Effects of Wolves on Elk
New report by the Wyoming Game & Fish Department
by Wyoming Game & Fish
March 23, 2007
A report released today (March 23) by the Wyoming Game and Fish Department takes a detailed look at the effects that wolves are having on elk populations in northwestern Wyoming. In the report, department biologists analyzed statewide elk population data from 1980 through 2005.
Wolf reintroduction began in 1995, when the federal government released 14 wolves in Yellowstone National Park. Wolf populations reached recovery goals established by the U.S. Fish and Wildlife Service in 2002 and continue to grow. At the end of 2006, there were an estimated 36 packs in Wyoming, including 311 individual wolves.
To determine the impacts wolves are having on elk, biologists looked at trends in calf:cow ratios over a 26-year period, both in areas where wolf populations have been established and in areas where wolves are not present. Of the 21 elk herds included in the analysis, eight are currently occupied by wolves.
"We have seen a downward trend in many of Wyoming's elk herds over this 26-year period," said Jay Lawson, Game and Fish Wildlife Division Jay Lawson. "That trend is likely due to long-term drought and other habitat related factors. But in half of the herds occupied by wolves, we saw a significantly greater rate of decline after wolves were established compared to herds without wolves. We can't attribute that increased rate of decline to any factor other than wolves."
Biologists feel an elk herd's population can be maintained at objective and provide some hunter harvest when the ratio of calves to cows is around 25 to 100. Once ratios fall below 20:100 there is very little opportunity for hunting. Four elk herds in Wyoming with wolves present have dropped below 25 calves per 100 cows, and two of those herds are below 20 calves per 100 cows. All four herds had declining ratios before wolves were present, but the rate of decline increased significantly after wolves were established. Currently, the only elk herds in the state with recruitment rates that will not support hunting, or possibly even stable populations, are those with significant wolf predation.
"There are a lot of different factors affecting wildlife throughout the state, and wolves are a relatively recent addition to the challenges facing our elk," Lawson said. "We're very concerned about the effects of wolves on the state's elk and reduced hunting opportunities for the public. This report helps us understand how wolves are contributing to changes in our elk herds. We also hope this data will provide us tools to work with federal agencies in charge of wolf management to minimize the effects of wolves on elk and elk hunting opportunities."
The complete report is available in the Game and Fish Web site at http://gf.state.wy.us.