Performance indices to identify attributes of highway crossing structures facilitating movement of large mammals

摘要: Studies assessing the efficacy of wildlife crossing structures often lead to spurious results because their failure address masking effects confounding variables. Confounding variables include variation in human activity, density along highway corridor, and equality species' perceived access each structure. We investigated these issues for wide-ranging large carnivores prey species Banff National Park, Alberta, using data obtained from systematic, year-round monitoring 13 newly constructed (underpasses overpasses) 34 months post-construction. standardized first variable by selecting remote areas activity. The second we developing probability models structure usage assuming habitat homogeneity. third species-specific, performance indices (=observed through passage usage–expected usage). regressed against encompassing structural, landscape, Our suggest that absence high activity structural attributes best explained both predator species, while landscape human-related factors were secondary importance. Crossing high, wide short length strongly influenced grizzly bears Ursus arctos, wolves Canis lupus, elk Cervus elaphus, deer Odocoileus sp. More constricted favoured black americanus cougars Puma concolor. Distance cover was most important attribute (negative correlation) a significant factor determining bears, (all positive correlations). findings underscore importance of: (a) integrating temporal spatial variability priori when addressing structures, and; (b) demonstrate respond differently features. In light results, maximize connectivity across roads multiple mammal road construction schemes should diversity mixed size classes. Mitigation planning multiple-species ecosystem is likely be challenging endeavour long-term research will aid decision-making process.