Project Spotlight: Water Use by Desert Bighorn Sheep and Aoudad

Implementing artificial water sources (e.g., water troughs, guzzlers, and catchments) for wildlife is a prevalent wildlife management practice in the United States. This is thought to enhance water distribution and increase wildlife presence in areas where water is naturally scarce. Since the 1940s artificial water sources have been used as a management tool to restore desert bighorn sheep (Ovis canadensis spp.). By the early 1960s, desert bighorn sheep were extirpated from Texas, and restoration efforts began in the mid-1950s and continue presently. As desert bighorn sheep restoration continues in Texas, desert bighorn sheep are now potentially threatened by aoudad (Ammotragus lervia) distribution and population increase. In addition to possible competition for space and forage, disease transmission between aoudad and desert bighorn sheep is of concern. As aoudad populations continue to increase, research to determine the aoudad’s local ecology is needed to understand this species’ use of water sources. This study evaluated the use of artificial water sources, documenting seasonal and temporal usage by aoudad and desert bighorn in a coexisting area.

Results indicated that water use by desert bighorn sheep is highest in the summer months and significantly decreases in the winter months. Aoudad expressed similar peak utilization in the summer months, but their presence at water sources was widespread throughout all months . Use of artificial water sources by both species differed, as desert bighorn sheep use primarily occurred in late afternoon hours and lacked the crepuscular activity pattern of aoudad. Results revealed differences in water use and gave insight into the time spent utilizing water sources. Although efforts to allocate water sources often target a specific species, other native species also benefit. In this two-year study, the implementation of artificial water sources impacted at least 27 additional wildlife species, as seen on game cameras monitoring the water sites.

While native species benefit from these added water resources, exotic species on the landscape may hinder the use of these resources. Although there is evidence of desert bighorn sheep using such water sources, caution is advised when using artificial water sources for management in areas that aoudad inhabit. The implementation of artificial water sources could increase the likelihood of desert bighorn sheep and aoudad coming into proximity with each other, increasing disease transmission probabilities and possible resource competition.

The use of artificial water sources for wildlife remains a controversial issue. However, results suggest a water management plan could be implemented in which artificial water sources could be active at certain times of the year. For desert bighorn sheep, the summer months are a crucial time to provide water. However, in areas where artificial water sources depend on precipitation events to function (e.g., water guzzlers), year-round aoudad usage and population density could affect water availability for desert bighorn sheep and other native species. Due to the complexity of the issue, efforts for desert bighorn sheep conservation in Texas are currently focused on gaining more data on aoudad and desert bighorn sheep interaction to better understand the impacts aoudad may have on native species and on water use. Finally, more research is underway to help link movements, survival, and interspecific and intraspecific use of resources.