Lasiurus borealis - Red Bat

Physical Description:

Lasiurus borealis are medium sized bats that range from 93 to 117 mm in total length.  Body length ranging from 40 to 50 mm, and weight ranges from 7 to 13g.  The hind foot is around 6 to 11 mm.  Ear height from notch is 8 to 13 mm.  Forearm length ranges between 36 to 46 mm (Myers & Hatchett 2000).  Color varies from brick red to yellowish red.  Fur is white tipped giving bats a frosted look.  Females appear more frosted while the male posses a more reddish color.  The uropatagium has thick fur, which helps to keep the bat warm (Myers & Hatchett 2000).

Distribution:

Lasiurus borealis inhabits a large portion of the northern U.S. to northern Canada, south through Mexico to Guatemala; also into western South America, and central South America, and onto other islands.  They are rare and almost absent in most of the southeastern U.S. and in deserts of the southwest.

Geographic distribution of Lasiurus borealis.  Figure from NatureServe.org

Ontogeny and Reproduction:

Mating takes place in flight, and in temperate regions it takes place in late summer or fall, sperm is stored over the winter in the uterus, ovulation and fertilization occur in the spring, and births take place form late May to early July (Nowak 1994).  Females give birth to one litter of twins each year, the newborn bats are hairless and weigh about 1.5g.  The young learn to fly at about five weeks old (Myers & Hatchett 2000).

Ecology and Behavior:

Lasiurus borealis like many other bats uses echolocation to find prey.  Phases of long calls with low pulse repetition of narrow bands frequencies are used to located prey.  The bats attack insects, on average, every thirty seconds and are successful usually forty percent of the time.  Hunting for food begins at dusk, with their food consisting of different kinds of insects: moths, beetles, plan-hoppers, ants, flies, and others.  The bats tend to eat more Coleopteran in the early and mid-summer months, but when beetle availably begins to deplete in the late summer the bats tend to feed more on Lepidopteron species (Carter et al. 2004).  Studies show that Lasiurus borealis rarely forge over upland hardwoods habitats (5%) relying instead on bottomland (55%) and (40%) in pine (Carter et al. 2004).    Most of the attacks are done while the bat is airborne.  The type of insect often affects the bats’ echolocation and hunting behaviors, bats adjusting their echolocation calls and attack behaviors to the moths’ clicks (Acharya & Fenton 1992).     A good place to view red bats is under rural streetlights, where you can see a bat dipping and diving for prey (Myers & Hachett 2000).

Lasiurus borealis is a highly migratory bat, sometimes moving south hundreds of miles during fall months.  Migrations are not well documented, but appear likely that from September to November populations in Canada and northern U.S. move south to central and southern United States.  Hibernation may take place during winter months but bats will often awake and forage on warmer days.

Literature Cited:

Acharya, L., and Fenton, M. B. 1992.  Echolocation behaviour of vespertilionid bats (Lasiruus cinerius and Lasiurus borealis) attacking airborne targets including arctiid moth. Canadian Journal of Zoology. 70: 1292-1298.

Carter, T.C., Menzel, M.A., Chapman, B.R., and Miller, K.V. 2004.  Partitioning of Food Resources by Syntopic Eastern Red (Lasiurus borealis), Seminole (L. seminolus) and Evening (Nycticeius humeralis) Bats.  The American Midland Naturalist. 151(1): 186-191.

Myers, P. and J. Hatchett. 2000. “Lasiurus borealis” (On-line), Animal Diversity Web.  At http://animaldiversity.ummz.umich.edu/ssite/accounts/information/Lasiurus_ borealis.html.

NatureServe Explorer at http://www.natureserve.org/explorer. Accessed 21 October 2004).

Nowak, R. 1994. Bats of the World. The Johns Hopkins University Press. 214-217.

 Reference written by Ben Preston, Biology 378 (Mammalogy), University of Wisconsin – Stevens Point.  Edited by Chris Yahnke.  Page last updated August 8, 2005.