the cause of death could be determined, mortality was attributed to predation (1), shooting (1), and fall from a cliff (1). Two adults died during the study period; one female killed in an avalanche, and one male from predation. Three subadults were killed during the study: a male was legally trapped and killed outside GNP as a disperser, a second subadult male was killed by construction activity on the Going-to-the-Sun Road in GNP, and a subadult female appeared to have been gored to death, presumably by a mountain goat. GPS collars provided data on rates of movement, habitat use, activity, and social interactions. Wolverines followed traditional routes moving over 150 km/week at a rate of approximately 4 km/hr with long-distance movements (commonly exceeding 10 km) interspersed with localization periods at foraging and/or resting sites of up to 60 hrs. Travel routes commonly intercepted uninhabited dwellings and developed areas within the park, and included snowbound roads and trails. Two young wolverines dispersed from GNP during the study period. One subadult male traveled approximately 100 miles to the Northwest Peaks Natural Area in northwestern Montana in 2004. A subadult female moved 55 miles south into the Swan Range in early 2007. Wolverine home ranges averaged 521 km2 for males and 139 km2 for females. Scat (n=142) and prey remain (n=55) samples are being analyzed to provide food habits data. DNA profiling indicates limited population structuring with a few established resident males contributing to most of the reproduction. Based on habitat distribution and spatial use, GNP appears to support a stable-to-increasing population of between 40 and 45 individuals.

Wolverine Population Assessment in Glacier National Park: Comprehensive Summary Update

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