Native to the southwestern U.S. and northwestern Mexico, the desert bighorn sheep is known for its ability to adapt to harsh, arid environments. However, this does not mean the species is immune to the effects of drought. In fact, the fragmented and isolated distribution of the desert mountain ranges that they inhabit means that they can’t follow distant rain storms without traversing broad valleys at significant risk to mortality.
This study examined the effects of a 2002 drought on desert bighorn sheep in the Cabeza Prieta National Wildlife Refuge in southwestern Arizona. Specifically, researchers explored how the drought may have affected habitat selection, behavior, and diet of the sheep. For example, when water is scarce, herbivores such as desert bighorn sheep will sometimes switch their diet to forage more on vegetation with greater water content—the trade-off is that these plants often have a lower nutritional value.
By identifying how desert bighorn sheep responded to a past drought, researchers hoped to identify specific habitat conditions and vegetation that can be used by the species during future droughts, thus contributing to management plans that more effectively protect the long-term survival of the species.