Disparity in conspecific interaction and vigilance behaviour in a partially-migratory elk herd (Cervus canadensis) on a sympatric winter range
Creators: Trottier, Madeline R.M.
Publisher: name: University of Alberta Library
Year: 2023

<p>Sociality incurs costs and benefits for group-living animals that may influence small-scale behavioural trade-offs such as vigilance and foraging. I examined interaction, vigilance, and foraging behaviours among elk in the partially migratory Ya Ha Tinda elk herd (Cervus canadensis) in Alberta, which exhibits a western migration to montane summer ranges in Banff National Park, while resident elk remain on the sympatric winter range year-round. In recent years, a third eastern migratory tactic has emerged, moving to industrial forest lands east of Ya Ha Tinda during the summer. Previous studies have shown that despite high spatial overlap, western migrants showed different vigilance patterns in areas of human and predation risk than resident elk, which was attributed to differential exposure to predators and humans during the summer. However, the influence of social interactions on foraging and vigilance behaviours among the three migrant tactics is not well known, and it is unknown how eastern elk respond to human and predation risk on the winter range. I examined social interactions at the home range, foraging patch, and individual levels using GPS telemetry data to compare home range overlap and sequential patch use among collared female elk on the winter sympatric range and used direct observations of interaction behaviours in focal elk to assess differences in interaction rates and aggression among individuals. I used behavioural observations to examine the influence of conspecific interactions, predation risk, and human activity on vigilance behaviour during foraging, and the cost of those interactions in terms of time to resume feeding. I determined the influence of environmental factors and where the focal individual was located relative to other elk on the amount of time spent vigilant directly after a conspecific interaction compared to routine vigilance (no interaction), and assessed whether vigilance levels differed among migratory tactics. I found all migrant tactics had a high degree of home range overlap that increased as winter progressed, and migrant elk were more likely to enter foraging patches following resident elk. While interaction rate and duration were similarly low among all tactics, eastern migrants were more aggressive than both western migrant and resident elk. However, interactions made up &lt; 2% of total observation time and disruption times from foraging following interactions were similar among all tactics. Similarly, vigilance bouts were not longer or more frequent following interactions compared to routine vigilance. Instead, vigilance in elk was more strongly related to environmental variables. My study uniquely addresses the influence of conspecific interactions as a differential cost among migrant tactics on a sympatric winter range, and contributes to our understanding of the influence of small-scale behavioural trade-offs on the maintenance of migratory tactics in a partially-migratory population.</p>