Effectiveness of above-ground pipeline crossing structures for the movement of moose and other large mammals

Abstract

The purpose of this Master's Degree Project was to evaluate the effectiveness of five above-ground pipeline crossing structures for wildlife movement immediately after pipeline construction near Peace River, Alberta. In order to evaluate the efficacy of pipeline crossing structures, an analysis of the barrier effect created by above-ground pipelines was undertaken first. Twelve months of camera monitoring and one winter of snow tracking were completed in two study areas, one with wildlife crossing structures (structure area), the other without (control area). Black bear, coyote, deer, lynx, moose and wolf were recorded. Above-ground pipelines pose a greater barrier effect on moose given their physical size and life history characteristics. Snow depth, pipeline height, distance to moose habitat, distance to water and distance to road were used to analyze moose movements through Analysis of Variance, t tests, and logistic regressions. Locations where moose deflected away from the pipeline had significantly higher snow depths and distances from water than other movements. Pipeline height is the best predictor of moose crossing locations in the control and structure area. The minimum pipeline height required for moose to cross was 140 cm. Deer and carnivores show a preference to cross pipeline clearances greater than 100 cm and less than 90 cm respectively. Crossing structures facilitate movement across the pipeline and were used more than elevated pipelines by moose and by all species combined. Crossing structures should be placed every 400 m, and be vegetated with a gradient of 6:1 and a width of 4 m on top. Structures that must be placed adjacent to a road should facilitate wildlife movement parallel to the road. The barrier effect created by above-ground pipelines can be more effectively mitigated with large scale efforts. Key Words: Crossing structure, pipeline, wildlife movement, moose, linear development, habitat fragmentation.