Changes in Elk Resource Selection and Distributions Associated With a Late-Season Elk Hunt

ABSTRACT Changes in resource selection associated with human predation risk may alter elk distributions and availability for harvest. We used Global Positioning System data collected from telemetered female elk (Cervus elaphus) to evaluate effects of refuges (areas where hunting was prohibited), spatial variation in hunting risk, and landscape attributes on resource selection within an established Greater Yellowstone Area, USA, winter range. We also evaluated elk distributions during and outside of a late-season hunting period. Refuge areas and landscape attributes such as habitat type and snow water equivalents (SWE) affected resource selection. Elk selection for flat grasslands increased as SWE increased, likely because these areas were windswept, leaving grasses exposed for foraging. Elk distributions differed during hunting and no-hunting periods. During the hunting period, elk shifted to privately owned refuge areas and the estimated odds of elk occupying refuge areas more than doubled. Risk-driven changes in resource selection resulted in reduced availability of elk for harvest. Elk selection for areas where hunting is prohibited presents a challenge for resource managers that use hunting as a tool for managing populations and influences grazing patterns on private ranchlands.     

Autumn resource selection by female elk in a recently burned landscape in western Montana

Wildfire activity across the western United States has increased in recent decades, with wildfires burning at a higher severity and larger scale. The effect of wildfires on forest structure and wildlife habitat is largely influenced by wildfire severity; however, few studies have evaluated the effects of wildfire severity on resource selection of ungulates, particularly during hunting seasons, when knowledge of resource selection is essential for making informed management decisions. To fill this knowledge gap, we fit resource selection probability functions for female elk (Cervus canadensis) in years 2 and 3 post-wildfire to evaluate the effects of wildfire severity and other environmental and anthropogenic factors on elk resource selection during 4 autumn periods with varying levels of hunter pressure (prehunt, archery-only, backcountry rifle, and rifle). The probability of female elk selecting low-severity burned forests during the prehunt, archery-only, backcountry rifle, and rifle periods was 0.99 (95% credible interval [CrI] = 0.98–1.00), 0.99 (CrI = 0.97–1.00), 0.99 (CrI = 0.99–1.00), and 0.0010 (CrI = 0.00067–0.0015]), respectively, and did not strongly differ from the probability of selecting high-severity burned forests. During the prehunt period, elk also selected areas with greater forage quality and areas farther from open roads. Elk selected similar resources during the archery period, and selected areas with higher hunter pressure. Elk started leaving hunting districts that had higher snowpack (i.e., snow water equivalent; β = −0.84, CrI = −0.96–−0.72) and allowed rifle hunting (β = −5.39, CrI = −5.80–−4.97) but still selected areas with higher hunter pressure (β = 0.92, CrI = 0.78–1.07) during the backcountry rifle period. During the rifle period, elk continued avoiding areas with high snowpack (β = −3.96, CrI = −4.22–−3.71) and started selecting areas with lower hunter pressure (β = −1.71, CrI = −1.79–−1.64) and lower canopy cover. Overall, wildfire affected elk distributions in early autumn 2 and 3 years after fire in our study area, with limited differences in resource selection between wildfire severity categories. By late autumn, hunter pressure and snowpack were the primary factors influencing elk distribution, and wildfire had little influence on selection. When estimating wildfire effects on elk movements during autumn and establishing appropriate hunting regulations, managers should consider the hunting season, hunter pressure, timing and amount of snowpack, location of traditional winter range, and the seasonal elk range burned, as all these factors may contribute to how elk use the landscape in autumn.     

Sex and diel period influence patterns of resource selection in elk

Resource selection and space use are important aspects of an animal's ecology and understanding these behaviors is necessary for proper wildlife management. We used mixed-effect integrated step-selection models to evaluate seasonal variation in resource selection between male and female elk (Cervus canadensis) and diel periods in central Pennsylvania, USA. Resource selection varied seasonally, between sexes, and across diel periods. These results demonstrate strong seasonal sexual segregation in resource use, and movements between habitats throughout the day, highlighting the dynamic nature of resource selection by elk and underscoring the importance of considering sexual variation at multiple temporal scales when designing ungulate management strategies. Finally, we developed habitat suitability maps for male and female elk in the Pennsylvania Elk Management Area. Wildlife ecologists and managers must consider multiple sources of variation in habitat use and resource selection, particularly for large mobile species such as elk.     

