Most humans are disoriented to some degree by the weird dimensional vastness of the Grand Canyon. It's hard to come to grips with your own comparatively insignificant presence and your high-maintenance needs for survival in the face of a landscape so massive and inhospitable. That's why the sight of a desert bighorn, standing on a ledge just inches wide, calmly contemplating the sweep of the Canyon is so stirring. The bighorn only stand 40 inches tall at the shoulder, but appear completely at ease with their place in the Canyon. They zip from ledge to ledge, seemingly oblivious of the potential for a disastrous fall, focused on finding the sparse desert vegetation that somehow sustains them.
Before the 1800s, desert bighorn numbered in the millions in the Western US, ranging from Canada to Mexico, but hunting, mining, urban development and agriculture diminished those numbers dramatically. Diseases from domestic sheep have long been a threat to the bighorn, as well as direct human interference in their populations from hunters and ranchers wanting to preserve grazing for their herds. In the Grand Canyon, the feral burros that escaped from mining and pioneer outposts were deemed to pose serious competition for the scarce forage in the Canyon, and were removed in the 1980s to give the sheep a better chance.
It's difficult to say with any certainty how many bighorn sheep (of which the desert bighorn are one of two subspecies) exist in the Grand Canyon because the habits and habitat of the bighorn make them a difficult subject to observe.
They can scramble up a sheer cliff face at 15mph, disappearing into terrain completely inaccessible to people. They may be difficult to see even in the open, as this video clip illustrates:
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