Distribution and occupancy of wolverines on tundra, northwestern Alaska

Abstract

Understanding wildlife distribution and habitat use is needed for effectively balancing resource development, wildlife conservation, and Alaska Native subsistence on the North Slope of Alaska, USA. This region includes the National Petroleum Reserve‐Alaska (NPR‐A), a 96,000‐km2 remote area of largely undeveloped lands that is important for wildlife, including caribou (Rangifer tarandus), wolves (Canis lupus), and wolverines (Gulo gulo). We focused our study on spring distribution and occupancy of wolverines in the NPR‐A because a baseline distribution estimate is required to understand current distribution and track changes over time. We conducted aerial surveys of wolverine tracks in snow during March and April of 2014 and 2015, surveying over 84,400 km2 using 100‐km2 hexagonal sampling units. We used hierarchical Bayesian occupancy modeling to determine wolverine distribution and estimate probability of occupancy within each hexagon, relative to measured covariates with potential to affect either detection or occupancy. Probability of wolverine occupancy increased as well‐drained soils increased, suggesting that wolverines prefer drier areas or habitat features associated with well‐drained soils. In addition, as standard deviation of elevation increased, wolverine occupancy also increased, indicating that wolverines may prefer areas with more rugged and variable terrain. Mean elevation was not retained as a covariate in the best‐fitting model, supporting the importance of terrain ruggedness rather than elevation on wolverine distribution within the NPR‐A. Spatially, areas of highest wolverine occupancy occurred within the southern and northeastern portions of the study area, with lowest occupancy in the northern portion of the study area west of Teshekpuk Lake. Based on the spatial pattern of wolverine probability of occupancy, we proposed 4 potential wolverine management zones with varying priorities for monitoring and managing wolverine populations. © 2018 The Wildlife Society.

Spatiotemporally variable snow properties drive habitat use of an Arctic mesopredator

“…We extend this finding to Arctic tundra, likely due to the use of frozen streams and rivers as travel corridors and/or habitat for prey species such as snowshoe hare and ptarmigan. Previous studies have also found that wolverines prefer more rugged terrain in montane regions (Krebs et al 2007), as well as in tundra regions at the occupancy level of selection (Poley et al 2018). Our study extends this finding to habitat selection operating at the within home-range level on tundra.…”

“…Wolverines occur across the study area, although their occupancy is non-uniform and correlates with rugged terrain and the presence of well-drained soils (Poley et al 2018). Generally, wolverines are considered a snow-associated species, and on the Arctic tundra, which comprises a considerable portion of the wolverine's global distribution, the relative importance of snow as a structural habitat component may be higher than in other ecosystems.…”

“…Generally, wolverines are considered a snow-associated species, and on the Arctic tundra, which comprises a considerable portion of the wolverine's global distribution, the relative importance of snow as a structural habitat component may be higher than in other ecosystems. Non-snow structures that are associated with reproductive dens and resting sites elsewhere, such as trees, boulders, and beaver lodges (May et al 2012;Jokinen et al 2019), are sparse or absent on tundra, and although studies of wolverine habitat associations on tundra are limited (but see Magoun 1985;Poley et al 2018), all reproductive dens documented on the tundra have been in deep, drifted snow (Magoun and Copeland 1998), and non-reproductive wolverines have been documented excavating cavities in snow to avoid predators, behaviorally thermoregulate, and cache food (Magoun 1985, Glass et al In press). With few exceptions (e.g., Magoun and Copeland 1998;Pozzanghera et al 2016;Magoun et al 2017), only snow presence/absence data at >500 m pixel resolution have been used to inform the relationship between wolverines and snow, although the ways in which this and other species (e.g., ringed seals, Stirling and Smith 2004) are affected by snow are almost certainly mediated by more complicated dynamically evolving snow properties at much finer spatial resolutions (Magoun et al 2017).…”

“…SSMT end , variable representing whether or not any snow had melted during the preceding 24 h. In addition to snow covariates, we investigated terrain ruggedness, distance to streams/rivers, and distance to lake edges (Table 1, Fig. 1), because these are commonly related to wolverine habitat selection elsewhere (Poley et al 2018;Scrafford et al 2018), or because we expected them to be influential based on our field observations. We decided against including distance to roads as a covariate, since the Dalton Highway is the only road in the study area (Fig.…”

Spatial Patterns of Mercury Accumulation in Wolverine (Gulo gulo) Across the Western Canadian Arctic: Landscape, Climate and Dietary Factors

“…It has been documented that wolverine forages at a variety of elevations in Canada (Lofroth et al, 2007;Slough, 2007). Higher elevation in areas with late spring snowpack (Copeland et al, 2010), and higher topographic ruggedness in alpine and subalpine habitats (Poley et al, 2018) have been associated with wolverine habitat selection.…”