Assessing the impacts of increasing wolf and grizzly bear populations on the habitat selection and foraging patterns of cougars: A multi-organizational collaborative project in the southern Greater Yellowstone Ecosystem (SGYE)

UC South Ballroom

Across North America and Europe, efforts are underway to restore and conserve populations of top carnivores such as wolves and grizzly bears. These recovering large carnivore populations are reviving long absent competitive interactions amongst species of the same guild, resulting in behavioral shifts by subordinates that can have population and community-level consequences. Despite an impressive body of work on community dynamics following large carnivore recovery, few studies have explored intraguild competition in depth, and much work still needs to be done to understand the dynamics of competitive interactions between large carnivores and their importance to conservation. Following the reintroduction of wolves, and the recovery and expansion of grizzly bears, the Greater Yellowstone Ecosystem (GYE) reclaimed its place as one of the last nearly intact ecosystems in North America, containing a large suite of top carnivores and their ungulate prey. In the southern GYE (SGYE) north of Jackson, Wyoming, management and monitoring of large carnivores and ungulates is complex. Multiple federal and state agencies, as well as non-profit organizations collect data and conduct research on these species. Separate datasets on the population dynamics, movements and food habits of wolves, cougars, and grizzly bears, as well as their primary prey, elk, from 2001 to the present exist. However, none of these single species datasets have been merged or examined comprehensively to date. As such, the SGYE offers a challenging but unique opportunity to study the mechanisms by which recovering large carnivore populations (wolves and grizzly bears) impact subordinate carnivores (cougars) through competition. The aim of this study is to assess the impact of intraguild competition on cougars by investigating key factors driving cougar habitat selection and foraging patterns (i.e. where cougars kill prey), including prey availability, risk of dominant competitor encounter, human activities and other environmental factors. To examine changes in cougar habitat and kill site selection over time and potential drivers of these changes, I will estimate mixed-effects resource selection functions at three spatial scales following a use/availability design using location data from VHF and GPS collared cougars, wolves, grizzly bears and elk and kill site data from cougars. To carry out this project, I developed collaborations with the Interagency Grizzly Bear Study Team, the National Elk Refuge, the National Park Service, the Teton Cougar Project, U.S. Fish and Wildlife Service, and Wyoming Game and Fish Department. Collectively these organizations shared sixteen years of location data on the above-mentioned species for this study, comprising of millions of data points from hundreds of individual animals. This project will advance understanding of how intraguild competition shapes the behavior of cougars, highlighting potential fitness impacts to cougars and subsequent cougar behavioral shifts that could in turn cascade to impact cougar prey species. In an area where management of both carnivores and ungulates remains challenged by a lack of understanding in how shifting community dynamics impact individual species, this study will fill knowledge gaps and aide in the development of conservation and management strategies for both predator and prey species in the GYE.