Both humans and four-footed predators like to eat elk, but they don't go for the same elk.
Wolves and cougars show a strong preference for elk calves while human hunters generally select elk in the three- to nine-year old range.
That was one of the observations researchers have made in a three-year study of predation by cougars and wolves in Unit 28 in the Salmon Region. The study with preliminary information was presented to the Fish and Game Commission at its January meeting in Boise. The final work may be completed this spring.
This study, the "Lemhi Winter Predator Study", was submitted by Gary Power, Lemhi County Project Coordinator, and Jason Husseman of the University of Idaho's Department of Fish and Wildlife Resources. Cooperators in the study include the Nez Perce Tribe, Idaho Department of Fish and Game, the Rocky Mountain Elk Foundation, U.S. Fish and Wildlife Service, Hornocker Wildlife Institute, World Conservation Society, Salmon-Challis National Forest, BLM, Global Carnivore Fund, University of Idaho, and Lemhi County. The study will be 1 as Husseman's master's thesis.
In three winters, Power and Husseman recorded 214 big game animals killed by cougars and wolves. That included 160 elk, 52 deer, 1 bighorn sheep and one mountain goat. Cougars killed 71 elk, 24 deer, one bighorn and one mountain goat. Wolves killed 89 elk and 28 deer. Both wolves and cougars preferred elk calves, 52 percent of kills by cougars and 58 percent calves by wolves.
Over the three-year period, cougars selected fewer calves and more adult cows. Cougars also began eating more deer and fewer elk, from 14 percent to 41 percent deer while elk consumption went from 83 percent of cougar kills to 56 percent. Wolves' preferences did not change. Researchers also noted that wolves tended to kill both adult and juvenile elk in poorer body condition than did cougars. This may be attributed to hunting methodsÑwolves pursue their prey while cougars are creatures of stealth.
Predators overall favored calves 60 percent of the time, followed by old animals at 25 percent and one- to nine-year-olds 15 percent.
Fish and Game aerial surveys of elk in the unit showed 2,655 elk with 34 calves per 100 cows in 1991. The figures were 4,165 elk with 24 calves per 100 cows in 1996 when wolves were reintroduced. In 1999, the count was 4,435 elk with 24 calves per 100 cows, proportion that stayed the same in 2000. In 2001, there were 3,336-3,600 elk and 19 calves per 100 cows. (The huge Clear Creek forest fire of 2000 may have killed some elk and driven some 300 others out of the unit.)
Elk numbers were highest in 1999 and dropped to pre-1996 levels in 2001. Bull harvest increased 22 percent from 1998 to 2000 in Unit 28. The take of bulls peaked in 1996.
Antlered bulls make up a small portion of wolves' and cougars' kill. The apparent impact on the cow:calf ratio is a matter of considerable interest to the Commission.
Researchers noted that wolf predation seems to be changing elk behavior.
Elk herds now tend to encircle their calves when threatened much like musk oxen do, an effect not seen in this area before wolves came back.