Southwestern Desert Bats

Dr. Patricia Brown, Instructor

Dr. Bob Berry, Guest Speaker on Echolocation

CSU San Bernardino, Biology 1019, 18 - 20 May 2007


I.                    Introduction

a.      Nature’s natural pest control, eating 1000s of insects per evening

b.      Lives up to thirty years or more

c.       Speeds up to 40 mph; heights above 5K feet/3K meters; may travel 50 miles/night

d.     Echolocation (pulses of ultrasonic sounds of low diffraction, meaning they bend less) via nose structure or mouth

e.      Doesn’t need water (seeds are primary source)

f.        May look like a rodent, closer to human (see skeleton)

g.      Bats audible hum, purr and chatter


II.                 Taxonomy (Chiroptera, meaning “hand-wing”)

a.      Megachiropteran

                                                              i.      Navigate by echolocation primarily

                                                           ii.      Flying foxes, fruit bats

                                                         iii.      Pollination service, especially agave

b.      Microchiropteran

                                                              i.      Vision may be more primary rather than echolocation (secondary?)

                                                           ii.      Food habitats


III.               Anatomy (vocabulary necessary to identify or key out species)

a.      Nose, rostrum (bridge)

                                                              i.      Leaf structure (delta shape; serves as beam/focus for echolocation)

b.      Keel on calcar; on outer structure (lump on membrane’s edge; wide spot in membrane)

c.       Ears, long or short

d.     Fingers, second, third, fourth, and fifth

e.      Forearm, measurement in millimeters and looking for articulated or non-articulated bones (to determine adult status or sub-adult, juvenile)

f.        Fur color (black, white tips, spots, brown, red, orange, yellow)

g.      Tail, protruding

h.      Tragus above the pena (also used for echolocation)

                                                              i.      Spiked or blunt/clubbed

i.        Baculum (penis bone), useful for male versus female identification

j.        Scat (squishes easily; wood rat rolls)


IV.             Specific Species (* seen in May 2007)

a.      Macrotus californicus (aka California leaf-nose, #2B); short nose; agave specialist; see

b.      * Corynorhinus townsendii (aka Townsend’s big-eared bat, #9A), vulnerable to disturbance—will not tolerate people in roost habitat; prefers to roost close to entrance, so that babies develop faster

c.       * Myotis californicus (aka California myotis, and common around DSC; Salt Creek Hills’ Amargosa Salt Spring Mine, Death Valley at 36° 38.205N 116° 16.578 W, elevation 450 feet); spiked tragus; tail *unexposed (#20A), prefers lower elevations; characteristic frequency, about 50 kHz

d.     Myotis ciliolabrum (aka small footed myotis) tail *exposed (#20B), prefers higher elevations; eats small insects, characteristic, about 40 kHz

e.      * Pipistrellus hesperus (aka Western pip), smallest North American bat (#15A); similar to California Myotis, but can’t store enough fat to hibernate entire winter

f.        Eptesicus fuscus (aka Big brown bat), common to all 48 states, but underappreciated and may be in decline (#15B)

g.      Euderma maculatum (aka spotted bat), rarest bat; first animal FESA listed as “endangered” by F&W; can be heard as a metallic clicking or ticking; Red Rock Canyon

h.      Antrozous pallidus (aka pallid bat), deaf at birth (#9A, Brown’s dissertation)

i.        Leptonycteris curasoae yerbabuenae (aka lesser long-nosed bat),two seen in Riverside county as a vagrant

j.        Myotis velifer likes cottonwood riparian



V.                Social Behavior

a.      Social altruism

                                                              i.      Care for sick and weak

                                                           ii.      Maternal attachment up to nine months

b.      Migratory

                                                              i.      They may not be echo locating

                                                           ii.      Cues may include electromagnetism and sun/moon

c.       Reproductory habitat

                                                              i.      Display area (can be under bridges)

