Kayla Doucette, University of Alberta

The human shield hypothesis suggests that vulnerable species and individuals use human presence as refuge from predators, but this behavioural tactic may oppose the efficacy of management actions that are intended to make animals fearful of people, including aversive conditioning. Aversive conditioning is a management tool that uses repeated negative stimuli to teach animals to associate humans with stressful experiences and thus avoid human-use areas. We hypothesized that subordinate bears use human presence as a shield from dominant bears, which include larger bears for grizzly bears (Ursus arctos horribilis) and all grizzly bears for black bears (U. americanus), and predicted reduced responses to aversive conditioning for subordinate individuals when and where they were in spatial and temporal proximity to dominant individuals in Kananaskis Country, Alberta, Canada. We analyzed time-stamped GPS data for black and grizzly bears collected via observation by wildlife technicians and GPS collars. We defined a series of space-time cubes where grizzly bears occurred within 500-1000 meters and 30-120 minutes of a black bear location. Black bear reactivity to aversive conditioning efforts were scored as resistant, low, or high. Black bears were up to 18% less reactive to aversive stimuli when a grizzly bear was nearby relative to when grizzly bears were absent. These results suggest that black bears are more fearful of grizzly bears than humans exerting aversive stimuli and reveal the need for context-dependent uses of aversive conditioning that maintains the security of individuals from conspecifics while minimizing potential conflict with people.