Animal Diversity Web

Ge­o­graphic Range

Bum­ble­bee bats (Craseonyc­teris thon­g­longyai) are found in the Ori­en­tal Re­gion of the world. They are found in Thai­land, in the Bi­lauk­taung moun­tain ranges in the west­ern part of the coun­try; Bum­ble­bee bats are mainly lo­cated in the Sai Yoke, Kan­chanaburi Province. They can also be found in the south east­ern parts of Myan­mar near the bor­der with Thai­land. (Humphery and Bain, 1990; Pear­son and Belet­sky, 2008)

• Biogeographic Regions
• oriental
  • native

Habi­tat

Bum­ble­bee bats pref­er­en­tially use lime­stone caves for roost­ing near the tops of the caves for warmth. Bam­boo forests serve for the habi­tat in which they find their food. Bum­ble­bee bats com­monly for­age in the upper canopy of the for­est. (Hill and Smith, 1981; Humphery and Bain, 1990)

• Habitat Regions
• tropical
• terrestrial

• Terrestrial Biomes
• rainforest

• Other Habitat Features
• caves

Phys­i­cal De­scrip­tion

Bum­ble­bee bats are about the size of a large bum­ble­bee, hence the com­mon name. These bats are con­sid­ered among one of the small­est mam­mals in the world. The size of the head and body is 29 to 33 mm long. The length of the bum­ble­bee bat fore­arms are 22 to 26 m, and adults weigh be­tween 1.7 and 2.0 g. It also has small eyes that are mostly hid­den by fur. Bum­ble­bee bats have 28 teeth, which in­cludes rel­a­tively large in­cisors. The lower in­cisors are long and nar­row. The upper body of bum­ble­bee bats can be 2 dif­fer­ent col­ors: brown­ish red, or gray. The un­der­side of the bat is a paler color while the wings and the mem­brane be­tween the legs, called the uropatag­ium, are darker. (Hill and Smith, 1981; Nowak, 1999)

Bum­ble­bee bats have a few dis­tinct char­ac­ters. First, bum­ble­bee bats do not have a tail even though they have two cau­dal ver­te­brae. Their uropatag­ium are rather large. Their noses are pig-like, with large nos­trils sep­a­rated by a wide sep­tum. Fi­nally they also have large ears that are 9 to 10.2 mm long. The tra­gus is around half the size of the ears. Fe­males have 2 sets of nip­ples, one on the chest and the other in the pubic area. The nip­ples in the pubic area are thought to be ves­ti­gial or not fully de­vel­oped. The males have a large swelling in the gland that is at the base of their throats. The wings of bum­ble­bee bats are long and wide, mak­ing them well adapted for hov­er­ing. They have thumbs that have claws. Their hind­foot is slen­der, nar­row, and long. Nowak (1999) de­scirbed bum­ble­bee bat skulls as small with a large in­flated spher­i­cal brain­case and lack­ing lamb­doidal crests, pos­tor­bital processes, and supraoc­cip­i­tal ridges. In both gen­ders a sagit­tal crest, which is a bone that runs down the top mid­dle of the skull, is vis­i­ble. The zy­go­mata, which is the arch in the cheek, is de­scribed as slen­der but com­plete (Nowak 1999). (Hill and Smith, 1981; Nowak, 1999)

• Other Physical Features
• endothermic
• bilateral symmetry

• Sexual Dimorphism
• sexes alike

• Range mass

  1.7 to 2.0 g

  0.06 to 0.07 oz

• Range length

  29 to 33 mm

  1.14 to 1.30 in

Re­pro­duc­tion

Lit­tle is known about the mat­ing sys­tems of bum­ble­bee bats. (Nowak, 1999)

Bum­ble­bee bats have one off­spring per year and breed once per year in late April to May. How­ever, lit­tle else is known about bum­ble­bee bat re­pro­duc­tion. (Hayssen, et al., 1993; Hus­ton, 2001; Nowak, 1999)

• Key Reproductive Features
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• viviparous

• Breeding interval

  Bumblebee bats breed once yearly.

• Breeding season

  Bumblebee bats breed in late April.

