Wolf-Cougar Interactions in Northeast Oregon

Populations of large carnivores are expanding across portions of North America, and sympatric wolves and cougars share habitat, home ranges, and prey resources. These coexisting predators may be subject to interspecific competition and direct interactions between large carnivores are challenging to document due to their cryptic behavior and low population densities. Previous studies have suggested that wolf pack structure provided wolves the advantage in wolf-cougar interactions (i.e. outnumbered), and that the likelihood for wolves to kill cougars is greater than for cougar to kill wolves. Wolves can steal cougar kills, and occasionally kill adult cougars and cougar kittens, suggesting interactions in favor of wolves, and cougar as the subordinate competitor in wolf-cougar systems. However, the effects of competitive interactions with wolves may be limited if cougars exploit alternate prey resources, habitats unoccupied by wolves, or if interactions are rare.

GPS collars have made it possible to collect large, continuous data sets on animals with much less expense and effort than conventional radio-telemetry studies. The frequency at which animal locations are sampled with high precision allow detailed analyses of habitat use, movement patterns, social behavior, territory size, space use, and predation patterns. A technique to estimate predation rates and prey composition using GPS collars was pioneered for cougar by Chuck Anderson and Fred Lindzey. Shortly thereafter, Håkan Sand and colleagues adapted the method to overcome difficulties in finding summer kills for wolves, leading the way in obtaining a more complete picture of wolf predation. The use of GPS collars allows researchers to accurately calculate year round predation rates and prey selection for both wolves and cougar. Estimating accurate predation rates and determining prey selection for wolves and cougars is critical to understanding the role both top predators play in ungulate population dynamics. In addition, GPS collars provide a way to document potentially rare spatial interactions and behavioral responses that might not be observable otherwise.

We are placing GPS collars on both wolves and cougars in the Mt Emily Wildlife Management Unit to identify competitive interactions, predation rates, and prey selection for wolves and cougars in northeast Oregon. This information will be useful in identifying the effects of both carnivores on ungulate population dynamics in northeast Oregon.

 

The Mt Emily Wolf-Cougar Study is a collaborative effort between the Oregon Department of Fish and Wildlife, the Confederated Tribes of the Umatilla Indian Reservation, and Oregon State University. The research project began in the winter of 2014 and will conclude in the summer of 2018.

 

* All information and data presented on this website are preliminary and subject to change. The research project is ongoing and results will not be considered final until completion of the study in the 2018.

A female cougar with a malfunctioning GPS collar that was treed
so the collar could be replaced.  The batteries on the GPS collars
have a lifespan of approximately 15 months.  Once the battery
fails the VHF portion of the collar continues to work so that we are
able to still locate the cougar and replace the collar.



An adult male wolf GPS collared in the Mt Emily WMU.