Populations of desert bighorn sheep across their range declined drastically with European colonization of the American Southwest beginning in the 16th century. These declines were followed by a period of population stabilization ascribed to conservation measures. Desert bighorn sheep numbers remain below historical figures, however the overall population trend has increased since 1960 due to continued conservation efforts.

The bighorn sheep (Ovis canadensis nelsoni) population in the Grand Canyon is one of the largest and most genetically diverse naturally persisting populations of desert bighorn sheep, occupying a very deep canyon with abundant water flowing from the Colorado River.

Even so, bighorn sheep in the Grand Canyon can be affected by threats both inside and outside of the park. Although grazing does not occur in the park, domestic sheep and goat grazing have historically occurred along the park boundaries and has introduced nonnative diseases which can affect park bighorn sheep populations.

Within the park, backcountry recreation from hikers, river runners, and aerial overflights can increase disturbance to bighorn sheep. In addition, changes to Colorado River flows as a result of the Glen Canyon Dam limit bighorn sheep movements across the river. On the largest scale, climate warming and drying can alter habitat quality and forage availability, changing how bighorn sheep move throughout the canyon.

Given all of these threats, the population of bighorn sheep in the Grand Canyon remains comparatively robust and national parks serve as important refugia for regional populations of desert bighorn sheep.

Current Research in Grand Canyon National Park is aimed at understanding the distribution of these animals in the park, and how they are affected by disease.

For a list of related articles about bighorn sheep, Scroll down, past the two videos.