Factors affecting bighorn sheep activity at water developments in southwestern Arizona

Abstract

AbstractDetermining 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 non‐summer 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 of summer and sites lacking adequate antipredator terrain limit water development efficaciousness. We also find that temporal partition by sheep potentially reduces fitness during summer and recommend further analysis based on motion‐sensitive cameras to explore this topic.