Factors affecting bighorn sheep activity at water developments in southwestern Arizona

Abstract

Determining the efficacy of artificial water developments for desert bighorn sheep (Ovis canadensis mexicana) populations is an important conservation concern as projected climatic changes pose potentially severe effects to the species in the southwestern United States. We monitored daily visitation frequencies and temporal activity patterns of bighorn sheep at 20 water developments on the Barry M. Goldwater Range-East in Arizona, USA, from January 2015 to December 2018. We evaluated the effects of weather, landscape, and interspecific presence on these data using zero-inflated modeling and temporal activity analysis. Approximately 95% of visits by sheep occurred during summer primarily in response to relatively high temperatures and low precipitation. Conversely, sheep were nearly absent from developments during nonsummer when vegetative moisture was relatively high, especially if temperature was low and precipitation high. The frequency of visits by bighorn sheep increased when interspecifics were present owing to high use of water developments by all species during summer. Bighorn sheep altered their temporal activity to avoid the high activity periods of predators and competitors in all seasons. Water developments with terrain offering antipredator protection also had greater frequencies of visits, but these features did not affect the probability of absence. Overall, our study indicates that water developments provide hydration and thermoregulatory relief to bighorn sheep during the hot and water-limited conditions

Restoration of bighorn sheep: History, successes, and remaining conservation issues

“…Changes in precipitation regimes across western North America may be more dramatic and less predictable than current conditions and could have major implications for management of both natural and artificial water sources (Dolan, 2006;Terry et al, 2022), snowpack and avalanche risk (Conner et al, 2018), forage quantity and quality (Epps et al, 2004), or metapopulation dynamics in desert systems (Epps et al, 2004(Epps et al, , 2006. For instance, in Colorado, increased precipitation increased deposition of inorganic nitrogen, acidifying surface waters and potentially affecting the bottom of the food chain with consequences for bighorn sheep foraging (Williams et al, 2002).…”