Habitat Selection of Rocky Mountain Elk in a Nonforested Environment

Abstract: Recent expansions by Rocky Mountain elk (Cervus elaphus) into nonforested habitats across the Intermountain West have required managers to reconsider the traditional paradigms of forage and cover as they relate to managing elk and their habitats. We examined seasonal habitat selection patterns of a hunted elk population in a nonforested high-desert region of southwestern Wyoming, USA. We used 35,246 global positioning system locations collected from 33 adult female elk to model probability of use as a function of 6 habitat variables: slope, aspect, elevation, habitat diversity, distance to shrub cover, and distance to road. We developed resource selection probability functions for individual elk, and then we averaged the coefficients to estimate population-level models for summer and winter periods. We used the population-level models to generate predictive maps by assigning pixels across the study area to 1 of 4 use categories (i.e., high, medium-high, medium-low, or low), based on quartiles of the predictions. Model coefficients and predictive maps indicated that elk selected for summer habitats characterized by higher elevations in areas of high vegetative diversity, close to shrub cover, northerly aspects, moderate slopes, and away from roads. Winter habitat selection patterns were similar, except elk shifted to areas with lower elevations and southerly aspects. We validated predictive maps by using 528 locations collected from an independent sample of radiomarked elk (n = 55) and calculating the proportion of locations that occurred in each of the 4 use categories. Together, the high- and medium-high use categories of the summer and winter predictive maps contained 92% and 74% of summer and winter elk locations, respectively. Our population-level models and associated predictive maps were successful in predicting winter and summer habitat use by elk in a nonforested environment. In the absence of forest cover, elk seemed to rely on a combination of shrubs, topography, and low human disturbance to meet their thermal and hiding cover requirements.     

Effects of Season and Scale on Response of Elk and Mule Deer to Habitat Manipulation

Abstract: Manipulation of forest habitat via mechanical thinning or prescribed fire has become increasingly common across western North America. Nevertheless, empirical research on effects of those activities on wildlife is limited, although prescribed fire in particular often is assumed to benefit large herbivores. We evaluated effects of season and spatial scale on response of Rocky Mountain elk (Cervus elaphus) and mule deer (Odocoileus hemionus) to experimental habitat manipulation at the Starkey Experimental Forest and Range in northeastern Oregon, USA. From 2001 to 2003, 26 densely stocked stands of true fir (Abies spp.) and Douglas-fir (Pseudotsuga menziesii) were thinned and burned whereas 27 similar stands were left untreated to serve as experimental controls. We used location data for elk and mule deer collected during spring (1 Apr-14 Jun) and summer (15 Jun-31 Aug) of 1999–2006 to compare use of treated and untreated stands and to model effects of environmental covariates on use of treated stands. In spring, elk selected burned stands and avoided control stands within the study area (second-order selection; large scale). Within home ranges (third-order selection; small scale), however, elk did not exhibit selection. In addition, selection of treatment stands by elk in spring was not strongly related to environmental covariates. Conversely, in summer elk selected control stands and either avoided or used burned stands proportional to their availability at the large scale; patterns of space use within home ranges were similar to those observed in spring. Use of treatment stands by elk in summer was related to topography, proximity to roads, stand size and shape, and presence of cattle, and a model of stand use explained 50% of variation in selection ratios. Patterns of stand use by mule deer did not change following habitat manipulation, and mule deer avoided or used all stand types proportional to their availability across seasons and scales. In systems similar to Starkey, manipulating forest habitat with prescribed fire might be of greater benefit to elk than mule deer where these species are sympatric, and thus maintaining a mixture of burned and unburned (late successional) habitat might provide better long-term foraging opportunities for both species than would burning a large proportion of a landscape.     

