Evaluation of habitat use by a transplanted bighorn sheep herd in Theodore Roosevelt National Park

Nineteen radio-collared California bighorn sheep (14 ewes/5 rams) were transplanted from British Columbia, Canada to the North Unit of Theodore Roosevelt National Park on 26 January 1996 and monitored over the course of a 2-year ecological study of bighorn sheep habitat use.Since their introduction, the transplanted animals have slowly increased their range inside and outside the park boundaries.Actual habitat use was compared to habitat use predicted by a habitat suitability model (Smith et al. 1991).Field observations during the 2-year study generally validated this model suggesting that it could be a useful tool for bighorn sheep management.Sheep activities were focused in the Agronvron smithii-Stipa comata and Artemisia tridentata-Atriplex confertifolia habitat types.Vegetation analysis suggests utilization of areas used by sheep averaged.54% before the study animals moved to other feeding sites.Plant species composition at feeding sites was highly variable.The physiographic type most frequently used by the sheep was the River Breaks.Feeding was heaviest during the mid-morning and late evening hours for most sampling seasons.Bighorn sheep interactions with other ungulate species and predators were frequent and rare, respectively.Sheep generally habituated to the presence of humans.Two sheep occupied areas grazed by cattle.Only 2 sheep occupied ranges near oil development areas.