Mammal Species of the World
The California leaf-nosed bat, the most northern member of the Phyllostomidae, lives in Northen Mexico, Baja California, southern Arizona, southern California and southern Nevada (Constantine 1998).
Biogeographic Regions: nearctic (Native )
occurs (regularly, as a native taxon) in multiple nations
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: Baja California, Sonora, and northern Sinaloa, Mexico, north to southern California, southern and western Arizona, and southern Nevada (Jones and Carter 1976). Hall (1981) included Tamaulipas and San Luis Potosi in the range of CALIFORNICUS. Northern Sinaloa and southwestern Chihuahua to southern Nevada, southern California; Baja California and Tamaulipas (Koopman, in Wilson and Reeder 1993).
The Macrotus californicus has short broad wings and huge ears and eyes (Tuttle 1998). It's skull has no post orbital processes and a complete premaxillae.
Average mass: 8-17 g.
Average wingspan: 33-35 cm.
Other Physical Features: endothermic ; bilateral symmetry
Average mass: 11.7 g.
Average basal metabolic rate: 0.082 W.
Length: 8 cm
Size in North America
Average: 94.3 mm
Range: 85-99 mm
Range: 12-22 g
Differs from LEPTONYCTERIS and CHOERONYCTERIS in Arizona in having a shorter rostrum, no bristlelike papillae on the tongue, first upper incisor in contact with the canine and usually also in contact with the second premolar, ears joined together near the base, and a larger number of chromosomes (2N=40 vs. 2N=32 or 16) (Hoffmeister 1986). Differs from M. WATERHOUSII by having chromosomes 2N=40 rather than 2N=46, interorbital width of 3.8 mm or less, smaller canines, larger ears, and larger auditory bullae (Davis and Baker 1974, Anderson and Nelson 1965; see also Hoffmeister 1986).
Mojave Desert Habitat
This taxon is found in the Mojave Desert, the smallest of the four North American deserts. While the Mojave lies between the Great Basin Shrub Steppe and the Sonoran Desert, its fauna is more closely allied with the lower Colorado division of the Sonoran Desert. Dominant plants of the Mojave include Creosote Bush (Larrea tridentata), Many-fruit Saltbush (Atriplex polycarpa), Brittlebush (Encelia farinosa), Desert Holly (Atriplex hymenelytra), White Burrobush (Hymenoclea salsola), and Joshua Tree (Yucca brevifolia), the most notable endemic species in the region.
The Mojave’s warm temperate climate defines it as a distinct ecoregion. Mojave indicator species include Spiny Menodora (Menodora spinescens), Desert Senna (Cassia armata), Mojave Indigobush (Psorothamnus arborescens), and Shockley's Goldenhead (Acamptopappus shockleyi). The Mojave supports numerous species of cacti, including several endemics, such as Silver Cholla (Opuntia echinocarpa), Mojave Prickly Pear (O. erinacea), Beavertail Cactus (O. basilaris), and Cotton-top Cactus (Echinocactus polycephalus).
While the Mojave Desert is not so biologically distinct as the other desert ecoregions, distinctive endemic communities occur throughout. For example, the Kelso Dunes in the Mojave National Preserve harbor seven species of endemic insects, including the Kelso Dunes Jerusalem Cricket (Ammopelmatus kelsoensis) and the Kelso Dunes Shieldback Katydid (Eremopedes kelsoensis). The Mojave Fringe-toed Lizard (Uma Scoparia), while not endemic to the dunes, is rare elsewhere. Flowering plants also attract butterflies such as the Mojave Sooty-wing (Pholisora libya), and the widely distributed Painted Lady (Vanessa cardui).
There are a total of eight amphibian species present in the Mojave Desert all of which are anuran species: the endemic Relict Leopard Frog (Lithobates onca); the endemic Amargosa Toad (Anaxyrus nelsoni); Lowland Leopard Frog (Lithobates yavapaiensis); Red-spotted Toad (Anaxyrus punctatus); Southwestern Toad (Anaxyrus microscaphus); Great Basin Spadefoot (Spea intermontana); Great Plains Toad (Anaxyrus cognatus); and the Pacific Treefrog (Pseudacris regilla).
The native range of California’s threatened Desert Tortoise (Gopherus agassizii) includes the Mojave and Colorado Deserts. The Desert Tortoise has adapted for arid habitats by storing up to a liter of water in its urinary bladder. The following reptilian fauna are characteristic of the Mojave region in particular: Gila Monster (Heloderma suspectum NT); Western Banded Gecko (Coleonyx variegatus), Northern Desert Iguana (Dipsosaurus dorsalis), Western Chuckwalla (Sauromalus obesus), and regal horned lizard (Phrynosoma solare). Snake species include the Desert Rosy Boa (Charina trivirgata gracia), Mojave Patchnose Snake (Salvadora hexalepis mojavensis), and Mojave Rattlesnake (Crotalus scutulatus).
