Impacts of human activity on bighorn sheep in Yellowstone National Park

Abstract

Seventeen years have passed since bighorn sheep (Ovis canadensis canadensis) in Yellowstone National Park (YNP) experienced a massive Chlamydial-caused die-off. Currently, no sign of Chlamydia or pneumonia is evident, thus other factors are considered to be limiting the population. The proposed changes to the Gardiner-Mammoth highway and the highway through Dunraven Pass could increase or decrease human disturbances to the core population of bighorn sheep. Approximately 65% of all observations on the Everts winter range occurred on the top of McMinn Bench (along the proposed road route). One ewe group currently must cross the Gardiner-Mammoth highway to reach spring lambing grounds. The placement of the road onto McMinn Bench would impact at least 2 other populations of ewe groups and 2-3 populations of ram groups, which seek shelter, security, water, and minerals in the cliffs.