Habitat Selection by Female Elk During Minnesota's Agricultural Season

Understanding space-use patterns by elk (Cervus canadensis) is essential to alleviating human-elk conflicts, particularly when crop depredation by elk can make it harder to justify to the public the need to restore elk populations to regions with agricultural landscapes. In 2016–2017, we used global positioning system data from 20 female elk to investigate their selection for agricultural cover during the agricultural season (1 May–31 Oct) in northwestern Minnesota, USA. We estimated resource selection functions with resource availability defined at the home range scale. Elk space use was primarily determined by distance to forest cover in areas proximate to agricultural fields. During diurnal periods, elk selected areas with forest cover near agricultural fields planted with legumes and cereal. During nocturnal periods, elk selected for agricultural fields with little to no canopy and that were planted with legumes. We suggest that management of elk in northwestern Minnesota will require practices that discourage the use of agriculture by elk while improving natural habitats within areas managed for elk restoration. We suggest that forestry practices (i.e., thinning and burning) could improve cover and forage openings for elk in restoration areas. Furthermore, managers could work with agricultural producers where elk occur to plant crops favored by elk (i.e., legumes) outside known home ranges and plant fields within home ranges with crops that elk avoided (i.e., hay). Collectively, these practices may shift the ranges of elk herds into restoration areas and lower conflict between the public and elk restoration efforts. © 2020 The Wildlife Society.     

A Comparison of Two Modeling Approaches for Evaluating Wildlife-Habitat Relationships

ABSTRACT Studies of resource selection form the basis for much of our understanding of wildlife habitat requirements, and resource selection functions (RSFs), which predict relative probability of use, have been proposed as a unifying concept for analysis and interpretation of wildlife habitat data. Logistic regression that contrasts used and available or unused resource units is one of the most common analyses for developing RSFs. Recently, resource utilization functions (RUFs) have been developed, which also predict probability of use. Unlike RSFs, however, RUFs are based on a continuous metric of space use summarized by a utilization distribution. Although both RSFs and RUFs predict space use, a direct comparison of these 2 modeling approaches is lacking. We compared performance of RSFs and RUFs by applying both approaches to location data for 75 Rocky Mountain elk (Cervus elaphus) and 39 mule deer (Odocoileus hemionus) collected at the Starkey Experimental Forest and Range in northeastern Oregon, USA. We evaluated differences in maps of predicted probability of use, relative ranking of habitat variables, and predictive power between the 2 models. For elk, 3 habitat variables were statistically significant (P < 0.05) in the RSF, whereas 7 variables were significant in the RUF. Maps of predicted probability of use differed substantially between the 2 models for elk, as did the relative ranking of habitat variables. For mule deer, 4 variables were significant in the RSF, whereas 6 were significant in the RUF, and maps of predicted probability of use were similar between models. In addition, distance to water was the top-ranked variable in both models for mule deer. Although space use by both species was predicted most accurately by the RSF based on cross-validation, differences in predictive power between models were more substantial for elk than mule deer. To maximize accuracy and utility of predictive wildlife-habitat models, managers must be aware of the relative strengths and weaknesses of different modeling techniques. We conclude that although RUFs represent a substantial advance in resource selection theory, techniques available for generating RUFs remain underdeveloped and, as a result, RUFs sometimes predict less accurately than models derived using more conventional techniques.     

SCALE-DEPENDENT SUMMER RESOURCE SELECTION BY REINTRODUCED ELK IN WISCONSIN,USA

Abstract: Identifying how habitat use is influenced by environmental heterogeneity at different scales is central to understanding ungulate population dynamics on complex landscapes. We used resource selection functions (RSF) to study summer habitat use in a reintroduced and expanding elk (Cervus elaphus nelsoni) population in the Chequamegon National Forest, Wisconsin, USA. Factors were examined that influenced where elk established home ranges and that influenced habitat use within established home ranges. We also determined grain sizes over which elk responded to environmental heterogeneity and the number of categories of habitat selection from low to high that the elk distinguished. At a large spatial extent, elk home-range establishment was largely explained by the spatial distribution of wolf (Canis lupus) territories. Forage abundance was also influential but was relatively more important at a small spatial extent when elk moved within established home ranges. Areas near roads were avoided when establishing a home-range, but areas near roads were selected for use within the established home range. Elk distinguished among 4 different categories of habitat selection when establishing and moving within home ranges. Spatial and temporal cross validation demonstrated that to improve the predictive strength of habitat models in areas of low inter-annual variability in the environment, it is better to follow more individuals across diverse environmental conditions than to follow the same individuals over a longer time period. Last, our results show that the effects of environmental variables on habitat use were scale-dependent and reemphasize the necessity of analyzing habitat use at multiple scales that are fit to address specific research questions.     

