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.
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.
- Habitat Regions
- tropical
- terrestrial
- Terrestrial Biomes
- savanna or grassland
- chaparral
- forest
- rainforest
- scrub forest
- 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
.
- Other Physical Features
- endothermic
- homoiothermic
- bilateral symmetry
- Sexual Dimorphism
- male larger
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.
- Mating System
- polygynous
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
.
- Key Reproductive Features
- iteroparous
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- fertilization
- viviparous
- delayed implantation
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.
- Parental Investment
- altricial
-
pre-fertilization
- provisioning
-
protecting
- female
-
pre-hatching/birth
-
provisioning
- female
-
protecting
- female
-
provisioning
-
pre-weaning/fledging
-
provisioning
- female
-
protecting
- female
-
provisioning
-
pre-independence
-
provisioning
- female
-
provisioning
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.
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.
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.
- Key Behaviors
- arboreal
- troglophilic
- flies
- nocturnal
- crepuscular
- motile
- migratory
- daily torpor
- territorial
- colonial
Home Range
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.
- Perception Channels
- visual
- tactile
- acoustic
- echolocation
- chemical
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.
- Primary Diet
- carnivore
- 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.
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.
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.
- 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.
Additional Links
Contributors
Carl Roberts (author), University of Alaska Fairbanks, Link E. Olson (editor, instructor), University of Alaska Fairbanks.
Nancy Shefferly (editor), Animal Diversity Web.
- Ethiopian
-
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- tropical
-
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
- terrestrial
-
Living on the ground.
- 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.
- 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.
- forest
-
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
- 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.
- 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.
- 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.
- polygynous
-
having more than one female as a mate at one time
- 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).
- 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
- fertilization
-
union of egg and spermatozoan
- viviparous
-
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
- 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.
- 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.
- nocturnal
-
active during the night
- crepuscular
-
active at dawn and dusk
- motile
-
having the capacity to move from one place to another.
- migratory
-
makes seasonal movements between breeding and wintering grounds
- 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
- 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.
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- 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.
- chemical
-
uses smells or other chemicals to communicate
- carnivore
-
an animal that mainly eats meat
- insectivore
-
An animal that eats mainly insects or spiders.
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 :Â 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.