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.

With the passage of the Federal Endangered Species Act in 1973, the stage was set for a confrontation between urban development and the provisions of Federal Law. Language was amended to the Act that established standards that a plan would have to meet before the Fish and Wildlife Service could approve it and issue a permit for the take of a listed species. In those jurisdictions that have adopted this approach, conservation of natural resources is no longer an afterthought but a major element that has to be considered during the regular land use permitting process.