Woodland caribou may be an important indicator' or focal species for management agencies because they require large areas to persist and are sensitive to both direct and indirect forms of disturbance. Prior to industrial development in northern regions, it is important to acquire baseline information on areas that are important to local 'herds' as well as to identify physiological and ecological mechanisms of resource selection. I used global positioning system (GPS) data from caribou {Rangifer tarandus caribou), wolves {Canis lupus), and grizzly bears {Ursus arctos), and satellite imagery, resource selection functions, and cause-specific mortality data from 50 caribou neonates to define calving and wintering areas of woodland caribou in northern British Columbia. I identified scale-dependant mechanisms of selection relative to predation risk (calving, summer, winter, and late winter) and forage availability (calving and summer), and energetic costs of movement (winter and late winter) at 2 spatial scales, and quantified the variation in responses to these mechanisms among individual caribou. In all seasons, caribou selected habitats in a hierarchical fashion, and exhibited high variation among individuals. Three unique calving areas, or calving strategies, were defined for the Greater Besa Prophet area; each calving area had different attributes of risk and forage. During calving, spatial separation from areas of high wolf risk was important to parturient females as was access to areas of high vegetative change (i.e., forage quality); animals made trade-off decisions between minimizing the risk of predation and securing forage to address the high nutritional demands of lactation. Calf survival through the first 2 months of life ranged from 54% in 2002 to 79% in 2003. A total of 19 of 50 neonates died during the summers, of which 17 were by predation: wolverines (age of calves <14 d) and wolves (age of calves >18 d) each killed 5 calves. Movements away from calving sites (>1 km) peaked during the third week of life and increased the odds of a neonate surviving by 196%. These movements coincided with a change in vegetative phenology and the high energetic demands of lactation. During winter and late winter, minimizing the energetic costs of movement was the most important parameter in the selection of resources at a smaller spatial scale defined by seasonal movement, whereas Individual caribou showed increased sensitivity to the components of risk at a larger scale of the home range. Variation in the selection of resources by individuals was high, but some similarities facilitated using pooled use/availability data to model resource selection. These pooled models, however, collapsed important biological variation in the selection of resources, limiting biological interpretation of selection models. Variation in the selection of resources among individuals (i.e., plasticity) during all times of the year may be an important life-history strategy for woodland caribou to decrease their predictability on the landscape to major predators. Identifying and maintaining this variation within selection strategies is an important step towards determining the ability of caribou populations to persist in the presence of environmental and anthropogenic disturbance.
My research represents the predator (wolves, Canis lupus, and grizzly bears, Ursus arctos) component of a collaborative endeavor to examine processes that structure the multi-predator multi-prey system of the undisturbed Besa-Prophet watershed in the northern Rocky Mountains, northeastern British Columbia, Canada. It incorporated seasonal movements and range use, resource selection models, and isotopic assessments of prey selection to better understand predator use of the landscape. Mean annual range sizes of five wolf packs and 13 female grizzly bears were 801[plus or minus]118 km² and 334[plus or minus]33 km², respectively. Sizes of annual, denning and late-summer ranges of wolves were proportional to the extent of conifer habitat and related to pack size, whereas winter and late-winter ranges appeared to be a function of movement rates. Most wolf packs used lower elevations during the winter and late-winter seasons and higher elevations during denning, late summers, and fall. Wolves showed highest selection for areas of high habitat diversity. They tended to select shrub habitats year-round and burned habitat classes seasonally, and avoided confer classes. For grizzly bears, sizes of annual home ranges were inversely related to the extent of available Elymus-dominated burns; and seasonal ranges and movement rates were a function of family status. Grizzly bears generally were found at higher elevations during spring, lower elevations during fall, and across elevational gradients during summer. Shrub and burned habitat classes were important to grizzly bears year-round, and conifer classes were consistently avoided. Habitat selection by grizzly bears was best predicted from habitat class, elevation, aspect, and vegetation diversity. Moose (Alces alces) and elk (Cervus elaphus) dominated the diets of wolves. Both male and female grizzly bears increased meat intake (primarily elk) in the fall and males consumed more meat that females throughout the year. Estimates of prey proportions in the diets of wolves and grizzly bears were highly sensitive to the fractionation values incorporated in isotope models. This research provides a comprehensive analysis of habitat selection and habitat use by wolves and grizzly bears that contributes to the long-term management and persistence of these populations.
Snowmachines and the alterations made to the landscape from their activity can have profound impacts on the dynamics of wolves (Canis lupus) and their prey. Snowmachine activity can displace animals and disrupt their activity and movement patterns conversely, the creation of trails can enable energy-efficient travel by wolves, thereby increasing the likelihood of encountering and successfully capturing prey. High hunting and trapping pressure could exacerbate these effects, particular during critical late-winter periods when animals are most stressed and anthropogenic activity is greatest. With its dense network of trails, the Nelchina Basin in south-central Alaska presented a unique opportunity to assess quantitatively the spatial and temporal relationships among wolves, human activity, prey resources, and snow characteristics. I monitored the movements of wolves telemetered with global positioning system (GPS) collars, quantified snowmachine activity using remote-sensing techniques and enumeration counters to delineate the timing and distribution of human use, defined relative moose (Alces alces) abundance using aerial surveys, and routinely measured snow depth and hardness to construct ecologically plausible resource selection models. The seasonal movements, distribution and use areas of wolves in the Nelchina Basin, Alaska, were not influenced consistently by snow or the distribution of prey. Nor did wolves exhibit a strong selection for or an avoidance of linear features (i.e. snowmachine trails, and seismic lines), potentially because responses were confounded by predator-management activities. Levels of recreational snowmachine activity were relatively low and followed predictable patterns by day, week, and season. Wolves appeared to respond to this pressure by using trails when snowmachine activity was least. Wolves travelled 3.7 times faster on trails than off trails, although the proportion of locations specifically on trails was low. Findings from this study suggest that for a heavily exploited wolf