Variation in elk response to roads by season,sex, and road type

Despite the near universal recognition that roads negatively affect wildlife, the mechanisms that elicit animal responses to roads are often ambiguous or poorly understood. We conducted a multi-year, multi-season study to assess the relative influence of roads on elk (Cervus elaphus) in a human-dominated landscape in South Dakota. We evaluated the effects of habitat covariates including security cover, forage quality, distance to roads (primary, secondary, and tertiary), and visibility from roads at the home range scale. We radio-collared 28 elk (21 adult females and 7 adult males) and calculated seasonal (winter, spring, summer, and autumn) utilization distributions (UDs). We assigned habitat covariates to use percentiles within the UDs (1% increments; from 1 to 98 percentiles) and used spatially explicit mixed linear regression to model the relationship between use percentile and habitat covariates. For each season and sex, we evaluated 15 candidate models and used Akaike's Information Criterion weights (ω_i) to identify top-ranking models. We plotted influential coefficients from these models with 95% confidence intervals to examine the magnitude of effects. Our analysis revealed fundamental differences in response to roads, by road type, between sexes, and across seasons. Male elk established home ranges near roads devoid of vehicle traffic in winter, spring, and autumn. In summer, coinciding with peak vehicle traffic levels, male elk reduced their use of habitat that was both visible from and close to primary roads. Female elk subherds similarly responded to primary roads in spring and autumn, during times of year when they were calving and mating, respectively. In spring and summer, female elk subherds selected habitat near roads that were closed to vehicle traffic. Forage quality and security cover were influential in the periphery (>50th use percentile) of elk home ranges, whereas road covariates were more influential towards the core of elk home ranges. This analysis further demonstrates the utility of visibility from road metrics and suggests that the retention of vegetation structures that screen visibility potential from roads could be important components of elk management strategies. © 2012 The Wildlife Society.     

Prioritizing conservation of ungulate calving resources in multiple-use landscapes

Background

Conserving animal populations in places where human activity is increasing is an ongoing challenge in many parts of the world. We investigated how human activity interacted with maternal status and individual variation in behavior to affect reliability of spatially-explicit models intended to guide conservation of critical ungulate calving resources. We studied Rocky Mountain elk (Cervus elaphus) that occupy a region where 2900 natural gas wells have been drilled.

Methodology/Principal Findings

We present novel applications of generalized additive modeling to predict maternal status based on movement, and of random-effects resource selection models to provide population and individual-based inference on the effects of maternal status and human activity. We used a 2×2 factorial design (treatment vs. control) that included elk that were either parturient or non-parturient and in areas either with or without industrial development. Generalized additive models predicted maternal status (parturiency) correctly 93% of the time based on movement. Human activity played a larger role than maternal status in shaping resource use; elk showed strong spatiotemporal patterns of selection or avoidance and marked individual variation in developed areas, but no such pattern in undeveloped areas. This difference had direct consequences for landscape-level conservation planning. When relative probability of use was calculated across the study area, there was disparity throughout 72–88% of the landscape in terms of where conservation intervention should be prioritized depending on whether models were based on behavior in developed areas or undeveloped areas. Model validation showed that models based on behavior in developed areas had poor predictive accuracy, whereas the model based on behavior in undeveloped areas had high predictive accuracy.

Conclusions/Significance

By directly testing for differences between developed and undeveloped areas, and by modeling resource selection in a random-effects framework that provided individual-based inference, we conclude that: 1) amplified selection or avoidance behavior and individual variation, as responses to increasing human activity, complicate conservation planning in multiple-use landscapes, and 2) resource selection behavior in places where human activity is predictable or less dynamic may provide a more reliable basis from which to prioritize conservation action.     

Bark Beetle-Affected Forests Provide Elk Only a Marginal Refuge from Hunters

For nearly 2 decades, the forests of the Rocky Mountains in the United States experienced a bark-beetle (Dendoctronus ponderosae) epidemic. The number of dead and falling trees from this epidemic likely will affect how elk (Cervus canadensis) and hunters use the forest and their interactions. Downed trees potentially create a component of refuge habitat that could affect the effectiveness of hunting to regulate abundance of growing elk populations. We evaluated how forests affected by bark beetles in south-central Wyoming, USA, influenced resource selection of 50 female elk and 374 hunters in 2012–2016, and interactions between elk and hunters. We employed global positioning system (GPS) technology on elk and hunters, and developed a satellite-derived land classification specifically depicting beetle-affected forests. We tested the predictions that elk would increase use of beetle-killed areas from summer to the hunting season, and that hunters would avoid beetle-killed areas regardless of elk use. Elk increased use of beetle-killed areas during hunting seasons as did hunters during the archery season; however, during the rifle season, hunters avoided beetle-killed areas. Nevertheless, during the rifle season, areas of beetle-kill with a high probability of elk occurrence dampened the aversion hunters had towards beetle-killed areas. Therefore, in contrast to our expectations, forests that have been altered by the bark-beetle epidemic may only function marginally as a refuge for elk. Our study area was at the beginning of the tree-fall phase (i.e., ~3–7 yr after peak infestation) of the bark-beetle epidemic; thus, future research efforts should focus on how a continued increase in downed trees will influence interactions between elk and hunters. At current levels of tree fall, however, beetle-kill should not limit the ability of managers to regulate elk herds through harvest. © 2020 The Wildlife Society.     