Endemic mammals of the ecoregion include the Mojave Ground Squirrel (Spermophilus mohavensis) and Amargosa Vole (Microtus californicus scirpensis); and the California Leaf-nosed Bat (Macrotus californicus).
This species can be found in the caves and abandoned mines in deserts of South West North America. In the winter, they choose roosts that are geothermically heated (Tuttle 1998).
Terrestrial Biomes: desert or dune ; chaparral
Habitat and Ecology
Comments: Lowland desert scrub. Uses caves or abandoned mine tunnels for rest site during day. Small groups may also use natural rock shelters in canyon walls. Uses shelter of open buildings, bridges, rocks, and mines for temporary night roosts. Old mine tunnels or caves may be used as nurseries.
Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
M. californicus is an insectivore. It uses its unuusal hovering ability to capture insects from the ground instead of from the air. It also uses its keen sense of vision over echolocation whenever light is adequate (Bell 1986). They feed up to 1.3km from their roost (Harris 1999).
Foods eaten include: crickets, moths, beetles, and grasshoppers, cicadas and caterpillars.
Animal Foods: insects
Primary Diet: carnivore (Insectivore )
Comments: Eats mainly large, night-flying insects (beetles, grasshoppers, moths) taken in flight and insect larvae, which may be taken from bushes or ground. Flys low, within a meter of the ground, or hovers while foraging. Individuals from southern Arizona and Sonora, Mexico, are known to include fruit in the diet. See Gardner (1977) for further details.
M. californicus plays an important role in insect control.
Known prey organisms
This list may not be complete but is based on published studies.
Usually found roosting in groups, but individuals do not cluster. Males live in small bachelor groups in July and August, join females in September. Has few predators. Maximum life expectancy estimated at more than 10 years (Anderson 1969). Forages up to 1.3 km from roost. Most activity probably closer to roost (Vaughan 1959).
Life History and Behavior
Perception Channels: tactile ; chemical
Comments: Does not hibernate. May be less active during the winter. Rests during the day. Begins to leave daytime roost to forage for food about 1 hour after sunset, returns before sunrise. Rests during the night between periods of activity.
Status: wild: 10.4 years.
Lifespan, longevity, and ageing
During the summer, most males form separate colonies close to female groups of around 100-500 members. However, a handful of dominant males stay within the female colony and have harem groups consisting of 5-25 females and young (Tuttle 1998).
Mating System: polygynous
Mating takes place in the fall. For the first several months of gestation, the embryo develops extremely slowly. Development speeds up in the spring, and young are born in June. (Tuttle 1998).
Breeding season: Mating takes place in the fall, birth in the spring
Range number of offspring: 1 to 2.
Average number of offspring: 1.
Average gestation period: 8 months.
Average weaning age: 1 months.
Average age at sexual or reproductive maturity (female): 6 months.
Average age at sexual or reproductive maturity (male): 12 months.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Average gestation period: 270 days.
Average number of offspring: 1.
Average age at sexual or reproductive maturity (female)
Sex: female: 120 days.
Infants are born with open eyes and ears and a full coat of fur. Infants nurse for one month. While females become sexually mature their first fall, males take a full year to reach sexual maturity (Harris 1999).
Parental Investment: female parental care
Insemination, ovulation, and fertilization occur mainly late September-early October; embryonic development is delayed, gestation lasts about 8 months (Anderson 1969). In Arizona, females usually bear 1 young in May or June. Young are weaned in about 1 month. Females first breed in their first fall, males the following year. Females form maternity colonies.
Molecular Biology and Genetics
Statistics of barcoding coverage: Macrotus californicus
Public Records: 0
Specimens with Barcodes: 7
Species With Barcodes: 1
Populations of this species are definitely decreasing. Human disturbances in caves and the reestablishment of mines is driving these animals out of their homes.
Temperate North American bats are now threatened by a fungal disease called “white-nose syndrome.” This disease has devastated eastern North American bat populations at hibernation sites since 2007. The fungus, Geomyces destructans, grows best in cold, humid conditions that are typical of many bat hibernacula. The fungus grows on, and in some cases invades, the bodies of hibernating bats and seems to result in disturbance from hibernation, causing a debilitating loss of important metabolic resources and mass deaths. Mortality rates at some hibernation sites have been as high as 90%. While there are currently no reports of Macrotus californicus mortalities as a result of white-nose syndrome, the disease continues to expand its range in North America.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
- Cryan, P. 2010. "White-nose syndrome threatens the survival of hibernating bats in North America" (On-line). U.S. Geological Survey, Fort Collins Science Center. Accessed September 16, 2010 at http://www.fort.usgs.gov/WNS/.
