General Distribution
The western red bat occurs in western Canada, western United States, western Mexico, and Central and
South America (Harvey and others 1999). There is little information on the distribution and relative
abundance of this species in southern California (Stephenson and Calcarone 1999). Zeiner and others
(1990) mention roosting habitat is often along edges in woodlands and forests from sea level up through
mixed conifer forests and foraging occurs over a wide variety of habitats. The red bat is locally common
in some areas of California (Zeiner and others 1990). Systematics
There has been a recent splitting into five subspecies of Lasiurus borealis since Shump and Shump
(1982). Taxonomic relationships remain unresolved (Natureserve 2002). Habitat Requirements
The western red bat is associated with large deciduous trees in riparian habitat. It often occurs in
streamside habitats dominated by cottonwood, oaks, sycamore, and walnut (Bolster 1998, Harvey and
others 1999). Foraging occurs in association with streams, forest openings, and clearings.
The western red bat is primarily a solitary species that roosts in the foliage of trees and shrubs in habitats
bordering forests, rivers, cultivated fields, and urban areas (Harvey and others 1999). Stokes (pers.
comm.) mentions that this solitary foliage roosting species typically selects roost sites in riparian trees
such as cottonwood and sycamore. Roost sites are generally hidden from view from all directions
except below; lack obstruction beneath, allowing the bat to drop downward for flight; lack lower perches
that would allow visibility by predators; have dark ground cover to minimize solar reflection and have
nearby vegetation to reduce wind and dust (New Mexico Game and Fish 2000). This species has also
been described as using saguaro cavities and cave-like structures for roosting habitat (Shump and Shump
1982). Reproduction
Western red bat copulation occurs in August and October and may be initiated in flight (Arizona Game
and Fish Department 1999). Fertilization is delayed, occurring the following spring. Females of this
species do not form maternity colonies (Shump and Shump 1982). Western red bat litters range from
one to five young, more than most other bats (Harvey and others 1999). Three is considered average
(Bat Conservation International 2000). Young are born between mid-May and late June (Harvey and
others 1999). Daily/Seasonal Activity
Western red bats are year-round residents in some areas of California (Philpott 1997). It is not known
exactly where western red bats hibernate, though they may burrow into leaf litter or dense grass like
their eastern counterparts (Bat Conservation International 2000). Hibernation may also occur in tree
foliage or tree hollows. Their thick fur, small ears and furred tail help to minimize heat loss.
Western red bats begin foraging approximately 1-2 hours after sunset, with some bats feeding
throughout the night (Arizona Game and Fish Department 1999, Shump and Shump 1982). Diet and Foraging
The diet of western red bat consists of a variety of flying insects such as moths (Harvey and others
1999), but it also includes flies, bugs, beetles, cicadas, ground-dwelling crickets, and hymenopterans
(Arizona Game and Fish Department 1999). Foraging generally begins at high altitude in the air, but
later moves to between tree canopy level and a few feet above the ground (Arizona Game and Fish
Department 1999, Philpott 1997). Stokes (pers. comm.) mentioned western red bats mainly feed on
moths by aerially hawking along edges, over meadows and along riparian courses. Territoriality/Home Range
As reported in Zeiner and others (1990), the western red bat is usually solitary, although nursery
colonies are occasionally found. They foraged from 0.3-0.6 miles from a day roost in Wisconsin. Predator-Prey Relations
Predators of western red bat include opossum (Didelphis virginiana), domestic cat (Felis sylvestris),
sharp-shinned hawk (Accipiter striatus), American kestrel (Falco sparvarius), merlin (Falco
columbarius), great horned owls (Bubo virginianus), and roadrunner (Geococcyx californianus) (Shump
and Shump 1982). Literature Cited
Arizona Game and Fish Department. 1999. Arizona wildlife views: Special edition. Phoenix, AZ:
Arizona Game and Fish Department.
Bat Conservation International. 2002. Bat Conservation International web site, species descriptions.
[Homepage of Bat Conservation International, Inc.], [Online]. Available: http://www.batcon.org/.
Bolster, B.C. 1998. Western red-bat, Lasiurus blossevillii. In: Ecology, conservation and management of
western bat species: Bat species accounts. Unpublished document distributed at the Western Bat
Working Group Meeting, February 9-13, 1998, Reno, NV.
Harvey, M.J.; Altenbach, J.S.; Best, T.L. 1999. Bats of the United States. Arkansas: Arkansas Game and
Fish Commission.
NatureServe Explorer: An online encyclopedia of life. 2002. Version 1.6. Arlington, Virginia, USA:
NatureServe. [Online]. Available: http://www.natureserve.org/explorer/.
New Mexico Game and Fish. 2000. Biota Information System of New Mexico BISON Version 1/2000.
Western Red Bat. [Online]. Available: http://www.fw.vt.edu/fishex/nmex_main/species/050085.htm.
Philpott, W. 1997. Summaries of the life histories of California bat species. Unpublished document.
USDA Forest Service, Sierra National Forest, Pineridge Ranger Station.
Shump, K.A., Jr.; Shump, A.U. 1982. Lasiurus borealis. Mammalian Species 183: 1-6.
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. 1999. Western bat species: Regional priority matrix. Western Bat
Working Group Workshop, February 9-13, 1998, Reno, NV.
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
