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Hipposideros commersoniCommerson's roundleaf bat

By Carl Roberts

Geographic Range

Giant leaf-nosed bats, also known as Commerson's leaf-nosed bats, are distributed throughout equatorial Africa and on the island of Madagascar. Recent studies have divided the species into 5 subspecies based on distinct regions of occurrence. Hipposideros commersoni commersoni is found only on the island of Madagascar. Hipposideros commersoni thomensis is located on the islands of Principe and Sao Tome. Hipposideros commersoni gigas is primarily located in western regions of equatorial Africa. Hipposideros commersoni niangarae is located only in the Niangara Region of the Congo. Hipposideros commersoni marungensis has the largest range and is found from East Africa to South Africa and Namibia. (Kingdon, 1984; Nowak, 1999)

Habitat

Commerson's leaf-nosed bats are known to prefer areas of edge habitat. Such areas provide perches along the corridors the bats use to travel. Large congregations occur in regions of dolomite because of the caves formed. In other regions smaller colonies are located in small caves and in hollow trees. (Vaughan, 1977)

  • Other Habitat Features
  • caves

Physical Description

Commerson's leaf-nosed bats are among the largest insectivorous members of the suborder Microchiroptera, ranging in weight from 40 to 180 g when mature. Lengths are reported at between 110 and 145 mm, and wingspans between 540 and 560 mm are recorded. Males are typically larger than females. Distinct skeletal characteristics of the species include a large sagital crest that is more prominent in males. Large canines and stout mandibles are other characters of the skull which are useful in identification. Pelage color ranges from a pale-grey to reddish-grey with tawny underparts. An elaborate nose leaf and falcate ears rounded near the tip distinguish H. commersoni. (Kingdon, 1984; Nowak, 1999)

  • Sexual Dimorphism
  • male larger
  • Range mass
    40 to 180 g
    1.41 to 6.34 oz
  • Average mass
    130 g
    4.58 oz
  • Range length
    110 to 145 mm
    4.33 to 5.71 in
  • Range wingspan
    540 to 560 mm
    21.26 to 22.05 in

Reproduction

Hipposideros commersoni males exhibit a form of resource defense polygyny, protecting access to areas of daylight roosts. Females apparently choose their mates based upon the quality of roosting areas they defend. (Cotterill and Fergusson, 1999)

Breeding in H. commersoni occurs once per year, and takes place between February and June. Females typically give birth to 1 pup after a gestation of around 4 months. The young are born at the start of the hot wet season when food availability is high. Weaning occurs around 14 weeks of age. Females may carry their young with them for about the first month of its life, as in Hipposideros fulvus, although data on H. commersoni are lacking on this facet of behavior. Other species of the genus Hipposideros are said to reach reproductive maturity around the age of 18 or 19 months, and H. commersoni is probably similar in this regard. In many species within the genus Hipposideros there is delayed implantation of the embryo after fertilization, and there may be variablilty in the length of development which is related to distance from the tropics. It is not known to what extent such characters are expressed in H. commersoni. (Nowak, 1999; Cotterill and Fergusson, 1999; Nowak, 1999)

  • Breeding interval
    Breeding occurs once annually.
  • Breeding season
    Copulation occurs near the end of the cool dry season (between February and June).
  • Average number of offspring
    1
  • Average gestation period
    4 months
  • Average weaning age
    14 weeks

Colonies of H. commersoni have been known to increase the humidity and temperature in the microclimate used for giving birth. This increased temperature is expected to provide more rapid development and reduce time until weaning. This is critical because the young must learn to forage before the end of the wet season during which food is plentiful. The nursing period is expected to be much shorter (approximately 14 weeks) than in other members of the genus, which nurse for about 5 months. Because of this accelerated schedule, the milk quality must be very high to allow for rapid skeletal growth. Because of the high cost of lactation to the female, she may enter torpor during the day to reduce her energetic costs. Males are not known to directly aid in care of the young. (Cotterill and Fergusson, 1999)

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

Lifespan/Longevity

No data for H. commersoni could be found, however, other members of the genus have been aged to at least twelve years old based on band recovery data. This species is probably similar in longevity to other members of the genus. (Nowak, 1999)

Behavior

Commerson's leaf-nosed bats are colonial bats often found in caves. Members of both sexes are known to enter torpor when unfavorable environmental conditions exist. This is most common during periods of low prey availability. When roosting, the bats are spaced slightly apart at a wing-tip distance. This slight territorality is found in both sexes. When roosting and disturbed, a shrill audible alarm call is made. Females have two annual migrations within the region which are likely caused by interspecific competition for food during periods of high nutritional demand. (Cotterill and Fergusson, 1999; Kingdon, 1984)

