Fri Jan 25 00:00:00 MST 2002
The annual interagency Northern Yellowstone Cooperative Elk Count has been completed, and this year's total of 11,969 elk is 11 percent below last year's count of 13,400 elk. Annual elk counts are a group effort by the National Park Service, Montana Fish, Wildlife & Parks, U.S. Geological Survey, and the U.S. Forest Service.
The counts are typically made from four fixed wing airplanes flying the same day over 68 winter range count units inside and outside Yellowstone National Park. This year the surveys spanned a three-day period.
"Survey conditions were good," said Tom Lemke, FWP area biologist from Livingston. "Survey results are direct counts of how many elk were actually observed, and therefore, represent a minimum number of elk in the population."
As with all aerial surveys, not all elk are observable from the planes, Lemke said, however there is no attempt made to correct the number of elk that may be hidden from view.
Northern Yellowstone elk counts have fluctuated by 10 to 30 percent each year, with declines of up to 45 percent following significant winter-kill years such as 1989 and 1997. Since the last major elk winterkill in 1997, the Northern Yellowstone Elk Count has ranged from 11,692 to 14,538 elk. Since 1976, elk counts have ranged from 8,980 to 19,045, with an average of 13,846 elk. The current elk count is within 14 percent of the long-term elk count average, and "well within normal population fluctuations," Lemke said.
Major factors influencing Yellowstone elk numbers include winter severity, predation, hunter harvest, and forage availability. Periodic major winter-kills appear to be the most significant factor affecting Northern Yellowstone elk numbers. In such years, both predation rates and late season hunter harvest may also increase. The recent series of drought years may also affect elk numbers by reducing the amount and quality of available food.
"But, based on elk population counts since 1976, the number of Northern Yellowstone elk is neither abnormally high nor abnormally low," Lemke said.