Movement responses by wolves to industrial linear features and their effect on woodland caribou in northeastern alberta

Abstract

Woodland caribou (Rangifer tarandus caribou) populations are declining across most of their range. Predation by wolves (Canis lupus) is believed to be the main proximate cause of these declines. However, it has been hypothesized that recent forestry and energy sector activity in caribou range ultimately might have caused population declines by altering wolf-caribou relationships. We tested the hypothesis that industrial linear features influence wolf movements in woodland caribou range in northeastern Alberta, resulting in increased wolf-caused caribou mortalities close to these features. Using step selection functions (SSF) and observed vs. simulated wolf movement paths, we found that wolf movement was influenced by natural linear features (rivers and streams) throughout the year, possibly because they provide ease of travel and high prey abundance. Wolf movement was further influenced by industrial linear features, but use of these features differed depending on linetype and season. Wolves showed strong selection for steps closer to conventional seismic lines during the snow-free season. Likewise, observed wolf movement paths followed conventional seismic lines more closely than simulated paths during snow-free months. Use of seismic lines as movement corridors might result in wolves hunting in caribou-preferred habitats (bogs and fens) more frequently than they did historically, particularly in the snow-free season when most caribou mortalities occur. However, we found no evidence that caribou mortalities occurred closer to industrial linear features than did live caribou. We conclude that wolf use of seismic lines increases predation risk for caribou close to these features, resulting in caribou avoidance of linear developments and thus functional loss of otherwise suitable habitat for caribou. ©2011 by the Ecological Society of America.