Aboveground pipelines (AGP) associated with in-situ oil sands may restrict mammal movement, potentially increasing extinction probability and decreasing reproductive success. Our 12-year study used winter track count techniques to assess the response of winter-active mammals to AGP in northern Alberta, Canada. The primary questions were: which species were most prone to movement obstruction by AGP, facilities or natural factor(s)?; and which factor exerted the strongest influence on crossing likelihood?

A total of 2,068 trails of 12 different species were observed. All species crossed more than half of the time. Focal species crossed on average 80% of the time. Crossing likelihood of white-tailed deer (Odocoileus virginianus), ermine (Mustela erminea), coyote (Canis latrans), lynx (Lynx canadensis), and fisher (Martes pennanti) were significantly influenced by predictors including pipeline height, pipeline corridor width, infrastructure age, vegetation type, and proximity to infrastructure. Deer and lynx crossing likelihood was positively affected by pipe height. Deer, coyote, and ermine crossing likelihood was positively affected by age of pipe. Fisher and deer crossing likelihood was negatively affected by pipeline corridor widths. Our investigations show that most species cross AGP with high crossing frequencies of pipe heights, ranging from 130 cm to 160 cm.

These findings are important for impact mitigation because of the scarcity of published studies of wildlife movement responses to AGP, our inclusion of small and mid-sized carnivores, and our investigation of multiple factors. We highlight mitigation and design improvements, effects of pipeline corridor widths, and challenges posed by coupling infrastructure with pipelines, serving to reduce movement barriers and fragmentation.