Lasiurus borealis
Red Bat
Physical Description & Characteristics
Adult total length: 3 5/8th - 4 7/8th in. (92 - 122mm), Tail: 1 ½ - 2 ½ in. (38 – 63mm),
Hind foot: 3/8th in. (8.5 – 10mm), and Weight: 1/5th – 3/5th oz. (6 – 14g).
(www.discoverlife.org)
Bats, are unique mammals due to many characteristics: usage of both legs and wings
during flight, elongated fingers to provide wing membrane support, keeled sternums for
enlarged flight muscle attachment, partially fused vertebrae, forelimbs specialized for
true flight, and flight membranes that are extensions of the back and belly and connect
the body with the wings, legs, and tail.
Lasiurus borealis, The Eastern Red Bat’s fur contrasts significantly in colour between the
sexes. Male fur is generally bright red-orange or brick red to rusty red with a narrow
band of red below and a larger band of yellow below that. Guard hairs are generally
white tipped producing a slight frosted effect. Females are a dull buff-chestnut colour
with white frosting. Both males and females have a yellowish-white patch on the front of
each shoulder. The membrane extending from the tail to the hind legs is known as the
interfemoral membrane. The dorsal surface of this membrane is thickly furred. The ears
are short, broad, and rounded and when laid forward reach slightly more than halfway
from the angle of the mouth to the nostrils. The basal two-thirds of the ears are densely
furred. A completely furred uropatagium with the Patagium black and furred from body
and elbow and along forearm is exhibited. The wings are long and narrow with general
wingspan measurements between 11 to13 inches in width. Short, rounded, ears are
visible and white markings are visible on shoulders and wrists. (www.batcow.org, Tuttle
2002)
The species’ mottled red coat protects it by giving the bat an appearance similar to a dead
leaf. This works as camouflage and accounts of Lasiurus borealis have been found
hibernating on the ground in piles of leaf litter. They also hang from tree branches or tree
leaf petioles which can camouflage them as rotting fruit. They often prefer peach trees.
(www.batcow.org, Tuttle 2002)
Economic Importance for Humans
Positive Aspects
Red bats almost never enter human habitation. It is rare to find Lasiurus borealis
invading anthropogenic residential homes. They aid in keeping various insect
populations (particularly mosquitos) low. (www.batcow.org, Tuttle 2002)
Negative Aspects
Some humans view Lasiurus borealis and other bat spp. as threats. Humans should be
aware that bats are capable of transmitting two diseases to humans – Rabies (causative
agent a Rhabdovirus) and Histoplasmosis. Histoplasmosis is a disease caused by inhaling
dust that contains contaminated spores. stated: "Less than a half of 1 percent of bats
contract rabies, a frequency no higher than that seen in many other animals. Like others,
they die quickly, but unlike even dogs and cats, rabid bats seldom become aggressive." A
misnomer is that bats attack when they get rabies, this is false as they are stagnant and
reside, unmoving, in one place. It is rare for humans to contract rabies from infected bats.
People handling bats should be aware of this possibility and take necessary precautions.
(Tuttle, 1988), (http://biology.usgs.gov), (www.discoverlife.org, Fenton and Becht 2002)
Conservation
The heritage status of Lasiurus borealis is “G5: Secure-Common, widespread, and
abundant (although it may be rare in parts of its range, particularly on the periphery). Not
vulnerable in most of its range, and with considerably more than 100 occurrences and
more than 10,000 individuals.”
-IUCN Category: This species has not been evaluated or is considered of Lesser
Concern by the IUCN.
-CITES Status: Not currently listed by CITES
(www.natureserve.org, Wilson and Reeder 1993, Reed 1997, Hall 1992).
L. borealis occur throughout much of eastern North America, generally east of the
Continental Divide from southern Canada south to northeastern Mexico (Baker et al.
