General Distribution
Yuma myotis occurs from southwestern British Columbia through the western United States into central
Mexico (Harvey and others 1999). In California this species is found from sea level to over 11,000 feet
(3300 meters), but is uncommon above 8,000 feet (2560 meters) (Zeiner and others 1990). Systematics
Hall (1981) recognized six subspecies of Yuma myotis, two of which occur on southern California
National Forest System lands: M. y. saturatus and M. y. yumanensis. Habitat Requirements
Optimum habitats are characterized by cliffs and rocky walls near desert scrub, pinyon-juniper
woodlands, and other open woodlands and forests. Yuma myotis are commonly found in association
with low elevation reservoirs (Philpott 1997). Open water is a key habitat element for Yuma myotis
(Harvey and others 1999) as they are more closely associated with water than any other North American
species of bat (Barbour 1969).
Yuma myotis is known to roost in buildings, in heavily forested settings (Philpott 1997), in caves, in
mines, under bridges (Harvey and others 1999), in trees (such as hollows in redwood trees), in rock
crevices (Philpott 1997), and in abandoned cliff swallow mud nests (Arizona Game and Fish Department
1999). Reproduction
Mating occurs in fall and fertilization occurs in spring (Arizona Game and Fish Department 1999).
Yuma myotis form large maternity colonies between May and June (Harvey and others 1999). Nursery
colonies form in places that have high, stable temperatures ranging between 86 to 131 degrees
Fahrenheit. Usually assembled in buildings, caves, mines, tree cavities, rock crevices, under bridges, or
beneath the bark of trees, these colonies can contain up to several thousand individuals (eNature.com).
Young are born June–July (Philpott 1997). Daily/Seasonal Activity
Yuma myotis emerge when it is almost dark (Harvey and others 1999). Activity peaks occur 1–2.5
hours after sunset (Zeiner and others 1990). Yuma myotis hibernate and are year-round residents in
California (Philpott 1997). Diet and Foraging
Yuma myotis typically forage just above relatively calm water surfaces, such as ponds, reservoirs, or
pools along streams and rivers (Philpott 1997). This species preys on emergent aquatic insects such as
caddisflies and midges (Philpott 1997). Moths, leafhoppers, June beetles, ground beetles, muscid flies,
and craneflies may also be taken (Easterla and Whitaker 1972). This species has a relatively poor urine
concentrating ability (Geluso 1978), and is frequently observed drinking. Territoriality/Home Range
No information is available. Predator-Prey Relations
Yuma myotis tend to avoid bright moonlight. This behavior may reflect a preference for lunar phobic
insects; it could also be a mechanism to avoid predators such as owls (Arizona Game and Fish
Department 1997). Literature Cited
Arizona Game and Fish Department. 1993. Bats of Arizona. Arizona Wildlife Views (special
edition). Volume 36(8).
Arizona Game and Fish Department. 1997. Myotis yumanensis. 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.
California Department of Fish and Game (Ed.). Living with bats. [Homepage of California Department
of Fish and Game], [Online]. Available: http://www.dfg.ca.gov/gallery/bats.html.
Easterla, D.A.; Whitaker, J.O., Jr. 1972. Food habits of some bats from Big Bend National Park, Texas.
Journal of Mammalogy 53: 887-890.
Federal Register. 1994. Endangered and threatened wildlife and plants; Animal candidate review for
listing as endangered or threatened species, proposed rule. Department of the Interior. Tuesday,
November 15, 1994. 50 CFR Part 17.
Geluso, K.N. 1978. Urine concentrating ability and renal structure of insectivorous bats. Journal of
Mammalogy 59: 312-323.
Hall, E.R. 1981. The mammals of North America. Volume 1. New York: John Wiley & Sons.
Harvey, M.J.; Altenbach, J.S.; Best, T.L. 1999. Bats of the United States. Arkansas Game and Fish
Commission, Arkansas.
Licht, P.; Leitner, P. 1967. Behavioral responses to high temperatures in three species of California
bats. Journal of Mammalogy 48: 52-61.
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.
Tactarian, G. (Ed.). 2001. California bat management plan – Bats in structures. [Homepage of
California bat working group], [Online]. Available: http://home.pacbell.net/tatarian/cbwgdoc.htm.
Tuttle, M.D.; Stevenson, D. 1982. Growth and survival of bats. In: Kunz, T.H., ed. Ecology of
bats. New York: Plenum Publishing Company; 105-150.
Western Bat Working Group. 1998. Western bat species: Regional priority matrix. Developed at
Western Bat Working Group Workshop, Reno, Nevada, February 9–13, 1998.
Zeiner, D.C.; Laudenslayer, W.F., Jr.; Mayer, K.E.; White, M., eds. 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