• Average number of offspring

  1

• Average time to independence

  1 years

While in­side the cave off­spring are usu­ally found at­tached to the mother. While the mother is for­ag­ing the off­spring is left alone. (Kurta and Kunz, 1987; Nowak, 1999)

• Parental Investment
• female parental care
• pre-weaning/fledging
  • protecting
    • female

Lifes­pan/Longevity

Bum­ble­bee bat lifes­pans are un­known but it is thought to be around 5 to 10 years based on the lifes­pans of other closely re­lated bats. (Ward, 2004)

Be­hav­ior

The be­hav­iors of bum­ble­bee bats are sim­i­lar to species within the fam­i­lies Mega­der­mati­dae, Rhinopo­mati­dae, Hip­posideri­dae, and Rhi­noolophi­dae. Bum­ble­bee bats are a motile species which are ca­pa­ble of long pow­ered flights. Bum­ble­bee bats are nor­mally ac­tive around dusk and dawn. The du­ra­tion of dawn ac­tiv­ity av­er­ages around 18 min­utes while at dusk the av­er­age time is 30 min­utes. When bats are not fly­ing they are thought to be in tor­por to con­serve en­ergy. Typ­i­cally, about 100 in­di­vid­u­als of this species will share the same cave. De­spite this con­gre­ga­tion, bum­ble­bee bats are not so­cial. Moth­ers will roost alone in the nurs­ery cave. (Bur­ton and Bur­ton, 2002; Humphery and Bain, 1990; Hus­ton, 2001; Nowak, 1999; Stenseth, 2000; Vaughn, et al., 2011)

• Key Behaviors
• troglophilic
• flies
• crepuscular
• motile
• daily torpor

Home Range

Bum­ble­bee bats only fly about 1 km from the cave to for­age. They do not main­tain or de­fend ter­ri­to­ries. (Hus­ton, 2001)

Com­mu­ni­ca­tion and Per­cep­tion

Bum­ble­bee bats use echolo­ca­tion to nav­i­gate their en­vi­ron­ment. They use sounds of a high in­ten­sity and have a con­stant fre­quency last­ing as long as 2 ms fol­lowed by a shal­low down­ward sweep last­ing a du­ra­tion of 1 ms. The be­gin­ning of the call has an up­ward sweep. The bats have a base fre­quency of 35 kHz. They also use two other har­mon­ics. The sec­ond one is at 70 kHz and the third one, which is weaker, is at 105 kHz. Noth­ing is known about how the bats com­mu­ni­cate within their roosts. (Hill and Smith, 1981; Surlykke, et al., 1993)

• Communication Channels
• acoustic

• Perception Channels
• tactile
• echolocation
• chemical

Food Habits

In­sects are bum­ble­bee bats main source of nu­tri­tion, but they also eat some spi­ders. They are aer­ial feed­ers, mean­ing they catch their prey while fly­ing. They pre­fer to fly and for­age along the tops of the bam­boo trees. (Humphery and Bain, 1990; Hus­ton, 2001; Ward, 2004)

• Primary Diet
• carnivore
  • insectivore

• Animal Foods
• insects
• terrestrial non-insect arthropods

Pre­da­tion

Cur­rently, noth­ing is known about the preda­tors of bum­ble­bee bats.

Ecosys­tem Roles

Due to small num­bers and small stature of bum­ble­bee bats, its ecosys­tem im­pact on its prey is prob­a­bly not sub­stan­tial. (Hus­ton, 2001)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

As in­sec­ti­vores bum­ble­bee bats may help with pest con­trol, but its im­pact is not con­sid­ered sub­stan­tial due to small pop­u­la­tion sizes. (Hus­ton, 2001)

• Positive Impacts
• controls pest population

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Bum­ble­bee bats have no known neg­a­tive ef­fects on hu­mans.