- National Park Service, Wildlife Health Center, 2010. "White-nose syndrome" (On-line). National Park Service, Wildlife Health. Accessed September 16, 2010 at http://www.nature.nps.gov/biology/wildlifehealth/White_Nose_Syndrome.cfm.
IUCN Red List Assessment
Red List Category
Red List Criteria
National NatureServe Conservation Status
Rounded National Status Rank: N3 - Vulnerable
NatureServe Conservation Status
Rounded Global Status Rank: G4 - Apparently Secure
Comments: Roosts in mine tunnels and thus vulnerable to their loss or inaccessibility.
Relevance to Humans and Ecosystems
M. californicus, an insectivorous bat, helps to control pest populations.
Positive Impacts: controls pest population
California leaf-nosed bat
The California leaf-nosed bat (Macrotus californicus) is a species of bat in the family Phyllostomidae. It is found in Mexico and the United States. Its natural habitat is hot deserts. It is threatened by habitat loss.
California leaf-nosed bats can be found in Sonoran and Mojave Desert scrub habitats in the Colorado River valley in southern California, Nevada and Arizona, and throughout western Mexico. It is non-migratory and does not hibernate.
The California leaf-nosed bat weighs between 12 and 20 grams, has a wingspan of over 30 centimeters and a body length of over 6 centimeters, and is brown in color. As its name implies, it has a triangular fleshy growth of skin, called a noseleaf, protruding above the nose. This bat is the only bat of the family Phyllostomidae in the United States to have large ears, usually over 2.5 centimeters. It is also one of the most maneuverable in flight. M. californicus seems to spread its uropatagium widely only when hovering or performing other maneuvers requiring a departure from straight level flight, but the extreme maneuverability observed in M. californicus is probably due to the specializations of its sensory equipment. With short, broad wings, it can fly at low speeds using minimal energy. Because of this adaptation, it is not suited for long-distance travel, and is non-migratory.
This bat has an unusual reproductive pattern. After breeding occurs in the fall, the embryos develop very slowly until March, when growth continues at a more normal rate before birth in May or June. Twins are common.
In Macrotus the position of the hind limbs during level flight differs even more form that in most other mammals. The hind limbs are held behind the bat in a spider-leg- like posture, with the femur extending dorsad and caudad, and with the shank partially flexed and extending caudad and more or less downward.
The number of post cervical vertebrae in Macrotus are as follows: twelve thoracic, six lumbar, five sacral, seven caudal.
They are susceptible to human disturbance, which can be especially detrimental to the species during summer months, when these bats are rearing young. Human disturbance of caves in which they roost is a major threat. Furthermore, because they often roost in abandoned mines, reclamation practices and re-working old mines can severely impact populations. Because California leaf-nosed bats do not hibernate or migrate, the relatively warm mine shafts are critical for its survival in the northern portions of its range.
In the study area Macrotus roosts in the daytime exclusively in caves, deserted mine tunnels and deep grottos. They are usually within 30 to 80 feet of the entrance of the tunnel and seem not to require dark retreats. On many occasions, leaf-nosed bats roost in tunnels less than 20 feet deep and fairly brightly lit. In order to be suitable, the Macrotus retreat must be mostly enclosed and have overhead protection from the weather. Roosting chambers are usually large enough to provide considerable ceiling surface and flying space, and thus adequate space allows the animal to find a place to roost while flying. The coolness of the roost also plays a factor in Macrotus selection of roosts, which is why Macrotus would choose to roost in a cool cave in the hot summers. Macrotus prefer to hang from sloping parts of the ceiling and actively grab the rock with ease due to the irregularity of the surface. The bat seems to rest much of the time while hanging onto the rock with only one foot. The free foot is often used for scratching and for grooming the fur, and when the bat is engaged in these activities the body usually swings gently like an erratically disturbed pendulum.
