Cluster Investigation

Cougar

We monitored 11 GPS-collared cougar over a total of 3,864 cougar-days from July 24, 2014 to November 1, 2016. On average, each cougar was monitored 351 days (range 147 – 525 days). Over this period we investigated 1,563 potential prey acquisition sites. We located remains of 541 prey items at 526 of these sites (34%). Deer remains (mule deer and white-tailed deer, Odocoileous virginianus) were located at approximately 53% of acquisition sites and the remains of elk were located at approximately 40% of prey acquisition sites. The remains of non-ungulate prey were present at the remaining 7% of prey acquisition sites.

Looking only at deer remains, mule deer were the most commonly identified prey items located at prey acquisition sites (73.6%). Remaining deer killed by cougar were white-tailed deer (4.5%) or deer unidentifiable to species (21.8%). Out of all deer remains where we could identify age class, 44.1% were fawns, 28.6% were adults, and 9.5% were yearlings. Of the adult deer where we could identify sex, 27% were bucks and 73% were does.

Of elk remains at cougar acquisition sites where we could identify age class, 71.1% were calves, 9.6% were yearlings, and 14.5% were adults. Of the adult elk remains where we could identify sex, 13% were bulls and 87% were cows.

We identified the remains of non-ungulate prey at prey acquisition sites which included coyote (Canis latrans), beaver (Castor canadensis), domestic goat (Capra aegagrus hircus), domestic sheep (Ovis aries), ruffed grouse (Bonasa umbellus), wild turkey (Meleagris gallopavo), and ground squirrel (Spermophilus spp.). We also located the remains of cougar kittens at 4 sites; two of these events appeared to be abandoned first litters of young sub-adult female cougars with no evidence of predation or infanticide. Two cougar kittens were also found dead with strong evidence of wolf-caused mortality.

Wolves

We evaluated wolf predation over winter (January - March) and summer (June - July) periods from January 2014 to July 2015. We intensively monitored 6 GPS-collared wolves from 3 packs (Mt. Emily, Meacham, Wenaha) over a total of 489 winter wolf-days during 3 winters, defined as January 1 to March 31 (2014-2015). Each wolf was monitored on average 61 days (range 8-97 days). We investigated 456 potential prey acquisition sites over winter study periods. The remains of 115 prey items were located at 112 of these sites (25%). Elk remains were located at approximately 60% of acquisition sites and the remains of mule deer were located at approximately 22% of acquisition sites. The remains of white-tailed deer (7%), unknown deer (9%), and non-ungulate prey (2%) were present at the remaining prey acquisition sites.

Over the winter periods, most of the elk remains that could be identified to age class were calves (49.1%), although adult remains were almost as common (45.6%), with yearlings making up only a small proportion of the remains identified (5.3%). Of the adult elk remains where sex could be determined, 26.1% were bulls and 73.9% were cows. Looking only at deer remains, mule deer were the most commonly identified prey items located at prey acquisition sites (60%). Remaining deer killed by wolves were white-tailed deer (18%) or deer unidentifiable to species (23%). Out of all deer remains where we could identify age class, 59.1% were adults, 31.8% were fawns and 9.1% were yearlings. Of the adult deer where we could identify sex, 55.6% were bucks and 44.4% were does.

We intensively monitored 4 GPS-collared wolves from 2 packs (Mt. Emily, Meacham) over a total of 64 summer wolf-days from June 1-15 and July 1-15 (2014-2015). Each wolf was monitored on average 16 days (range 14-17 days). We investigated 200 potential prey acquisition sites over summer study periods. The remains of 43 prey items were located at 39 of these sites (20%). Elk remains were located at approximately 64% of acquisition sites and the remains of mule deer were located at approximately 17% of acquisition sites. The remains of white-tailed deer (3%), deer unidentifiable to species (3%), and non-ungulate (13%) prey were present at the remaining prey acquisition sites.

Over the summer periods, most of the elk remains where we could identify age class were calves (82.6%), followed by adults (13.0%), and yearlings (4.3%). Of the adult elk remains where we were able to identify sex, all were cows.

Out of all deer remains from summer where we could identify age class, 57.1% were adults, 28.6% were yearlings, and 14.3% were fawns. Of the adult deer where we could identify sex, 33.3% were bucks and 66.7% were does.

We identified non-ungulate prey and scavenging at both winter (2% and 7.8%, respectively) and summer (13.9% and 14%, respectively) prey acquisition sites. Scavenged prey items included native ungulates (elk and mule deer), and non-ungulate prey items included domestic sheep, feral horse (Equus ferus), snowshoe hare (Lepus americanus), and ground squirrel. Cause of death for domestic sheep were ruled “other” by ODFW at the time of investigation and were not considered wolf killed (i.e. died from disease, starvation, old age).

Last updated January 19, 2017