Animal Diversity Web

Ge­o­graphic Range

La­si­u­rus bo­re­alis, or red bats, are widely dis­trib­uted in forested re­gions, oc­cur­ring from south­ern Canada through Cen­tral Amer­ica and into Chile and Ar­gentina. Red bats mi­grate to warmer re­gions dur­ing win­ter.

• Biogeographic Regions
• nearctic
  • native
• neotropical
  • native

Habi­tat

La­si­u­rus bo­re­alis are fast fly­ing bats that live through­out the Amer­i­cas. They tend to choose habi­tats that are sparsely to mod­er­ately pop­u­lated by hu­mans and are rare in heav­ily ur­ban­ized areas.

• Habitat Regions
• temperate
• tropical

• Terrestrial Biomes
• forest

Phys­i­cal De­scrip­tion

Red bats are medium sized bats hav­ing a total length of 93 to 117 mm. Body length is ap­prox­i­mately 40 to 50 mm and weight ranges be­tween 7 to 13 g. The hind­foot length is 6 to 11 mm. Height of the ear from the notch is 8 to 13 mm. Length of the fore­arm varies be­tween 36 and 46 mm.

Pelage varies in color from a brick red to a yel­low­ish red. The fur is white at the tips giv­ing these bats a frosted ap­pear­ance. In gen­eral, fe­male bats ap­pear more frosted com­pared to males, and males have a red­der color than fe­males. There is no doc­u­mented sex­ual di­mor­phism in size. The uropatag­ium is thickly furred on the dor­sal side and helps to keep these bats warm in cold weather.

La­si­u­rus bo­re­alis have small and heav­ily con­structed skulls. The arrange­ment of the 32 teeth is dis­tinc­tive and shared with other La­si­u­rus species. Red bats have a tiny cone shaped upper pre­mo­lar that is lo­cated at the inner junc­tion of the upper ca­nine and the sec­ond pre­mo­lar.

Red bats have been called by Allen Kurta, au­thor of "Mam­mals of the Great Lakes," one of the "most hand­some mam­mals in the Great Lakes re­gion."

• Other Physical Features
• endothermic
• bilateral symmetry

• Sexual Dimorphism
• sexes colored or patterned differently

• Range mass

  7 to 13 g

  0.25 to 0.46 oz

• Range length

  93 to 117 mm

  3.66 to 4.61 in

Re­pro­duc­tion

An in­com­plete ac­count of a red bat mat­ing in flight was made in 1947. A bat bi­ol­o­gist was fly fish­ing and watched as he saw what looked like a sin­gle bat tum­ble onto the bank. The bi­ol­o­gist in­spected with his flash­light, and saw what he orig­i­nally thought was a fe­male bat with young cling­ing to her. Under closer in­spec­tion the bi­ol­o­gist saw that a male had clasped it­self to the back of the fe­male there­fore mak­ing it im­pos­si­ble for ei­ther to fly. It seemed as if the male red bat had at­tached it­self to the fe­male in mid-flight. The male bat seemed to hold his po­si­tion by hook­ing his claw over the fe­male's wing.

Mat­ing takes place in flight and cop­u­la­tion usu­ally oc­curs in Au­gust or Sep­tem­ber. The sperm is stored until the spring, usu­ally March or April. Fe­male red bats pos­sess four mam­mary glands while most other chi­ropter­ans have two. Fe­male red bats give birth to one lit­ter of twins each year, un­like most bats which give birth to sin­gle young. New­born bats are hair­less and weigh ap­prox­i­mately 1.5 g. The young learn to fly at about five weeks old.

• Key Reproductive Features
• iteroparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• viviparous
• sperm-storing
• delayed fertilization

• Breeding interval

  Red bats breed once each year.

• Breeding season

  Mating occurs in August or September.

• Range number of offspring

  1 to 4

• Average number of offspring

  2

• Range gestation period

  80 to 90 days

• Average weaning age

  38 days

• Average time to independence

  5 weeks

Like all mam­mals, fe­male red bats nurse their young until the young are able to fend for them­selves. It takes young red bats about five weeks to learn how to fly and for­age on their own.

• Parental Investment
• pre-fertilization
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • provisioning
    • female
  • protecting
    • female

Be­hav­ior

Red bats are mi­gra­tory, ar­riv­ing in the north­ern cli­mates in mid-April and leav­ing in late Oc­to­ber. There are records of bats hi­ber­nat­ing in the north­ern parts of their range, but they typ­i­cally mi­grate to warmer re­gions. When red bats hi­ber­nate they choose hol­low trees. They main­tain body tem­per­a­tures just above freez­ing and can­not with­stand pro­longed pe­ri­ods of below freez­ing tem­per­a­tures. They may lose up to 25% of their pre-hi­ber­na­tion weight by spring, se­verely de­plet­ing fat re­serves (Fen­ton, 1985).