The flight of the Macrotus is remarkable chiefly for its extreme maneuverability. The bat flies fairly rapidly on occasion, but the usual foraging flight is slow and buoyant, and more nearly silent that of most bats. In level flight Macrotus wings make a soft fluttering sound that is less sharp and carrying than the sounds made by the wing beats of most other bats. The method of landing is most interesting. The bat flies six to eight inches below the ceiling and upon the wings making a deep down stoke that is directed nearly straight forward the hind limbs and uropatagium. These movements cause the bat to swoop upward toward the ceiling and as the bat nears the ceiling the wings are pulled back in an upstroke while the bat rolls over 180 degrees so that its back is facing downward and the long legs reach for the ceiling. Stated briefly, then the alighting maneuver consists of an upward swoop and a half-roll, at the end of which the feet wing rapidly toward the ceiling, seize it, and the wings give a final beat to steady the bat. Often these landings must require remarkably precise judgement of speed and distance, as many landings are made in the midst of a fairly closely spaced group of bats. Macrotus has two main methods of launching into flight, by dropping form the ceiling and taking flight after a short downward swoop, and by taking flight directly form the roosting place. The bat often hovers, both when foraging and when flying in its daytime retreat. Macrotus seems to hover easily, and it’s able to hover for several seconds at a time.
This bat is a "gleaning" insectivore which captures prey such as crickets, grasshoppers, beetles, and sphinx moths straight from the ground or foliage rather than in flight. It prefers to use its large eyes to detect prey, although in total darkness it will switch to echolocation. It typically hunts within a few feet of the ground, using its superior eyesight to search for insects. It does not alight to capture its prey, but hovers above it and snags it off the substrate. It then carries its prey to an open roost such as a porch or open building to dismember, then consume it.
These bats usually forage within three feet of the ground and often drop down closer to the ground nearer the surface where they can occasionally hover for a few seconds. Even bats released in the daytime flew fairly close to the ground. Leaf-nosed bats seem to be totally insectivorous, and their food clearly reflects the bats’ foraging habits. Some insects regularly eaten by Macrotus are almost certainly taken from the ground or from vegetation. The bats’ stomachs often contain orthopteran insects, noctuid moths and caterpillars, and beetles of the families Scarabaeidae and Carabidae, along with unidentified material. The lists of food items of Macrotus contain a plethora of insects that seldom fly, are flightless, or that fly in the daytime. This constitutes strong evidence that this bat consumes insects that are on the ground or on vegetation. Most leaf-nosed bats forage sometime between one hour after sundown and four hours after sundown, and then retire to a night roosting place. Each bat seems to have a pre-midnight foraging period of roughly one hour. The greatest activity in the early morning seems to occur between two and one half hours before sunrise and thirty minutes before sunrise. Bats generally begin returning with full stomachs to their daytime roosts about two hours before sunrise, and the last bats usually return approximately twenty minutes before sunrise. A Colony of California Leaf Nosed Bats can consume up to 250,000 pounds of insects in one night.
|Wikimedia Commons has media related to Macrotus californicus.|
- Arroyo-Cabrales, J. & Ticul Alvarez Castaneda, S. (2008). "Macrotus californicus". IUCN Red List of Threatened Species. Version 2009.2. International Union for Conservation of Nature. Retrieved 1 February 2010.
- Vaughan, Terry A. Functional Morphology of Three Bats: Eumops, Myotis, Macrotus. 1st ed. Vol. 12. KC: University of Kansas Museum of Natural History, 1958. Print.
- Steven J. Phillips, Patricia Wentworth Comus (eds.) (2000). A Natural History of the Sonoran Desert. University of California Press. pp. 464–466. ISBN 0-520-21980-5.
- Species Profile at Bat Conservation International. .
- Vaughan, Terry A. Functional Morphology of Three Bats: Eumops, Myotis, Macrotus. 1st ed. Vol. 12. KC: University of Kansas Museum of Natural History, 1958. Print.
- Baker, Robert J., J. Knox. Jones, and Dilford C. Carter. Biology of Bats of the New World Family Phyllostomatidae. Lubbock: Texas Tech, 1976. Print.
Names and Taxonomy
Comments: Considered a subspecies of M. WATERHOUSII by Anderson and Nelson (1965) and Hall (1981). Regarded as a distinct species by Davis and Baker (1974) (based on morphometric and karyotypic evidence); Jones and Carter (1976), Honacki et al. (1982), Jones et al. (1986, 1992), and Koopman (in Wilson and Reeder 1993) followed Davis and Baker (1974) in regarding CALIFORNICUS as a distinct species. See Baker et al. (1989) for a classification of the higher categories of New World Phyllostomidae (relationship of the genus MACROTUS to other members of the family is uncertain). See Van Den Bussche (1992) for an analysis of phylogenetic relationships of phyllostomid bats based on restriction-site variation in the ribosomal-DNA gene complex (MACROTUS regarded as sole member of subfamily Macrotinae).