                                                           ii.      Stores semen for months

d.     Maternity Roost

                                                              i.      One pup in spring; twins can be common in some species

                                                           ii.      Thermoregulation

1.      Female colony may be closer to entrance

a.      Males go torpid and can be further back

2.      Birth weight is 1/3 of mother’s weight

a.      Within one month are independent foragers

3.      Temperatures, 19 to 30 degrees C

                                                         iii.      Bat’s milk most nutritious of any mammal

                                                         iv.      Largest known roost, about 250 bats (Myotis thysanodes aka fringed) in Lucky Jim Mine in the Old Woman Mountains

e.      Night Roost

                                                              i.      Species do not roost together

                                                           ii.      In caves, species stay together in different areas

                                                         iii.      Juniper/Pinyon pines

                                                         iv.      Palm Trees

                                                            v.      Cottonwood Trees

f.        Foraging habitat (after sunset; up to 600 meters; needs to be within 3-5 miles of night roost)

                                                              i.      Mosquitoes

                                                           ii.      Moths and butterflies

                                                         iii.      Corn beetle (Texas example of inter-agency cooperation)

                                                         iv.      Desert washes, 100% of the time

                                                            v.      Smoke trees

                                                         vi.      Butterflies/moths

                                                       vii.      Tree lizards

                                                    viii.      Cottonwood riparian (especially Myotis velifer, #21)

g.      Hibernation

                                                              i.      In mines or rock crevasses

                                                           ii.      Lower body temperature to the ambient temperature

1.      Torpor, ranging from low of 1.5 degrees to 11 degrees C

                                                         iii.      Heart rate may drop to once per minute, more commonly 10-20 bpm (may be as high as 210/minute; normal rate is affected by ambient temperatures)

                                                         iv.      Study-able via respirometry (such as RFID or PIT tags which operate on 134.2 kHz and 125 kHz)


VI.             Legal, Ethical, and Medical Issues

a.      Wildlife Management under Federal Endangered Species Act of 1973

                                                              i.      FESA defines species of concern (SC, former category 2 candidate), rare (R), threatened (TR), and fully protected

1.      Big free-tailed bat (SC, 1986)

b.      BATF?

                                                              i.      Guano (from the Quechua 'wanu' via Spanish) with its nitrates and phosphates, can be used for saltpeter

                                                           ii.      War of 1812, The Guano Islands Act of 1856, and the Civil War

c.       Animal Research Committee

                                                              i. (accessed 21 May 2007)

                                                           ii.      Animal Care and Use Manual

d.     Ethical issue: radio transmitters on lactating bats

e.      Federal or State of California Scientific Collecting Permit issued by Department of Fish and Game at (accessed 21 May 2007)

f.        Rabies vaccine (1/10 reported to county Health Department are rabid)

                                                              i.      More likely to get it from dog

                                                           ii.      Wear gloves for larger species

g.      Multi-Species Recovery Plans (MSRP)/Environmental Impact Statements


h.      Division of Occupational Safety and Health and Abandoned Mines (drift mining)

                                                              i.      "gassy," "extra hazardous" or "potentially gassy;"—CO2

                                                           ii.      Collar, the top of the shaft [topo: x inside square], a vertical or incline (see mine safety orders); adit [topo: y on its side in direction of run], horizontal entrance and run; tunnel with two or more portals, openings; wince, interior shaft looking down; rise, interior shaft looking up

                                                         iii.      Inventory, mountain range wide

                                                         iv.      Proper closure (due to hazards, equipment, or collectibles such as explosive gear, pie can (i.e., lunch pails), safety lamps, and hand assay tools)

1.      Exclusion night before a hard closure (i.e., back fill)

2.      Bat friendly, horizontal flight, horizontal bars

3.      Foam filled

i.        DNA primers, mitochondrial DNA 16S ribosomal subunit gene

                                                              i.      Guano contains epithelial cells

                                                           ii.      Wing punching to obtain DNA samples

j.        International migration


VII.          Acoustic Detection, Monitoring, and Recording of Species as well as IDing via Technology

a.      Created by rapidly moving vocal cords

b.      Ultrasonic sounds up to 100-160 kHz; above 20 kHz is difficult or impossible for humans

c.       Constant frequency (CF) or frequency modulation (FM)

d.     Duration is 1-5 milliseconds

e.      Compare activity patterns (search, approach, feeding buzz; see, Fenton and Bell, 1979 and Griffin, 1958); identify species (amateurs have been pressing researchers to distinguish based on differing frequencies); evaluate quality of foraging areas

f.        Types of conversion tools:

                                                              i.      Heterodyne, narrow band looking for a specific bat species

1.      Pettersson Elektronic AB (models 240x or higher) at

                                                           ii.      Frequency division, any call and then dial in by dividing by 16

1.      Titley’s Electronics (e.g., Anabat II) at

2.      Econvergence’s Belfry at

                                                         iii.      Time expansion, slows down the call; miss other calls

                                                         iv.      Binary acoustic technology at (nothing there; accessed 21 May 2007)


VIII.       Trapping for Educational Purposes (Disturbance, Intentional)

a.      Harp Traps

                                                              i.      Vertical piano wires

                                                           ii.      Set in a tunnel

                                                         iii.      Automatic collection; hard to escape

b.      Mist Netting

                                                              i.      6, 9, and 12 meter lengths

                                                           ii.      Isolated pond/surface water


IX.              Man-made Threats to Bats

a.      Disturbance (intentional, banding during hibernation)

b.      Intentional Vandalism

c.       Roosting disturbance or destruction

d.     Man-made water sources (with no escape ramps)

e.      Burning Palm Skirts (especially yellow bats in palms, but red bats on ground)

f.        Public Health concerns (overstating rabies)

g.      Pesticides, notably organochlorine based ones, Malathione and DDT

h.      Loss of riparian habitat

i.        Mine closures and renewals

j.        Bat unfriendly gates

k.      Dams and bridges

l.        Global warming (earlier births?)

m.   Wind Farms

                                                              i.      400-500 foot turbines

                                                           ii.      On private property (access to prove unlikely; 80% scavenging within two days anyway)

                                                         iii.      3500 deaths

                                                         iv.      Especially in late summer and early fall


X.                 Websites

a.      Current Biology, “Barotrauma” at (accessed 5 March 2009)

b.      Bat Conservation International at (accessed 21 May 2007)

c.       “Bats of Orange County” at

d.     “Chiroptera” at

(accessed 21 May 2007)

e.      Federal Endangered Species Act of 1973 at (accessed 21 May 2007)

f.        “Exclusively about bats and caves” at (accessed 21 May 2007)

g.      Western Bat Working Group at (accessed 21 May 2007)

h.      “Transient Behavior, Nocturnal Activity Patterns...,” Journal of Mammalogy (1969) at (accessed 29 May 2007)

                                                              i.      Suggests that “differences in foraging pattern between the sexes was not apparent” (point 7).


XI.              Bibliography

a.      Stephanie Remington, The Distribution and Diversity of Bats in Orange County, California,”  MA Thesis, CSU Pomona, 2000 at

b.      Harvey, Altenbach and Best, Bats of the United States. Little Rock: Arkansas Game and Fish Commission, 1999.

c.       Patricia E. Brown, “Vocal Communication and the Development of Hearing in the Pallid Bat, Antrozous Pallidus,” PhD Dissertation, UCLA, 1973.

d.     “Bat Research News” at

e.      Donald R. Griffin, The Question of Animal Awareness: Evolutionary Continuity of Mental Experience, Revised and enlarged edition.  New York: The Rockefeller University Press, 1981.

f.        Molecular Ecology Notes at (accessed 24 May 2007)

g.      Thomas Nagel, “What is It Like to be a Bat?” The Philosophical Review 83 (1974): 435-450 at

h.      David W. Pearson and Ron Bommarito, Antique Mining Equipment and Collectibles, with Price Guide.  Schiffer Books, 2002.

i.        “Gregory D. Johnson and Edward B. Arnett, A Bibliogrpaphy [sic] Of Bat Interactions With Wind Turbines (2004) at (accessed 13 January 2009).


Compiled: 21 May 2007; revised, 21 May 2007 and 13 January 2009; corrected, 22 and 24 May 2007; 14-15 May 2008.