Female Moose Prioritize Forage Over Mortality Risk in Harvested Landscapes

Since 2010, several moose (Alces alces) populations have declined across North America. These declines are believed to be broadly related to climate and landscape change. At the western reaches of moose continental range, in the interior of British Columbia, Canada, wildlife managers have reported widespread declines of moose populations. Disturbances to forests from a mountain pine beetle (Dendroctonum ponderosae) outbreak and associated salvage logging infrastructure in British Columbia are suspected as a mechanism manifested in moose behavior and habitat selection. We examined seasonal differences in moose habitat selection in response to landscape change from mountain pine beetle salvage logging infrastructure: dense road networks and large intensive forest harvest cutblocks. We used 157,447 global positioning system locations from 83 adult female moose from 2012 to 2016 on the Bonaparte Plateau at the southern edge of the Interior Plateau of central British Columbia to test whether increased forage availability, landscape features associated with increased mortality risk, or the cumulative effects of salvage logging best explain female moose distribution using resource selection functions in an information-theoretic framework. We tested these hypotheses across biological seasons, defined using a cluster analysis framework. The cumulative effects of forage availability and risk best predicted resource selection of female moose in all seasons; however, the covariates included in the cumulative models varied between seasons. The top forage availability model better explained moose habitat use than the top risk model in all seasons, except for the calving and fall seasons where the top risk model (distance to road) better predicted moose space use. Selection of habitat that provides forage in winter, spring, and summer suggests that moose seasonally trade predation risk for the benefits of foraging in early seral vegetation communities in highly disturbed landscapes. Our results identified the need for intensive landscape-scale management to stem moose population declines. Additional research is needed on predator densities, space use, and calf survival in relation to salvage logging infrastructure. © 2020 The Wildlife Society.     

Plasticity in elk migration timing is a response to changing environmental conditions

Migration is an effective behavioral strategy for prolonging access to seasonal resources and may be a resilient strategy for ungulates experiencing changing climatic conditions. In the Greater Yellowstone Ecosystem (GYE), elk are the primary ungulate, with approximately 20,000 individuals migrating to exploit seasonal gradients in forage while also avoiding energetically costly snow conditions. How climate‐induced changes in plant phenology and snow accumulation are influencing elk migration timing is unknown. We present the most complete record of elk migration across the GYE, spanning 9 herds and 414 individuals from 2001 to 2017, to evaluate the drivers of migration timing and test for temporal shifts. The timing of elk departure from winter range involved a trade‐off between current and anticipated forage conditions, while snow melt governed summer range arrival date. Timing of elk departure from summer range and arrival on winter range were both influenced by snow accumulation and exposure to hunting. At the GYE scale, spring and fall migration timing changed through time, most notably with winter range arrival dates becoming almost 50 days later since 2001. Predicted herd‐level changes in migration timing largely agreed with observed GYE‐wide changes—except for predicted winter range arrival dates which did not reflect the magnitude of change detected in the elk telemetry data. Snow melt, snow accumulation, and spring green‐up dates all changed through time, with different herds experiencing different rates and directions of change. We conclude that elk migration is plastic, is a direct response to environmental cues, and that these environmental cues are not changing in a consistent manner across the GYE. The impacts of changing elk migration timing on predator–prey dynamics, carnivore–livestock conflict, disease ecology, and harvest management across the GYE are likely to be significant and complex.     

