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California leaf-nosed bat


The California leaf-nosed bat (Macrotus californicus, MACA) is an insectivorous bat known to occur from the Mojave, Sonoran, and Colorado deserts of the American southwest (southern California, Nevada, and Arizona) and western Mexico. Individuals range in size from 85 to 108 mm total body length and in weight from 12 to 20 g. Individuals are largely sedentary and are active year-round. MACA frequently roosts in cave and mine features near the roost opening, where there is some degree of illumination. MACA prey on relatively large arthropods such as grasshoppers and caterpillars, primarily gleaning prey from the ground or vegetation. In some portions of its range, it has been observed feeding on cactus fruit. This species often forages in riparian and xeric-riparian environments (i.e., desert washes), and has been photographed at Mission Garden (Tucson, AZ) where they feed on caterpillars gleaned from the Garden’s orchard. During the winter MACA requires thermally stable roosts that allow access to warm temperatures. During summer, males and females roost separately, while the sexes roost together during the winter. Some roosts may be occupied year round, particularly those roosts that offer thermally stable and warm winter temperatures.

MACA roosts have been detected on Pima County’s preserves in the Tucson Mountains and upper Altar Valley, though they likely occur more broadly. Historically this species also occupied Colossal Cave in the Rincon Mountains, though its current status there is not known. This species is a federal species of concern and a wildlife species of special concern in Arizona.

Pima County’s bat monitoring objective is to monitor the occupancy, site condition, and associated management needs of a subset of roosts used by the Mexican long-tongued, Lesser long-nosed, California leaf-nosed, and Pale Townsend’s big-eared bats on Pima County open space lands. Monitored roosts will be those roosts that have particular importance to the local population of these four bat species. The County will also work towards documenting all of the known roosts sites for these species that are located on County lands, though not all will be chosen for additional monitoring efforts. Where possible and relevant, results from these inventory and monitoring efforts will be used to guide the management (i.e., gating) and/or restoration of key features that will benefit these and other bat species.

Photo by Scott Robinson (Critter Science)