In general, members of the genus Hipposiderus are known to roost in trees, buildings, and caves. These animals are nocturnal, and, like all bats, are able to fly. Hipposideros is known to fly lower than most bats, catching insects, such as beetles and cicadas, using the sounds made by the prey animals to locate them. Members of this genus do use echolocation in catching prey also, and seem to be somewhat specialized to short-range hunting with calls emitted from the nostrils. (Nowak, 1999)

Home Range

Home range size for this species has not been reported. (Nowak, 1999)

Communication and Perception

Communication in this species has not been fully described. Members of the genus Hipposideros are known to have some vocalizations. They echolocate to capture prey in addition to using the noises made by the prey themselves. It is likely that tactile communication occurs within the roost, between offspring and the mother, and between mates. Olfaction is typically important in mammals, and may play some role in identifying individuals or reproductive conditions in this species. Although these bats have eyes, most microchiropterans are not known for their well developed visual abilities. (Nowak, 1999)

Food Habits

Commerson's leaf-nosed bats use their powerful jaws and sharp canines to catch and consume large beetles. The bats have evolved two different strategies to capture prey: Sedentary observation and collection, and hunting actively during flight. The sedentary perching involves flying to a known roost and scan the area. When prey is observed, the bat flies from the perch to collect it, then returns to the roost to consume the prey item. The second strategy involves actively searching for the prey by flying at a level of about 2 meters actively echolocating for prey on the ground. (Vaughan, 1977)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods

Predation

Bat hawks are reported to be predatory on these bats. It is likey that other small mammals and snakes may prey on this species as well. Vulnerability to predation is often highest for bats as these animals emerge from roosting sites. (Nowak, 1999; Vaughan, 1977)

  • Known Predators
    • Bat Hawk Machaerhamphus alcinus

Ecosystem Roles

Because H. commersoni feeds primarily on beetles and has very few natural predators, we can speculate that this species is near top of of the food chain but does not occupy the keystone species niche in its woodland habitat. Commerson's leaf-nosed bats might have a slightly larger ecological role in the cave ecosystem, into which the bats bring large amounts of nitrogen. (Vaughan, 1977)

Economic Importance for Humans: Positive

Roosting caves of H. commersoni in some regions of equatorial Africa have very high densities of bats, and have been inhabited by these animals for many, many years. The feces, or guano, from the bats is important commercially in these areas as a source of nitrogen for fertilizers. (Cotterill and Fergusson, 1999)

  • Positive Impacts
  • produces fertilizer

Economic Importance for Humans: Negative

There are no known adverse affects of H. commersoni on humans

Conservation Status

The conservation status of these animals remains unknown. Although over 34 members of the genus Hipposideros are listed as endangered, vulnerable, or threatened by various agencies, H. commersoni is not listed by CITES or IUCN. (Nowak, 1999)

Contributors

Carl Roberts (author), University of Alaska Fairbanks, Link E. Olson (editor, instructor), University of Alaska Fairbanks.

Nancy Shefferly (editor), Animal Diversity Web.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chaparral

Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.

chemical

uses smells or other chemicals to communicate

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

crepuscular

active at dawn and dusk

delayed implantation

in mammals, a condition in which a fertilized egg reaches the uterus but delays its implantation in the uterine lining, sometimes for several months.

echolocation

The process by which an animal locates itself with respect to other animals and objects by emitting sound waves and sensing the pattern of the reflected sound waves.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

migratory

makes seasonal movements between breeding and wintering grounds

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

polygynous

having more than one female as a mate at one time

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Cotterill, F., R. Fergusson. 1999. Reproductive ecology of Commerson's leaf-nosed bats Hipposideros commersoni (Chiroptera: Hipposideridae) in South-Cental Africa: interactions between seasonality and large body sizes; and implications for conservation. South African Journal of Zoology, 34/1: 53-63.

Kingdon, J. 1984. East African mammals : an atlas of evolution in Africa. Chicago: The University of Chicago Press.

Nowak, R. 1999. Walker's Mammals of the World, Sixth Edition. Baltimore and London: The Johns Hopkins University Press.

Vaughan, T. 1977. Foraging Behavior of the giant leaf-nosed bat (Hipposideros commersoni). East African Journal of Wildlife, 15: 237-249.

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