Surveying and Monitoring Bats in Mines in the Tucson Mountains, with Emphasis on Macrotus californicus and Myotis velifer, 2004-2005

Wolf, Sandy; Dalton, David

The Tucson Mountains are on the western edge of Tucson, Arizona, in the Arizona Uplands Division of the Sonoran Desert (Turner and Brown 1994). Elevations range from about 2,400-4,600 feet. The mountains are managed by National Park Service, Pima County Parks and Recreation, and Bureau of Land Management (BLM). Boundaries are adjacent, so that except for some peripheral areas, the entire mountain range falls under the jurisdiction of these agencies. Although the Tucson Mountains are adjacent to the city of Tucson and contain over 200 abandoned mines, there has been little work conducted on bats in these mountains. There is much yet to learn about the natural history of even common species of bats to make intelligent management decisions that may affect them. For example, a summer bachelor colony of cave myotis (Myotis velifer) has inhabited Wildhorse Mine in Saguaro National Park (SNP) for many years. From census counts, we know that the numbers at the mine vary throughout the summer as well as between years. After gating the mine in 2000, we observed a population decline, but do not have sufficient knowledge about the population’s winter roosts and alternate summer roosts to determine whether the gate was the cause. Our lack of knowledge affects how we interpret observed human impacts on bats, which may in turn affect our management decisions. The purpose of this project was to inventory mines in the Tucson Mountains for use by bats, to monitor colonies of California leaf-nosed bats (Macrotus californicus) and cave myotis to increase our knowledge of the ecology of these species in this area, and to provide information to wildlife managers so they can take appropriate actions to protect roost sites.