More than two decades ago I provided the Pima County Board of Supervisors with testimony regarding desert bighorn sheep on Pusch Ridge in the Catalina Mountains.
The occasion of that testimony was a hearing in which the board was being asked to bless real estate development on the high slopes on the back side of Pusch Ridge. I argued that the proposed developments were essentially in bighorn habitat and that the introduction of houses, people and dogs in that area would have deleterious effects on Pusch Ridge bighorns.
My testimony did not focus on, or even mention, mountain lions or excess brush accumulation resulting from fire control — it focused entirely on people in bighorn habitat. With the exception of then-Supervisor David Yetman, I don’t think anyone on the board heard what I said or cared about it, and the request for development was approved. Less than 15 years later desert bighorn sheep no longer roamed Pusch Ridge.
I do not suggest that this one action by the board was responsible for the demise of the Pusch Ridge herd, but it certainly did not do anything to assure the continued survival of sheep on the ridge — just another nail in the coffin.
I believe Paul Krausmann, then professor of wildlife biology at the University of Arizona, hit the nail on the head when he offered the editorial opinion that desert bighorn sheep are ruminants, and they need to spend a lot of time during the day resting quietly and ruminating. Sheep that are constantly being disturbed by hikers (and their dogs) do not have this opportunity and eventually become weak and sickened and die or become much easier prey to a variety of predators and diseases. It is my opinion that the disappearance of bighorn on Pusch Ridge in the 1990s was a function of continuous interaction with human beings, not brush, not predators, or anything else.
The current effort to re-establish a herd of bighorn on Pusch Ridge is laudable, and I sincerely hope it is ultimately successful although I am pessimistic. I am pessimistic because of the amount of real estate development that has occurred in the upper foothills on both the north and south sides of Pusch Ridge and because of the number of people who hike into the area every week.
The large fires of recent years may have enhanced bighorn habitat with respect to forage availability. I don’t buy the idea that lots of brush made it easier for mountain lions to stalk sheep and, therefore, may have contributed to their disappearance in the 1990s.
Similarly, I do not believe that mountain lion predation will be the ultimate cause of failure of the current reintroduction effort. Unfortunately, mountain lions are being destroyed at present for doing what mountain lions do — eat sheep and deer.
It is my opinion that the creation of a new herd of desert bighorn sheep on Pusch Ridge will not occur until the interaction between humans and sheep on the ridge can be vastly reduced or eliminated. Rules and signs along trails warning hikers to stay on trails are fine, but they are likely to be ignored by enough people that sheep on Pusch Ridge will, once again, be constantly disturbed by human recreationists with the ultimate result of disappearance of bighorn sheep from the Pusch Ridge Wilderness Area.
E. Linwood Smith has been a faculty member at the University of Arizona and Arizona State University, and has spent the last 40 years as a consulting biologist in Tucson. He is currently a senior biologist with WestLand Resources, Inc., and EPG, LLC. Contact him at firstname.lastname@example.org