Home Range and Habitat Use by Wolverines in Southcentral Alaska

Abstract

A wolverine (Gulo gulo) population was studied in the Susitna Basin southcentral Alaska from 1980 to 1983. Based on logarithmic extrapolations, annual home range sizes were estimated at 535 and 105 km2 for males and postpartus females, respectively. Wolverines utilized significantly different (P < 0.05) elevational strata during different seasons (: = 1,043 and 818 m for Apr-Oct and Nov-Mar, respectively), probably in response to differences in prey distribution and abundance. Habitat analyses showed an avoidance forest types in summer and tundra types in winter. J. WILDL. MANAGE. 50(3):460-463 The wolverine, the largest terrestrial mustelid, has a circumboreal distribution and a valuable pelt. Because wolverine population densities are naturally low and the elusive animals occupy remote habitats, few studies have been conducted. This paper describes home range, movements, and habitat use by wolverines in southcentral Alaska. This study was supported by the Alaska Power Authority and the Alaska Dep. Fish and Game (ADFG). Appreciation is expressed to ADFG employees S. R. Peterson and R. J. Tobey for reviewing early drafts the manuscript. E. A. Goodwin provided critical lab time and support. S. M. Miller provided statistical support. K. Z. Adler handled typing and bookkeeping throughout the project. Pilots V. and C. Lofstedt, H. C. McMahan, and A. and J. Lee participated in the field aspects the project. STUDY AREA AND METHODS The study was conducted in a 7,700-km2 portion the upper Susitna River Basin in southcentral Alaska. Characteristics of the habitat have been described previously by Skoog (1968). Elevations range from 260 to 2,200 m. Low elevations are dominated by spruce (Picea spp.) forests, with a shrub and deciduous transition zone blending to tundra and shrub birch (Betula spp.) habitat types at higher elevations. From 1980 to 1983, 22 wolverines were captured, radiocollared (Ballard et al. 1982), and tracked from fixed-wing aircraft. Wolverines were subjectively aged based on tooth wear patterns and degree maturation reproductive organs. Radio transmitters (Telonics, Inc., Mesa, Ariz.) were enclosed in metal canisters, and the transmitter-to-antenna connection was encased in urethane. Collar webbing was made butyl rubber with an internal stainless steel whip antenna. The entire radio-collar package weighed 430 g. Wolverine locations were gathered whenever weather and daylight permitted and were plotted on 1:63,360-scale U.S. Geological Survey topographic maps. The following data were recorded: date, time, activity, association, elevatio , aspect, slope, and associated habitat type (Viereck and Dyrness 1980). Availability habitat to the animals was determined by recording the habitat type at each section corner the mapped study area (McKendrick et al. 1982). Use habitat was determined by plotting all wolverine locations that were within the mapped area (N = 178) and tallying corresponding types. Statistical comparisons between availability and use were determined by a standard F-test. Logarithmic transformations based on the relationships between the number locations and cumulative home range size were used to project annual home range sizes. RESULTS AND DISCUSSION From April 1980 to November 1983, length contact with instrumented wolverines ranged from 1 to 426 days (f = 147). A total 258 point locations was gathered. Mortality (N = 10) and suspected transmitter failure (N = 7) were the primary reasons for loss contact. In 1983, transmitters were redesigned to reduce failure. Home Range The relationship between number locations and home range size was examined (Fig. 1) and used to estimate total annual home range