1988; Hall 1981; Ramirez-Pulido and Castro Campillo 1994). Winter causes the range to
occur throughout the southeastern U.S. and northeastern Mexico with concentrations
highest in coastal Atlantic and Gulf of Mexico regions. Females generally occur in more
southern areas. Males tend to be more common in northern areas during winter. (Davis
and Lidicker 1955; LaVal and LaVal 1979; Padgett and Rose 1991).
Geographic Range
Lasiurus borealis is distributed throughout all of Wisconsin and from northern Mexico
and the eastern and central United States to southern Canada. Its range extends westward
to southwestern New Mexico, eastern Colorado, western North Dakota, and southwestern
Alberta.
It is also a native of the Bahamas, Cuba, Dominican Rep., Haiti, Jamaica, Mexico, Puerto
Rico, Trinidad/Tobago. (www.discoverlife.org, Linzey and Brecht 2002)),
(www.natureserve.org, Wilson and Reeder 1993, Reed 1997, Hall 1992). *Please see
geographical range maps, attachment “378 SA photos”)
Ontogeny & Reproduction
Observations suggest that the sexes migrate separately in the spring and occupy different
summer and winter ranges in some areas. Mothers frequently give birth to twins and
triplets. (www.batcon.org, Tuttle 2002)
With the exception of mothers and their offspring, red bats and other bats of the genus
Lasiurus generally roost solitarily. The mother in this picture is nursing quadruplets while
clinging to a grapevine. Unlike most other bats, red bats can have more than one pup.
(www.batcon.org, Tuttle 2002)
Eastern red bats usually mate in August and September, although the park mammal
collection contains two red bats in copulation that were taken on April 5. Females store
sperm in their reproductive tracts during the winter and ovulate in early spring. Following
a gestation period of 80-90 days, 1-5 young are born in June. The lasiurine bats,
particularly the red bat, are the only bats known that normally have 3 or 4 young per litter.
At birth the young weigh about 0.5 g each, and by 4 weeks of age they weigh nearly half
of the mother's weight. Between 3-6 weeks of age they can fly and are ready to be
weaned between 4-6 weeks of age. (www.discoverlife.org, Linzey and Brecht 2002)
Behavior & Ecology
The senses of sight and hearing are well developed in Lasiurus borealis, and bats in
general. Most bats become active near dusk and are active much of the night so sight is
of little importance in navigation and in the capture of prey. Via echolocation they emit
ultrasonic calls far above the range of human hearing that are reflected from objects
ahead of them. They hear the echoes and are able to avoid obstacles and find food in total
darkness. Different species can be distinguished by differences in the structure of their
echolocation calls (www.discoverlife.org and Fenton and Bell, 1981).
During feeding maneuvers, the tail and wing membranes are used to capture and restrain
prey. Some insects are captured by the tail membrane, which forms a pouch-like
compartment. The bat must bend its head forward in order to grasp the insect with its
teeth and take it into its mouth. Sometimes the bat may use its mouth to capture an insect
from its wing. Groups of several bats forage and interacts near street lights (Hickey and
Fenton, 1990), where they feed on an abundance of insects expecially Lepidoptera
(Acharya and Fenton, 1992) (www.discoverlife.org)
Lasiurus borealis have been found to eavesdrop on their conspecifics (Balcombe and
Fenton, 1998). This often leads to chases between bats (Hickey and Fenton, 1990), in
which low-frequency vocal interactions are common (M.K. Obrist, personal observation).