La­si­u­rus bo­re­alis choose roost­ing sites in dense fo­liage. They may be vis­i­ble hang­ing from branches or leaves but their col­oration helps to cam­ou­flage them from preda­tors. Their red coat is par­tic­u­larly help­ful at cam­ou­flag­ing them in sycamore, oaks, elm, and box elder trees and they seem to pre­fer these trees as roost sites (Con­stan­tine, 1996). Sites that have been used as roost­ing areas range from 2 to 40 feet off the ground. The roost­ing sites of soli­tary bats have not been as well stud­ied as those of more gre­gar­i­ous bats. Some field work­ers be­lieve that red bats de­fend feed­ing ter­ri­to­ries. (Con­stan­tine, 1966; Fen­ton, 1985)

• Key Behaviors
• flies
• nocturnal
• motile
• migratory
• hibernation
• solitary

Com­mu­ni­ca­tion and Per­cep­tion

Red bats use echolo­ca­tion to lo­cate prey. They use both broad­band and nar­row band calls. Search phases of calls use long calls with low pulse rep­e­ti­tion of nar­row band fre­quen­cies.

• Perception Channels
• tactile
• acoustic
• echolocation
• chemical

Food Habits

Red bats are in­sec­tiv­o­rous. They cap­ture in­sects while fly­ing like many other in­sec­tiv­o­rous bats.

Red bats have been found in in­sect light traps. The ac­tiv­ity of these bats around lights re­flects over­all flight and feed­ing pat­terns. Hunt­ing for food be­gins at dusk and the bat pro­ceeds to hunt within 500 m of a light source (Hickey et al 1996). For­ag­ing ac­tivies of this bat are gen­er­ally con­cen­trated into one feed­ing bout, but there are records of these bats for­ag­ing through­out the night. Their food con­sists of dif­fer­ent kinds of in­sects: moths, bee­tles, plant-hop­pers, ants, flies, and oth­ers.

Red bats make one pass through a con­cen­tra­tion of po­ten­tial prey, fix­ing on a tar­get within 5 to 10 m. They at­tack in­sects, on av­er­age, every thirty sec­onds and are suc­cess­ful fourty per­cent of the time. If a bat is stalk­ing a moth using echolo­ca­tion the moth can hear this and will try to flee the at­tack by div­ing. The bat will fol­low the moth into a steep dive and often will pull away within inches of the ground. Hu­mans ob­serv­ing this preda­tor-prey in­ter­ac­tion only see the bat and not the flee­ing moth and may be­lieve that the bat is act­ing ag­gres­sively to­wards them.

There is a dis­tinct body and head pos­tur­ing change in this bat when in pur­suit of prey. It has been said that if you ob­serve a rural street light and see a bat dip­ping and div­ing, that you are most likely view­ing a red bat. (Hickey, et al., May 1996)

• Primary Diet
• carnivore
  • insectivore

• Animal Foods
• insects

Pre­da­tion

Preda­tors of red bats in­clude birds of prey and opos­sums. Hu­mans and human con­struc­tions have also taken their toll on red bats. "There have been doc­u­mented cases of these bats being im­paled by barbed wire, . . . en­trapped on road sur­face oil . . ., fly­ing into light­houses . . ., and ra­di­a­tor grills of au­to­mo­biles . . ." (Baker, 1983, pg. 123).

Red bats avoid preda­tors through the use of cam­ou­flage. (Baker, 1983)

• Anti-predator Adaptations
• cryptic

• Known Predators

  • birds of prey
  • opossums
  • birds of prey (Falconiformes)
  • opossums (Didelphis virginiana)

Ecosys­tem Roles

Red bats play an im­por­tant ecosys­tem role as in­sect con­sumers.

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Red bats rarely in­vade homes. Red bats keep in­sect pop­u­la­tions down.

• Positive Impacts
• controls pest population

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Un­for­tu­nately some peo­ple view red bats, along with all other bats, as ver­min. How­ever, red bats do not neg­a­tively af­fect hu­mans.

Con­ser­va­tion Sta­tus

Red bats are se­cure over most of their range and are not con­sid­ered threat­ened.

