DOI: 10.5061/dryad.dr7sqv9vm
title: Data from: Steep and deep: Terrain and climate factors explain brown bear (Ursus arctos) alpine den site selection to guide heli-skiing management

description: Winter recreation and tourism continue to expand worldwide, and where
 these activities overlap with valuable wildlife habitat, there is greater
 potential for conservation concerns. Wildlife populations can be
 particularly vulnerable to disturbance in alpine habitats as helicopters
 and snowmachines are increasingly used to access remote backcountry
 terrain. Brown bears (Ursus arctos) have adapted hibernation strategies to
 survive this period when resources and energy reserves are limited, and
 disturbance could negatively impact fitness and survival. To help identify
 areas of potential conflict between helicopter skiing and denning brown
 bears in Alaska, we developed a model to predict alpine denning habitat
 and an associated data-based framework for mitigating disturbance
 activities. Following den emergence in spring, we conducted three annual
 aerial surveys (2015–2017) and used locations from three GPS-collared
 bears (2008–2014) to identify 89 brown bear dens above the forest line. We
 evaluated brown bear den site selection of land cover, terrain, and
 climate factors using resource selection function (RSF) models. Our top
 model supported the hypothesis that bears selected dens based on terrain
 and climate factors that maximized thermal efficiency. Brown bears
 selected den sites characterized by steep slopes at moderate elevations in
 smooth, well-drained topographies that promoted vegetation and deep snow.
 We used the RSF model to map relative probability of den selection and
 found 85% of dens occurred within terrain predicted as prime denning
 habitat. Brown bear exposure to helicopter disturbance was evident as
 moderate to high intensities of helicopter flight tracking data overlapped
 prime denning habitat, and we quantified where the risk of these impact
 was greatest. We also documented evidence of late season den abandonment
 due to disturbance from helicopter skiing. The results from this study
 provide valuable insights into bear denning habitat requirements in
 subalpine and alpine landscapes. Our quantitative framework can be used to
 support conservation planning for winter recreation industries operating
 in habitats occupied by denning brown bears.
description: Brown bear den sites were located by aerial survey where latitude
 and longitude coordinates were collected on handheld GPS. Additional den
 sites were located by brown bears instrumented with GPS collars. Habitat
 factors were extracted from the IfSAR dataset and standardized (x-͞x
 /SD(x)) prior to analysis. To estimate resource availability, we generated
 randomly distributed locations at the scale of the study area
 (second-order selection) [82, 83] at a mean density of 500 locations per
 km<sup>2 </sup>[84].
description: Den Data Brown bear (<em>Ursus
 arctos</em>) den site locations in Haines, Alaska, U.S.A.
 (2008-2017). The data file includes fields that were included in the
 analysis of the resource selection function models.  Response of 1
 indicates a den site and 0 indicates an available point. We describe the
 year and geographic mountain range where the den was located, the lifezone
 (alpine, subalpine), elevation (dtm), slope (slope), topographic position
 index (tpi), vegetation height index (vhi), vector ruggedness measure
 (vrm), solar radiation (solrad), terrain wetness index (twi), and snow
 load (snowload). We calculated a snow load factor as the product of two
 elements, elevation scaled (0–1) across the entire range of elevations,
 and a bearing exposure component that was at a maximum opposite from the
 prevalent wind bearing [66]. These habitat factors were scaled (_s) and
 squared (_sq) for analyses. Specific bear den locations
 are confidential under Alaska state law (AS 16.05.815(d)), hence we only
 depict generalized locations. References available in
 the published research article.