When Cougars and Wolves share habitat, Cougars usually occupy higher ground where their stealth style of making a living is optimized.................Most studies have revealed that where Elk and deer exist as prey, wolves will outcompete cougars for elk with cougars dining on deer...............with wolves recolonizing Oregon, it appears that Oregonian Cougars will not be forced to change their diet noticeably to readily coexist with the new canines

Cougars prefer deer over elk, especially fawns and calves

 

Nearly two years after it began, a cougar-predation study in northeast Oregon points to deer as the big cats' preferred fare. Elk are chosen only half as often.Craig Ely, manager of the northeast region for the Oregon Department of Fish and Wildlife, told the state Fish and Wildlife Commission last week the department put radio collars on 28 male and female cougars within the Mt. Emily wildlife management unit, outside of La Grande.

Eighteen collars also had GPS functions allowing researchers to quickly locate kill sites. None of the collared cougars were killed by hunters, but one died on a highway, two were taken because of damage complaints, two slipped their collars,  and three collars either malfunctioned or were on cougars that left the area.

To date, Ely said, department researchers have looked at more than 1,800 kill sites and found 529 prey items.

Deer made up 65 percent of the kills, about half of them fawns.
Elk were found in 30 percent of the sites, three-fourths of them calves. Male cougars killed most of the cow elk discovered.
The remaining 5 percent were smaller animals, and researchers found 24 sites where cougars scavenged meat.
In addition to further evaluating the data, Ely said, the department will use cougar DNA in a mark-recapture formula to see whether biologists can determine populations sizes in the research area. If it works, he said, the state may finally be able to estimate cougar numbers in other wildlife units statewide.