This suggests that lower-frequency bands are used in communication. Red bats use a
long, final, narrow-band component in sonar signals when foraging over long distances
(Obrist, 1995), but the dominant search-call frequency does not seem to be tuned in to
their outer ears. (Obrist et al 1993) (Obrist and Wenstrup 1997)
During colder times Red bats roost in the foliage of deciduous trees and are seldom found
far from forests. During the day they suspend by one foot and wrapped in their big furry
tails they look similar to dead leaves. They come together only to mate and migrate and
live solitary lives. One of the largest bat hibernacula in the Upper Midwest occurs at the
Neda Mine State Natural Area (WDNR, 1989), near the southern end of the Niagara
Escarpment in Wisconsin. The caves, sinkhole features, and excavations associated with
the former mine, provide summer roosting and winter hibernating sites for significant
numbers of bats. Other areas of the Escarpment, e.g., at Door County’s Peninsula State
Park, are also known to harbor bats but the regional and local significance of these sites is
unclear. (www.discoverlife.org)
Hibernation sites are usually tree hollows or under leaf litter. Unlike most other
hibernating bats, red bats often arouse and feed, even in January if temperatures rise
above 55 F. At such times, they can be seen feeding in bright sunlight as early as 2 or 3 in
the afternoon. During the coldest weather, red bats have the ability to raise their
metabolic rates enough to ensure a body temperature above their critical lower survival
limit of 23 F. When winter temperatures rise above 55 F they arouse and feed, often in
the brief warmth of mid-afternoon, in order to capture the few available insects.
(www.batcow.org, Tuttle 2002) (www.batcon.org, Tuttle 2002)
Habitat
Lasiurus borealis are often found along forest edges, edge habitats in general, or around
street lamps, where they hunt for insects, especially moths. Sometimes, they congregate
in large numbers around corncribs where they feed on grain moths associated with such.
Predators on red bats include several birds, especially blue jays. Lasiurus spp. are
commonly referred to as tree bats due to their general roosting in the foliage or trunks of
trees. (Griffin 1970) (www.batcon.org, Tuttle 2002)
Other Comments
The Spanish common name of Lasiurus borealis is “Un Murciélago”
(www.natureserve.org)
John Ragan of Troy, Michigan, has documented the first red bat to use a bat house. He
also attracted 245 little brown bats to seven of 12 houses on poles and a wooden building.
The red bat used just one location in the middle crevice of a medium-sized house painted
black and mounted on the building. The red bat stayed for one night only in July 1996
and again in July 1997. This solitary species normally roosts in tree foliage, and this is
the first observation of one from a crevice, much less a bat house. Ragan will report next
year if the red bat returns. Ragan’s other successes attracted the attention of several
raccoons, who preyed on about 10 to 15 bats in his pole-mounted houses. He thwarted
their efforts by installing metal predator guards around the base of each pole. The
raccoons did not give up easily, leaving claw marks in the metal, but were unable to
capture any more bats. (www.batcon.org Ragan)
In the submandibular gland of Lasiurus borealis “striated duct cells lack granules and
instead have an array of rod-like structures oriented perpendicular to the apical plasma
membrane to which they appear to be attached by very short filaments.” (Tandler and
Phillips, 2000)
References & Literature Cited
Acharya, L. and Fenton, M.B. (1992). “Echolocation behaviour of vespertilionid bats
(Lasiurus cinereus and Lasiurus borealis) attacking airborned targets including arctiid
moths. Can. J. Zool. (70): 1292-1298.
Bat Conservation of Wisconsin Inc. (BATCOW) in association w/ Merlin D. Tuttle
Information Available At: www.batcow.org, Last updated 14 Jan 2002.
Baker, R. J., J.C. Patton, H.H. Genoways, and J. W. Bickham (1988). Genic studies of
Lasiurus (Chiroptera: Vespertilionidae). Occasional Papers, The Museum, Texas Tech
University 117: 1-15.
Balcombe, J. and Fenton, M.B. (1998). Eavesdropping by bats: the influence of
echolocation call design and foraging strategies. Ethology 79: 158-166.
Bat Conservation International (BCI) in association w/ Merlin D. Tuttle
Information Available At: www.batcon.org
Carroll, Steven K., Timothy C. Carter, and George A. Feldhamer (2002). “Placement of
Nets for Bats: Effects on Perceived Fauna.” Southeastern Naturalist 1(2): 193-198.
