Elk Herd Management at the Jackson Hole National Elk Refuge
The modeled population estimate for the Jackson elk herd was 13,356 for 2003-4. From 1989-90 through 2003-4, the herd has ranged from 13,200-18,825 animals. The Wyoming Game and Fish objective remains 11,029 and the department plans to continue to reduce herd size.
During the winter of 2004-5, the total number of elk wintering on and adjacent to the refuge ranged between 5,689 and 6,312. The remainder of the herd winters in Grand Teton National Park, on state feed grounds, and on native winter range. Summer ranges include Grand Teton NP, Bridger Teton National Forest (including the Teton Wilderness), and southern Yellowstone National Park.
Hunting accounts for nearly 90% of adult mortality in the Jackson elk herd. The harvest rate has averaged 20% of the herd during the last 20 years.
Grizzly and black bears, cougars, wolves, and coyotes prey on calves and/or adult elk. The influence of predators may vary from one area to another, at different times, and for different reasons. Amount and quality of habitat, including the availability of winter and transitional range, affect elk numbers, distributions and health.
Winter elk mortality averages 1-2% on the National Elk Refuge because supplemental feed is provided nearly every winter. If supplemental feeding were to be phased back to above average winters only, winter mortality would be expected to range from 1-5%.
Disease can kill elk directly or debilitate animals so that they are more susceptible to predation and severe winter conditions.
Other causes of mortality include natural events, such as drowning, particularly in the spring when water levels are high and elk often fall through ice. Vehicle collisions are also frequent causes of mortality.
These factors interact in complex ways, often making it difficult to determine the cause of population fluctuations.