The Santa Rita Ranches operate in cooperation with the Santa Rita Experimental Range located to the west of the Santa Rita Mountains, in the upper Santa Cruz Valley. It was established in 1903 and is recognized as a principal site for research on the improvement and management of semiarid grasslands in the Southwest.

Concern has been expressed that mesquite bosques are disappearing or diminishing in quality, and that the survival of the mesquite mouse is consequently threatened. This study, funded by a grant from the Arizona Heritage Fund to the Pima County Regional Flood Control District, investigated the current distribution of the mesquite mouse by reviewing historical records from museum specimens, examining existing potential habitat at historic locations of the species and elsewhere in the county, and conducting a live-trapping study at 19 sites representing a range of ecological communities with mesquite as a major component.