Tem­per­ate North Amer­i­can bats are now threat­ened by a fun­gal dis­ease called “white-nose syn­drome.” This dis­ease has dev­as­tated east­ern North Amer­i­can bat pop­u­la­tions at hi­ber­na­tion sites since 2007. The fun­gus, Ge­omyces de­struc­tans, grows best in cold, humid con­di­tions that are typ­i­cal of many bat hi­ber­nac­ula. The fun­gus grows on, and in some cases in­vades, the bod­ies of hi­ber­nat­ing bats and seems to re­sult in dis­tur­bance from hi­ber­na­tion, caus­ing a de­bil­i­tat­ing loss of im­por­tant meta­bolic re­sources and mass deaths. Mor­tal­ity rates at some hi­ber­na­tion sites have been as high as 90%. While there are cur­rently no re­ports of La­si­u­rus bo­re­alis mor­tal­i­ties as a re­sult of white-nose syn­drome, the dis­ease con­tin­ues to ex­pand its range in North Amer­ica. (Cryan, 2010; Na­tional Park Ser­vice, Wildlife Health Cen­ter, 2010)

• IUCN Red List

  Least Concern
  More information

• IUCN Red List

  Least Concern
  More information

• US Federal List

  No special status

• CITES

  No special status

• State of Michigan List

  No special status

Con­trib­u­tors

Al­li­son Poor (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor.

Phil Myers (au­thor), Mu­seum of Zo­ol­ogy, Uni­ver­sity of Michi­gan-Ann Arbor, Jani Hatch­ett (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor, Phil Myers (ed­i­tor), Mu­seum of Zo­ol­ogy, Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

Al­tring­ham, J. 1996. Bats bi­ol­ogy and be­hav­iour. Ox­ford: Ox­ford Uni­ver­sity Press.

Baker, `. 1983. Michi­gan Mam­mals. Lans­ing: Michi­gan State Uni­ver­sity Press.

Con­stan­tine, D. 1966. Eco­log­i­cal ob­ser­va­tion of la­si­urine bats in Iowa. Jour­nal of Mam­mal­ogy, 47: 34-41.

Cryan, P. 2010. "White-nose syn­drome threat­ens the sur­vival of hi­ber­nat­ing bats in North Amer­ica" (On-line). U.S. Ge­o­log­i­cal Sur­vey, Fort Collins Sci­ence Cen­ter. Ac­cessed Sep­tem­ber 16, 2010 at http://​www.​fort.​usgs.​gov/​WNS/​.

Davis, W., W. Lidicker. May 1956. Win­ter range of the red bat, La­si­u­rus bo­re­alis. Jour­nal of Mam­mal­ogy, 37: 280-281.

Fen­ton, B. 1985. Com­mu­ni­ca­tion in the Chi­roptera. Bloom­ing­ton: In­di­ana Uni­ver­sity Press.

Fen­ton, B. 1983. Just Bats. Toronto: Uni­ver­sity of Toronto Press.

Hickey, B., L. Acharya, S. Pen­ning­ton. May 1996. Re­source par­ti­tion­ing by two species of ves­per­til­io­nis bats (Laiu­rus cinereus and La­si­u­rus bo­re­alis) feed­ing around street light. Jour­nal of Mam­mol­ogy, 77: 325-334.

Hickey, B., A. Neil­son. 1995. Rel­a­tive ac­tiv­ity and oc­curence of bats in South­westen On­tario as de­ter­mined by mon­i­tor­ing with bat de­tec­tors. The Cana­dia Field-Nat­u­ral­ist, 109: 413-417.

Na­tional Park Ser­vice, Wildlife Health Cen­ter, 2010. "White-nose syn­drome" (On-line). Na­tional Park Ser­vice, Wildlife Health. Ac­cessed Sep­tem­ber 16, 2010 at http://​www.​nature.​nps.​gov/​biology/​wildlifehealth/​White_​Nose_​Syndrome.​cfm.

Per­ston, R. 1964. Silently, By Night. New York: Mc­Graw and Hill.

Schober, W., E. Grimm­berger. 1997. The bats of Eu­rope and North Amer­ica. Dal­las: T.F.H. Pub­li­caitons, Inc. 1997.

Slaugh­ter, B., D. Wal­ton. 1970. About Bats a Chi­ropteran bi­ol­ogy syn­po­sium. Dal­las: South­west­ern Methodist Uni­ver­sity Press.

Stuewer, F. 1948. A record of red bats mat­ing. Jour­nal of Mam­mal­ogy, 29 (2): 180-181.

Wil­son, N. 1965. Red bats at­tracted to in­sect light traps. Jour­nal of Mam­mal­ogy, 46 (4): 704-705.