Quantifying barrier effects of roads and seismic lines on movements of female woodland caribou in northeastern Alberta

Linear developments such as roads, seismic lines, and pipeline rights-of-way are common anthropogenic features in the boreal forest of Alberta. These features may act as barriers to the movement of threatened woodland caribou (Rangifer tarandus caribou). Thirty-six woodland caribou were captured and fitted with global positioning system collars. These collared caribou yielded 43 415 locations during the 12-month study period. We compared rates of crossing roads and seismic lines with rates at which caribou crossed simulated roads and seismic lines created using ArcInfo GIS. Seismic lines were not barriers to caribou movements, whereas roads with moderate vehicle traffic acted as semipermeable barriers to caribou movements. The greatest barrier effects were evident during late winter, when caribou crossed actual roads 6 times less frequently than simulated road networks. Semipermeable barrier effects may exacerbate functional habitat loss demonstrated through avoidance behaviour. This novel approach represents an important development in the burgeoning field of road ecology and has great potential for use in validating animal-movement models.