General Distribution
Distribution of California leaf-nosed bats on southern California National Forest System lands is poorly
known. During 1996-1998 bat surveys were conducted at 76 sites located throughout the four forests of
southern California. These surveys were in partnership with the Biological Resources Discipline within
the U.S. Geological Survey. The taxon was not detected during these bat surveys (Stephenson and
Calcarone 1999). California leaf-nosed bats have reportedly been observed in the Arrastre Creek area of
the San Bernardino Mountains and on the desert side of the San Jacinto Mountains (Stephenson and
Calcarone 1999). In 2002, the U.S. Geological Survey began a series of bat inventory studies in San
Diego County funded by several federal, state, and local agencies including the National Park Service,
United States Forest Service, California Department of Fish and Game, and the County of San Diego.
Four study areas are being surveyed including the Cabrillo National Monument, Descanso Ranger
District of the Cleveland National Forest, Santa Ysabel Ranch Preserve, and the Multi-Species Planning
Area (MSCP) of eastern San Diego County. These efforts have still not detected this species on
National Forest System lands although there are recent observations at nearby Barrett Reservoir.
Systematics
California leaf-nosed bat is the only species of the genus Macrotus that occurs in California. Habitat Requirements
California leaf-nosed bats are strongly associated with desert riparian and wash habitats and favor caves,
mines or cave-like structures (Stokes 2003). Radio-telemetry studies on this species in southern
California deserts showed foraging almost exclusively in desert washes (Brown and others 1993),
although there are a few inland valley/foothill locations in San Diego County (Stokes 2003). Roosts are
generally located in proximity to desert wash areas below elevations of 3,000 feet (914 meters) (Philpott
1997). Night roosting habitat includes buildings, cellars, porches, bridges, rock shelters, and mines
(Philpott 1997). Favored day roosts include mineshafts and caves (Brown pers. comm.).
Long, geothermally heated mine tunnels are utilized for maternity and winter roosts (Berry and Brown
1995). California leaf-nosed bats do not become torpid as do other sympatric bat species, and sustained
exposure to ambient temperatures below 26° C can result in death (Arizona Game and Fish Department
1997). The warmth of the geothermally heated roosts provides a stable year-round temperature of
approximately 29° C (Bell and Fenton 1986), allowing resident California leaf-nosed bats to minimize
energy expenditure during winter as well as summer. Reproduction
Females form maternity colonies and give birth to single young during May and June (Arizona Game
and Fish Department 1997). Young are weaned and become volant in July and August (Bradshaw 1962,
Hoffmeister 1986). Males roost separately during these months but rejoin females in the late summer
and early fall (Arizona Game and Fish Department 1997).
Males congregate at lekking (courtship display) sites in mines and caves. Insemination, ovulation, and
fertilization occur between September and November. Unlike most other bat species in the region,
California leaf-nosed bats do not exhibit delayed implantation (Bleier 1975, Hoffmeister 1986). In this
species, implantation occurs in October-November, but fetal development is slowed or delayed until
March. Daily/Seasonal Activity
Individuals may leave roost sites within 1–3 hours after sunset (Arizona Game and Fish Department
1997). Peak activity occurs after sunset and approximately 2 hours before sunrise (Arizona Game and
Fish Department 1999). This species does not hibernate and is active year-round (Philpott 1997). More
than one diurnal roost site may be used during the year (Philpott 1997). California leaf-nosed bat is a
year-round resident in California (Philpott 1997). Diet and Foraging
California leaf-nosed bats feed primarily on grasshoppers, cicadas, moths, butterflies, dragonflies,
beetles, and caterpillars (Philpott 1997). Prey items are gleaned from the ground or vegetation.
Foraging ranges are small, with most activity within 0.9 mile (1.5 kilometers) of day roosts in winter
months and up to 1.9 miles (3.1 kilometers) during summer months (Brown pers. comm.). This species
does not require drinking water. Moisture requirements are met through consumption of prey (Geluso
1978, Philpott 1997). Territoriality/Home Range
No information is available on territoriality in this species. Predator-Prey Relations
No information is available. Literature Cited
Anderson, S. 1969. Macrotus waterhousii. Mammalian species (1): 1-4.
Arizona Game and Fish Department. 1997. Unpublished abstract compiled and edited by the Heritage
Data Management System, Arizona Game and Fish Department, Phoenix, AZ.
Arizona Game and Fish Department. 1999. Arizona wildlife views (special edition). Phoenix, AZ:
Arizona Game and Fish Department.
Bell, G.; Fenton, M.B. 1986. Visual acuity, sensitivity, and binocularity in a gleaning insectivorous bat,
Macrotus californicus (Chiroptera: Phyllostomidae). Animal behavior 34: 409-414.
Berry, R.D.; Brown, P.E. 1995. Natural history and reproductive behavior of the California leaf-nosed
bat (Macrotus californicus). Bat research news 36(4): 49-50.
Bleier, J.J. 1975. Early embryology and implantation of the California leaf-nosed bat Macrotus
californicus. Anatomical Record 182: 237-253.
Bradshaw, G.V.R. 1962. Reproductive cycle of the California leaf-nosed bat, Macrotus californicus.
Science 136: 645-646.
Brown-Berry, P. 2002. Species account – western Mojave planning area. Bureau of Land Management.
Brown, P.E.; Berry, R.D.; Brown, C. 1993. Foraging behavior of the California leaf-nosed bat,
Macrotus californicus. In: Ecology, conservation, and management of western bat species: Bat species
accounts. Unpublished document distributed at the Western Bat Working Group Workshop, February 9-
13, 1998, Reno, NV.
Geluso, K.N. 1978. Urine concentrating ability and renal structure of insectivorous bats. Journal of
Mammalogy 59: 312-323.
Harvey, M.J.; Altenbach, J.S.; Best, T.L. 1999. Bats of the United States. Arkansas Game and Fish
Commission.
Hoffmeister, D.F. 1986. Mammals of Arizona. Tucson, AZ: University of Arizona Press.
Nevada Bat Working Group. 2001. Species profiles and distribution maps for Nevada bats. [Online].
Available: http://www.batworkinggroups.org/nevada.htm.
Philpott, W. 1997. Summaries of the life histories of California bat species. Unpublished
document. USDA Forest Service, Sierra National Forest, Pineridge Ranger Station.
Stephenson, J.R.; Calcarone, G.M. 1999. Southern California mountains and foothills assessment:
Habitat and species conservation issues. General Technical Report GTR-PSW-175. Albany, CA: Pacific
Southwest Research Station, Forest Service, U.S. Department of Agriculture.
Western Bat Working Group. 1998. Western bat species: Regional priority matrix. Developed at
Western Bat Working Group Workshop, Reno, Nevada, February 9–13, 1998.
Williams, D.F. 1986. Mammalian species of special concern in California. California Department of
Fish and Game, Wildlife Management Division administrative report 86-1.
Zeiner, D.C.; Laudenslayer, W.F., Jr.; Mayer, K.E.; White, M. 1990. California's wildlife. Volume III:
Mammals. California Statewide Wildlife Habitat Relationships System. Sacramento, CA: California
Department of Fish and Game.
Information gathered from California DFG - California Interagency Wildlife Task Group
