Building a perceptual zone of influence for wildlife: delineating the effects of roads on grizzly bear movement

To monitor the extent and impact of human disturbances on landscapes and wildlife, managers often estimate zones of influence. Traditionally, zones of influence have been defined with constant width buffers around a disturbance; however, the importance of incorporating variation in landscape contexts and species responses is increasingly recognized. One way to better develop and apply these zones of influence is to understand the mechanisms of animal response to disturbance by examining their sensory detection. We explored the role of perception in wildlife responses to disturbances using a case study with grizzly bears (Ursus arctos) and roads in Alberta, Canada. Our objectives were, first, to model viewsheds and soundscapes around roads and, second, to determine the effect of road perception on grizzly bear movement patterns and build context-specific zones of influence for grizzly bears around roads. Results indicate that zones of influence varied widely between the standard buffer approach and our novel approach based on animal perception. In addition, response distances of bears to roads were greater in areas where roads were perceptible than areas where roads were imperceptible. Estimating a perceptual zone of influence allows managers to prioritize areas for mitigating human disturbances. Our methods may be applied to new disturbances, areas, and species. We recommend measures of perception be used to create more biologically and geographically relevant zones of influence for wildlife.