Aggressive Interactions of Rocky Mountain Elk, Cervus elaphus nelsoni, During the Calving Season Toward Mule Deer, Odocoileus hemionus, in Central Colorado


  • Robert M. Stephens Wyoming Game and Fish Department, 528 South Adams Street, Laramie, Wyoming 82070
  • A. William Alldredge 2518 Owl Creek Road, Thermopolis, Wyoming 82443
  • Gregory E. Phillips EDM International, Inc., 4001 Automation Way, Fort Collins, Colorado 80525



Rocky Mountain Elk, Cervus elaphus nelsoni, Mule Deer, Odocoileus hemionus, competition, attack, aggression, interaction


We documented four aggressive interactions between Rocky Mountain Elk (Cervus elaphus) and Mule Deer (Odocoileus hemionus) during the Elk calving season of June and July 1995. In one case, we believe a fawn Mule Deer was killed by two cow Elk. In the other three cases, Elk chased Mule Deer away from an area where they were grazing. These incidents are of interest because documentation of such interactions between Elk and Mule Deer is sparse in the scientific literature and because of the concern about declining Mule Deer populations throughout the western United States.