Annual use of water sources by reintroduced Rocky Mountain bighorn sheep Ovis canadensis canadensis: effects of season and drought

Water sources are important for the conservation and management of bighorn sheep Ovis canadensis (Shaw, 1804). Little is known, however, regarding the use of water by reintroduced Rocky Mountain bighorns O. c. canadensis (Shaw, 1804). Our purpose was to quantify use of water sources by bighorns to test hypotheses related to the value of these sites on Antelope Island, Utah, USA, from July 2005 to December 2006. We predicted that bighorns would increase the number and duration of visits to water during summer. Moreover, we predicted that animals would visit and spend more time at water during drought. Our results indicate that bighorns visited and spent more time around water in summer. These animals, however, did not visit and spend more time at water during drought. Nevertheless, use of water sources increased during times of similar precipitation that followed drought, indicating a potential time-lag in water use by bighorns. Our results underscore the importance of water for reintroduced bighorns in the deserts of western USA, and indicate that animals congregate in riparian areas near water and thereby may facilitate the spreading of diseases and parasites.