Con­ser­va­tion Sta­tus

Bum­ble­bee bats are con­sid­ered vul­ner­a­ble on the IUCN Red List and en­dan­gered on the U.S. En­dan­gered species list. The IUCN Redlist re­ports that the cur­rent pop­u­la­tion of 5100 in­di­vid­u­als is de­creas­ing. Ac­cord­ing to the IUCN Redlist, the species is dis­turbed by human ac­tiv­ity in caves. This ac­tiv­ity in­cludes habi­tat-al­ter­ing lime­stone ex­trac­tions. Their for­ag­ing habi­tats are also being de­for­ested, fur­ther de­creas­ing prey avail­abil­ity. (Humphery and Bain, 1990; Ward, 2004)

• IUCN Red List

  Vulnerable
  More information

• IUCN Red List

  Vulnerable
  More information

• US Federal List

  Endangered

• CITES

  No special status

• State of Michigan List

  No special status

Con­trib­u­tors

Alexan­dra Burns (au­thor), Rad­ford Uni­ver­sity, Karen Pow­ers (ed­i­tor), Rad­ford Uni­ver­sity, Kier­sten Newtoff (ed­i­tor), Rad­ford Uni­ver­sity, Melissa Whistle­man (ed­i­tor), Rad­ford Uni­ver­sity, Laura Podzikowski (ed­i­tor), Spe­cial Pro­jects.

Ref­er­ences

Brunet-Rossinni, A., S. Aus­tad. 2004. Age­ing stud­ies on bats: A re­view. Biogeron­tol­ogy, 5/1: 211-222.

Bur­ton, M., R. Bur­ton. 2002. The In­ter­na­tional Wildlife En­cy­clo­pe­dia: Vol­ume 3. Tar­ry­town, NY: Mar­shall Cavendish Cor­po­ra­tion.

Hayssen, V., A. Tien­hoven, A. Tien­hoven, S. As­dell. 1993. As­dell's Pat­terns of Mam­malian Re­pro­duc­tion: A Com­pendium of Species-spe­cific Data. Ithaca, NY: Com­stock Pub­lish­ing Com­pany.

Hill, J., S. Smith. 1981. Craseonyc­teris thon­g­longyai. Mam­malian Species, 160/1: 1-4.

Humphery, S., J. Bain. 1990. En­dan­gered An­i­mals of Thai­land. Gainsville, FL: Sand­hill Crane Press.

Hus­ton, A. 2001. Mi­crochi­ropteran Bats: Global Sta­tus Sur­vey and Con­ser­va­tion Ac­tion Plan. New­bury, UK: The Na­ture Con­ser­va­tion Bu­reau Ltd..

Kunz, T., M. Fen­ton. 2003. Bat Ecol­ogy. The Uni­ver­sity of Chicago: The Uni­ver­sity of Chicago Press.

Kurta, A., T. Kunz. 1987. Size of bats at birth and ma­ter­nal in­vest­ment dur­ing preg­nancy. Sym­posia of the Zo­o­log­i­cal So­ci­ety of Lon­don, 57/1: 79-106.

Mc­Cracken, G., G. Wilkin­son. 2000. Bat Mat­ing Sys­tems. Waltham, MA: Aca­d­e­mic Press.

Nowak, R. 1999. Walker's Mam­mals of the World Vol­ume 2. Bal­ti­more, MD: The Johns Hop­kins Uni­ver­sity Press.

Pear­son, D., L. Belet­sky. 2008. Thai­land. North­hamp­ton, MA: In­ter­link Pub­lish­ing Group.

Stenseth, N. 2000. Ac­tiv­ity Pat­terns in Small Mam­mals: An Eco­log­i­cal Ap­proach. Ger­many: Springer-Ver­lag Berlin Hei­del­berg.

Surlykke, A., L. Miller, B. Mohl, B. An­der­sen, J. Chris­tensen-Dals­gaard, M. Jer­gensen. 1993. Echolo­ca­tion in two very small bats from Thai­land: Craseonyc­teris thon­g­longyai and My­otis silig­oren­sis. Be­hav­ioral Ecol­ogy and So­ci­ol­ogy, 33/1: 1-12.

Vaughn, T., J. Ryan, N. Czaplewski. 2011. Mam­mol­ogy. Sud­bury, MA: Jones and Bartlett Pub­lish­ers.

Ward, A. 2004. Pocket Fact­files; En­dan­gered An­i­mals. Toronto, On­tario, Canada: An­drom­eda Ox­ford Lim­ited.