Open Collections

White, Peter James

University of British Columbia

Wildlife reintroductions can reshape energetic flows in food webs. After a 150-year absence, plains bison (Bison bison bison) were recently reintroduced to Banff National Park (BNP) to restore the impact of this threatened keystone species. Given their large size and energetic demands, BNP managers anticipated bison to cause reverberating effects on food webs. My research provides a rare opportunity to explore the impacts of this reintroduction on another large herbivore, the Rocky Mountain bighorn sheep (Ovis Canadensis). Understanding the potential for interactions between bison and other sympatric ungulates remains an important factor to determine the future of bison management in BNP. Using GPS collars from 39 sheep and 11 bison, collared between 2018 and 2021, I investigated their resource and spatial use to determine overlap and evaluate three hypotheses: competition, facilitation, and complementarity. Using the competition hypothesis, I predicted sheep would overlap with bison in resource use, but avoid areas spatially. Alternately, the facilitation hypothesis predicted bison and sheep would overlap spatially, select similar resources, and sheep would prefer areas of higher bison utilization. If both species exhibited low spatial and resource overlap, I predicted complementarity. At the population level, bison and sheep exhibited low levels of spatial overlap and there was strong evidence of resource separation in all seasons. In winter, sheep selected for areas of higher bison utilization; however in summer they avoided them. These results did not support the potential for competition or facilitation between bison and sheep and provided the strongest evidence of complementarity. In winter, summer, and fall, results indicated that bison selected areas of higher-quality sheep habitat; as bison populations continue to grow, interactions between these species could increase. To better understand the future impacts of BNP’s bison reintroduction on sheep, managers should: 1) Investigate seasonal diets of both species; 2) Monitor bison use on sheep winter range when resources are more scarce; 3) Evaluate direct displacement interactions; 4) Monitor range health in areas of high bison utilization.

Text

2022-10-28

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/83078

Biology

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/