Carnivore Competition: Spatial and Dietary Implications of Gray Wolf Recolonization for Cougars in Northeast Oregon

• Main Author: Orning, Elizabeth Kari
• Other Authors: Dugger, Katie M., Levi, Taal, Tornquist, Susan, Jones, Julia, Nielson, Ryan, Fisheries and Wildlife
• Format: Doctoral or Postdoctoral Thesis
• Language: English; unknown
• Published: Oregon State University
• Subjects: Canis lupus; gray wolf
• Online Access: https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/m900p119m

After a 40-year absence from Oregon’s landscape, expanding gray wolf (Canis lupus) populations are reestablishing elements of interspecific competition with sympatric large carnivores, like cougars (Puma concolor). This presents new challenges for management of large carnivores and their ungulate prey populations (e.g., elk, Cervus canadensis nelsoni; mule deer, Odocoileus hemionus) in these re-established multi-carnivore systems. Wolf range expansion and interactions with populations of sympatric cougars could alter predation on deer and elk populations in the Pacific Northwest. Competition could also affect the spatial distribution, demography, and population dynamics of cougars, the assumed subordinate predator in wolf-cougar interactions. However, the strength of competitive interactions dictate the trajectory of top-down effects and can be system specific. Coupled with a paucity of empirical data on cougar diets and space use across landscapes with and without wolves, prediction of subsequent effects to prey populations is challenging. Furthermore, the common assumption of additive predation effects when a missing predator is added back to an ecosystem may not be well-founded because elk populations have increased in some parts of the Pacific Northwest. My primary research objectives were to 1) estimate diet composition and kill rates for wolves in northeast Oregon, 2) estimate diet composition and kill rates for cougars and evaluate changes in cougar predation patterns across time periods with and without wolves, 3) evaluate cougar home range and kill site distribution for changes relative to pre-wolf patterns, and 4) investigate the influence of wolf presence on cougar movement patterns and habitat use in northeast Oregon. In addition to addressing key ecological questions about carnivore interactions, results from my research provide information on implications of expanded predator systems for elk and mule deer populations, and will be useful to other states and Canadian provinces in western North ...