Seasonal selection and resource dynamics in a seasonally polyphenic butterfly

Seasonal polyphenisms are widespread in nature, yet the selective pressures responsible for their evolution remain poorly understood. Previous work has largely focussed either on the developmental regulation of seasonal polyphenisms or putative ‘top‐down’ selective pressures such as predation that may have acted to drive phenotypic divergence. Much less is known about the influence of seasonal variation in resource availability or seasonal selection on optimal resource allocation. We studied seasonal variation in resource availability, uptake and allocation in Araschnia levana L., a butterfly species that exhibits a striking seasonal colour polyphenism consisting of predominantly orange ‘spring form’ adults and black‐and‐white ‘summer form’ adults. ‘Spring form’ individuals develop as larvae in the late summer, enter a pupal diapause in the fall and emerge in the spring, whereas ‘summer form’ individuals develop directly during the summer months. We find evidence for seasonal declines in host plant quality, and we identify similar reductions in resource uptake in late summer, ‘spring form’ larvae. Further, we report shifts in the body composition of diapausing ‘spring form’ pupae consistent with a physiological cost to overwintering. However, these differences do not translate into detectable differences in adult body composition. Instead, we find minor seasonal differences in adult body composition consistent with augmented flight capacity in ‘summer form’ adults. In comparison, we find much stronger signatures of sex‐specific selection on patterns of resource uptake and allocation. Our results indicate that resource dynamics in A. levana are shaped by seasonal fluctuations in host plant nutrition, climatic conditions and intraspecific interactions.     

Sex-Specific Elk Resource Selection during the Anthrax Risk Period

Anthrax, caused by the spore-forming bacterium Bacillus anthracis, is a zoonosis affecting animals and humans globally. In the United States, anthrax outbreaks occur in wildlife and livestock, with frequent outbreaks in native and exotic wildlife species in Texas, livestock outbreaks in the Dakotas, and sporadic mixed outbreaks in Montana. Understanding where pathogen and host habitat selection overlap is essential for anthrax management. Resource selection and habitat use of ungulates may be sex-specific and lead to differential anthrax exposure risks across the landscape for males and females. We evaluated female elk (Cervus canadensis) resource selection in the same study areas as male elk in a previous anthrax risk study to identify risk of anthrax transmission to females and compare transmission risk between females and males. We developed a generalized linear mixed-effect model to estimate resource selection for female elk in southwest Montana during the June to August anthrax transmission risk period. We then predicted habitat selection of female and male elk across the study area and compared selection with the distribution of anthrax risk to identify spatial distributions of potential anthrax exposure for the male and female elk. Female and male elk selected different resources during the anthrax risk period, which resulted in different anthrax exposure areas for females and males. The sex-specific resource selection and habitat use could infer different areas of risk for anthrax transmission, which can improve anthrax and wildlife management and have important public health and economic implications. © 2020 The Wildlife Society.     

Seasonal habitat use and selection by grizzly bears in Northern British Columbia

We defined patterns of habitat use and selection by female grizzly bears (Ursus arctos) in the Besa-Prophet watershed of northern British Columbia. We fitted 13 adult females with Geographic Positioning System (GPS) radio-collars and monitored them between 2001 and 2004. We examined patterns of habitat selection by grizzly bears relative to topographical attributes and 3 potential surrogates of food availability: land-cover class, vegetation biomass or quality (as measured by the Normalized Difference Vegetation Index), and selection value for prey species themselves (moose [Alces alces], elk [Cervus elaphus], woodland caribou [Rangifer tarandus], Stone's sheep [Ovis dalli stonei]). Although vegetation biomass and quality, and selection values for prey were important in seasonal selection by some individual bears, land-cover class, elevation, aspect, and vegetation diversity most influenced patterns of habitat selection across grizzly bears, which rely on availability of plant foods and encounters with ungulate prey. Grizzly bears as a group avoided conifer stands and areas of low vegetation diversity, and selected for burned land-cover classes and high vegetation diversity across seasons. They also selected mid elevations from what was available within seasonal ranges. Quantifying relative use of different attributes helped place selection patterns within the context of the landscape. Grizzly bears used higher elevations (1,595 ± 31 m SE) in spring and lower elevations (1,436 ± 27 m) in fall; the range of average elevations used among individuals was highest (500 m) during the summer. During all seasons, grizzly bears most frequented aspects with high solar gain. Use was distributed across 10 land-cover classes and depended on season. Management and conservation actions must maintain a diverse habitat matrix distributed across a large elevational gradient to ensure persistence of grizzly bears as levels of human access increase in the northern Rocky Mountains. © 2011 The Wildlife Society.     