Cryan, Paul M (2003). “Seasonal Distribution of Migratory Tree Bats (Lasiurus and
Lasionycteris) in North America.” Journal of Mammalogy 84(2): 579-593.
Davis, W.H., and W.Z. Lidicker, Jr. (1956). “Winter range of the red bat, Lasiurus
borealis. Journal of Mammalogy 37: 280-281.
Discoverlife Information, Available at: www.discoverlife.org
-Text by Dr. Donald W. Linzey, Wytheville Community Collegewclinzd@wcc.vccs.eud and Christy Brecht, Wytheville Community Collegewcbrecc@wcc.vccs.edu
-web page design and coding by Denise Lim and John Pickering, University of
Georgia, Athens, Last updated 08 Apr 2002
Fenton, M.B., and G.P. Bell. 1981. Recognition of insectivorous bats by their
echolocation calls. Journal of Mammalogy 62 (2): 233-243.
Griffin, D.R. (1970). “Migration and homing of bats. Pp. 233-264 in Biology of bats
(W.A. Wimsatt, ed.). Academic Press, New York.
Hall ER. 1982. The Mammals of North America, Volume 1 and 2. New York, John
Willey & Sons.
Mammalian Species, nos. 1-604. Published by the American Society of Mammalogists.
Hickey, M.B.C. and Fenton, M.B. (1990). Foraging by red bats (Lasiurus borealis): do
intraspecific chases mean territoriality? Can. J. Zool. 68: 2477-2482.
LaVal, R.K., and M.L. LaVal (1979). “Nothes on reproduction, behavior, and abundance
of the red bat, Lasiurus borealis. Journal of Mammalogy 60: 209-212.
Mager, Kenneth J. and Thomas A. Nelson (2000). “Roost-site Selection by Eastern Red
Bats (Lasiurus borealis)” The American Midland Naturalist 145(1): 120-126. Available
at: www.bioone.org/bioone/?request=getdocument&issn=0000031&volume=145&issue=01 &page=0120
Obrist, M.K., Fenton, M.B., Eger, J.L. and Schlegel, P.A. (1993). What ears do for bats:
a comparative study of pinna sound pressure transformation in Chiroptera. Journal of
Experimenta Biology 180: 119-152.
Obrist, M.K. (1995). “Flexible bat echolocation: the influence of individual, habitat and
conspecifics on sonar signal design. Behav. Ecol. Sociobiol 36: 207-219.
Obrist, Martin K., and Jeffrey J. Wenstrup (1998). “Hearing and Hunting in Red Bats
(Lasiurus borealis, Vespertillionidae): Audiogram and Ear Properties.” Journal of
Experimental Biology 201: 143-154.
Padgett, T.M., and R.K. Rose (1991). Bats (Chiroptera: Vespertilionidae) or the Great
Dismal Swamp of Virginia and North Carolina. Brimleyana 17: 17-25.
Ramirez-Pulido, J., and A. Castro-Campillo (1994). Bibliografía reciente de los
mamiferos de Mexico 1989-1993. Universidad Autonoma Metropolitana, Mexico City,
Mexico.
Reid, F. A. 1997. A field guide to the mammals of Central America and southern Mexico.
New York, Oxford Univ. Press.
Tandler, B, and Phillips, C.J (2000). “Organic Secretion by Striated Ducts.” European
Journal of Morphology 38 (4): 233-236.
Tuttle, Merlin D. (Spring 2000). “A Decade of Bat Conservation.” 10 (1): 3-10.
Available at: http://www.batcon.org/batsmag/v10n1-1.html, Last updated 1997
Wilson DE and Reeder DM. 1993. Mammal Species of the World, a Taxonomic and
Geographic Reference. Second Edition. Washington, Smithsonian Institution Press.
Wisconsin Department of Natural Resources (WDNR )
Information Available At:
www.dnr.state.wi.us/org/land/er/publications/niagara/Results.asp
Reference written by Nicole Woodward, Biology 378 student. Edited by Christopher Yahnke.
Page last updated.