Skip to content
Home » Projects » Assessing large carnivore dietary interactions in Eastern Washington

Assessing large carnivore dietary interactions in Eastern Washington

The goal of this project was to gain information on the composition and breadth of cougar (Puma concolor) and wolf (Canis lupus) diets to increase our understanding of multi-carnivore dietary interactions in eastern Washington. The project is part of the Washington Predator-Prey Project (WPPP), a collaborative effort between the University of Washington, Seattle (UW) and the Washington Department of Fish and Wildlife (WDFW). The objective of the WPPP is to assess the ecological implications of wolf recolonization in Washington and, in particular, any resulting effects to white-tailed deer (Odocoileus virginianus), mule deer (O. hemionus) and elk (Cervus canadensis) populations.

Our assessment of wolf diets in comparison to cougar diets meets a goal of the wolf-cougar project under the WPPP, which seeks to understand how cougars, a resident top carnivore during wolf absence, are responding to the presence of a novel co-occurring carnivore – the wolf. Wolves traditionally utilize the same or similar prey base as cougars, hunting deer and elk among other mammalian and avian prey species. Given that the Eastern Washington region also supports populations of black bear (Ursus americanus), bobcat (Lynx rufus), coyote, (Canis latrans), lynx (Lynx canadensis), wolverine (Gulo gulo), pine martin (Martes americana) and possibly Cascade red fox (Vulpes vulpes cascadensis), along with goals to reintroduce and/or recover fisher (Pekania pennanti) and Grizzly bear populations (Ursus arctos horribilis), characterizing the diets of co-occurring wolves and cougars is critical to understanding the competing pressures on prey and predator populations created by this rich and diverse carnivore community. 

University of Washington graduate student Lauren Satterfield points to a wolf scat found during fieldwork in eastern Washington in 2019. This scat was one of hundreds collected for metabarcoding diet analysis.

Suspected wolf and cougar scats were collected across two study areas (“Okanogan” and “Northeast”) in Eastern Washington State from 2017-2020 at wolf and cougar feeding and resting sites (also known GPS cluster locations), and opportunistically along roads, trails and off-trail areas hiked while traveling to and from GPS cluster sites. Scats were genetically analyzed in the Levi Genetics Lab at Oregon State University (OSU) using metabarcoding, a cutting-edge genetic approach with high sensitivity to small volumes of DNA, making it ideal for identifying a broad range of prey remains in scat, regardless of prey size. DNA sequences identified in scats were compared to global and regional genetic databases (i.e., GenBank) to identify prey contents to genus or species. Genetic results were used to a) confirm the depositing carnivore (i.e., wolf, cougar, or other); b) determine the vertebrate prey species eaten by wolves and cougars; c) investigate how prey consumption varies by study area and seasonally; d) evaluate dietary differences and overlap between wolves and cougars; and e) combine scat diet results with dietary information from GPS cluster investigations (see below).

Results demonstrated significant overlap in ungulate (deer and elk) prey used by both carnivores, with differences based on study area – mule deer was a primary prey source for both carnivores in the Okanogan study area, and white-tailed deer was the primary prey for both carnivores in the Northeast study area with some additional use of moose by wolves in some packs. Thus, both wolves and cougars primarily prey on deer and both utilize a wide range of other prey species including birds, lagomorphs (e.g., snowshoe hare (Lepus americanus)) and other small mammals, medium mammals (e.g., beaver (Castor canadensis)), and other carnivore species (e.g., coyote). Results are still being analyzed to meet other project objectives. 

Results also add to a wider body of knowledge on carnivore diets, provide new information on large carnivore diets using a novel genetic technique, and allow for comparison of diets across multiple carnivore species sampled by various projects during the same time period and region of Eastern Washington.