Targeting hunter distribution based on host resource selection and kill sites to manage disease risk

Endemic and emerging diseases are rarely uniform in their spatial distribution or prevalence among cohorts of wildlife. Spatial models that quantify risk‐driven differences in resource selection and hunter mortality of animals at fine spatial scales can assist disease management by identifying high‐risk areas and individuals. We used resource selection functions (RSFs) and selection ratios (SRs) to quantify sex‐ and age‐specific resource selection patterns of collared (n = 67) and hunter‐killed (n = 796) nonmigratory elk (Cervus canadensis manitobensis) during the hunting season between 2002 and 2012, in southwestern Manitoba, Canada. Distance to protected area was the most important covariate influencing resource selection and hunter‐kill sites of elk (AICw = 1.00). Collared adult males (which are most likely to be infected with bovine tuberculosis (Mycobacterium bovis) and chronic wasting disease) rarely selected for sites outside of parks during the hunting season in contrast to adult females and juvenile males. The RSFs showed selection by adult females and juvenile males to be negatively associated with landscape‐level forest cover, high road density, and water cover, whereas hunter‐kill sites of these cohorts were positively associated with landscape‐level forest cover and increasing distance to streams and negatively associated with high road density. Local‐level forest was positively associated with collared animal locations and hunter‐kill sites; however, selection was stronger for collared juvenile males and hunter‐killed adult females. In instances where disease infects a metapopulation and eradication is infeasible, a principle goal of management is to limit the spread of disease among infected animals. We map high‐risk areas that are regularly used by potentially infectious hosts but currently underrepresented in the distribution of kill sites. We present a novel application of widely available data to target hunter distribution based on host resource selection and kill sites as a promising tool for applying selective hunting to the management of transmissible diseases in a game species.     

Behavioral responses of male elk to hunting risk

Prey respond to predation risk with a range of behavioral tactics that can vary based on space use and hunting mode of the predator. Unlike other predators, human hunters are often more spatially and temporally restricted, which creates a period of short-duration, high-intensity predation risk for prey. Consequently, identifying the roles different hunting modes (i.e., archery and rifle), hunts for targeted and non-targeted species, and landscape features play in altering spatial and temporal responses of prey to predation risk by humans is important for effective management of harvested populations. From 2009 to 2016, we used a large-scale experiment including 50 animal-years of location data from 38 unique male elk (Cervus canadensis) to quantify changes in movement and resource selection in response to hunters during 3 separate 5-day controlled hunts for antlered males (elk archery, deer [Odocoileus spp.] rifle, and elk rifle) at the Starkey Experimental Forest and Range in northeast Oregon, USA. We evaluated competing hypotheses regarding elk responses to varying levels of prey risk posed by the different hunt types. We predicted that the strength of elk behavioral responses would increase with perceived hunter lethality (i.e., weak response to elk archery but similar response to elk and deer rifle hunts) and that prey response would be closely associated with hunter activity within the diel cycle (greater during diurnal than nocturnal hours) and across hunting seasons. Elk responses were strongest during diurnal hours when hunters were active on the landscape and were generally more pronounced during both rifle hunts than during the archery hunt (supporting our perceived lethality hypothesis). Male elk avoided open roads across all periods except during nocturnal hours of the breeding season and alternated between avoidance of areas with high canopy cover during nocturnal hours and selection during diurnal hours. In combination these patterns led to distinct distributional changes of male elk from pre-hunt to hunt periods. Patterns of male elk selection highlight the importance of managing for heterogeneous landscapes to meet a variety of habitat, harvest, hunter satisfaction, and escapement objectives.     

Spatial and temporal factors influencing sightability of elk

Few tracking studies consider seasonal changes in ability to re-sight wildlife, despite potential for biases in sightability to mislead our interpretation of models of movement and abundance. We developed seasonal sightability models based on visual observations of radio-collared elk (Cervus elaphus) in Manitoba, Canada, through 6 seasons. We located 377 elk 8,862 times using aerial telemetry from 2002 to 2009. We tested the hypothesis that sites where we were able to visually observe radio-collared elk during aerial telemetry differed from sites where collared elk were known to be present but could not be sighted. Relationships varied with season and elk sightability was influenced by forest type, habitat openness, distance to edge, and time of day. Our results confirm that observers have the highest probability of detecting elk in early and late winter. However, factors such as day length, which increases by 64% during this period, suggest that fewer impediments to detection exist in late winter. Our findings reinforce the need to account for seasonal as well as spatial changes in habitat-specific sightability models. © 2011 The Wildlife Society.