Habitat selection and behavioural strategies of Stone's sheep in northern British Columbia
Dates
Year
2006
Citation
Walker, Andrew B. D., 2006, Habitat selection and behavioural strategies of Stone's sheep in northern British Columbia: University of Northern British Columbia (Canada).
Summary
Baseline information on Stone's sheep (Ovis dalli stonei ) and their habitat is needed because of increased industrial development and recreational activity in the mountains of northern British Columbia. To provide a foundation from which to gauge and mitigate issues relating to access and disturbance, I used global positioning system (GPS) radiotelemetry data acquired from 33 female Stone's sheep in the Besa and Prophet river drainages to develop resource selection functions (RSF) and to define areas important to Stone's sheep. Attributes of topography (slope, aspect, elevation, curvature), vegetation (vegetation type, vegetation quality) and risk of predation from grizzly bears ( Ursus arctos ) and wolves (Canis lupus ) were used [...]
Summary
Baseline information on Stone's sheep (Ovis dalli stonei ) and their habitat is needed because of increased industrial development and recreational activity in the mountains of northern British Columbia. To provide a foundation from which to gauge and mitigate issues relating to access and disturbance, I used global positioning system (GPS) radiotelemetry data acquired from 33 female Stone's sheep in the Besa and Prophet river drainages to develop resource selection functions (RSF) and to define areas important to Stone's sheep. Attributes of topography (slope, aspect, elevation, curvature), vegetation (vegetation type, vegetation quality) and risk of predation from grizzly bears ( Ursus arctos ) and wolves (Canis lupus ) were used to examine seasonal broad-scale habitat selection and interannual variation in selection of attributes by groups of Stone's sheep. Habitat selection was best explained by incorporating vegetation, topography and risk of predation using logistic regression and the information-theoretic approach. Topographic features alone, however, ranked better than components of vegetation or risk of predation in explaining habitat selection and were often excellent predictors of habitat use. Considerable variation existed within selection strategies among groups of Stone's sheep and between years within groups, even though there were general consistencies in selection for steep slopes, ridge-like topography, southerly aspects and upper elevations. Behavioural observations and fine-scale habitat and vegetation measurements were used to characterize intrasexual habitat use of female Stone's sheep relative to maternal status during spring and early summer. Nursery groups spent shorter durations of time active, more time active in solid-rock-escape features, and less time in shrub habitat. The best predictive model using logistic regression to describe differences in habitat use relative to maternal status incorporated distance to nearest-escape feature and size of nearest-escape feature. These intrasexual differences in maternal status were well described by predictions of the predation-risk hypothesis (originally proposed to explain sexual segregation between males and females). Regardless of maternal status, Stone's sheep ewes followed an elevational gradient using low-elevation plant communities in spring and moving up in elevation while tracking plant phenology as the growing season progressed. Fecal samples collected seasonally from two areas that differed in anthropogenic use provided natural variation in stress levels. Fecal glucocorticoid concentrations fluctuated seasonally with higher levels in summer than late winter. Corticosterone was a less variable measure of glucocorticoid concentration than cortisol. This research provides a comprehensive analysis of habitat selection and habitat use by Stone's sheep for which life-history characteristics make them susceptible to environmental and anthropogenic disturbance.
