The effects of highway transportation corridors on wildlife: a case study of Banff National Park

Abstract

Road fragmentation is a concern for wildlife viability in and adjacent to protected areas in the Rocky Mountains. Roads create a barrier to wildlife movement and have documented demographic effects, including the alteration of animal communities, the reduction of biological diversity, and the increased threat of extinction. Wildlife movement across and adjacent to the Trans-Canada Highway (TCH) (14,000 annual average daily traffic, AADT) and Highway 1A (3000 AADT) was studied in Banff National Park, Alberta. Animal tracks were observed crossing roadways and on transects adjacent to roads for wolves, cougar, lynx, wolverine, marten, elk, deer, sheep, hare, and red squirrel relative to road types. Data were analyzed to assess the barrier effect and a geographical information system (GIS) was used to identify landscape attributes associated with species movement. The TCH was found to be a barrier to movement for all species. In less perturbed environments, it was observed that movement patterns for the wildlife communities were spatially continuous and that individual species movement was complex. This movement was not observed across the TCH. An interpolation of point data showed sites of high crossing frequency within the continuum of crossing points. These sites ranged from 250 to 2000 m in diameter. General predictors for movement by aspect were found to be the south, southwest and west facing slopes. Flat slopes, areas of low topographic complexity, and slopes lower than 5° were also effective predictors of animal movements. The data suggest that maintaining contiguous tracts of habitat with the above attributes facilitate normal wildlife movement most effectively. Mitigation that approximates previous patterns can be achieved only by elevating and/or burying extensive sections of highway.