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Nycteris thebaicaEgyptian slit-faced bat

By Lauren Esmailka

Geographic Range

Egyptian slit-faced bats are found throughout Africa and parts of southern Europe. They range from South Africa up through Egypt, the Arabian Peninsula, and to the island of Corfu. Nycteris thebaica is not found much outside of Africa and the Arabian Peninsula. (Corbet and Hill, 1991; Gray, et al., 1999; Nowak, 1999; Reeder and Wilson, 1993)

Habitat

This species is most often found in dry habitat types, such as savanna woodland areas. However, they are found in various other habitat types. (Gray, et al., 1999; Nowak, 1999)

These bats use a wide variety of roost sites, including caves, mine tunnels, tombs, military bunkers, masonary fireplaces, buildings, ruins, culverts, abandoned wells, pit latrines, root cavities, rock crevices, hollow trees, dense foliage, rocky outcrops, and sometimes the burrows of porcupines or aardvarks. Often times they separate roost sites for night and day. The selection of such a site is dependent on where they can find cool temperatures. (Gray, et al., 1999; Nowak, 1999)

  • Other Habitat Features
  • caves

Physical Description

Pelage tends to be long and silky, with a range of colors from gray, to light red, to murky brown, with a white to light grey stomach. Compared to other members of Nycteridae, this species has lighter pelage. Typically any animal that lives in dry habitats has a lighter pelage compared to those that live in wet habitats. (Gray, et al., 1999; Nowak, 1999)

This species varies greatly in body mass from 6.5 to 16 grams, and the total body length ranges from 83 to 168 mm, with a wingspan of 270 to 307 mm. Females tend to be larger than males. These bats have enormous ears that are longer than their total head length. Surprisingly, they have a very small tragus in relation to the size of their ears. An extensive nose leaf is also present, with a split in the middle. In proportion to their body size, they have a long tail, which is totally enclosed in a membrane called the uropatagium. The tip of the tail and uropatagium forms the shape of a "T", which is a distinctive characteristic of the family Nycteridae.

The dental formula for this species is I 2/3, C 1/1, P 1/2, M 3/3 = 32. Incisors are chisel-like in shape, and molars are small. Their P4 is so small it is almost not visible because it is hidden by P2 and M1. These bats are diphyodont, meaning there are two sets of teeth, one set of milk teeth, and another set of adult teeth. Nycteris thebaica is unique from other bats in that it retains its milk teeth outside of the womb. It is not uncommon for their milk teeth to be present for a short period of time with their first adult teeth. (Gray, et al., 1999; Nowak, 1999)

  • Sexual Dimorphism
  • female larger
  • Range mass
    6.5 to 16 g
    0.23 to 0.56 oz
  • Range length
    83 to 168 mm
    3.27 to 6.61 in
  • Range wingspan
    270 to 307 mm
    10.63 to 12.09 in

Reproduction

The mating systems of bats in the genus Nycteris have not been reported. (Nowak, 1999)

The reproductive cycles of females and males coincide, starting in March.

In populations in South Africa, females enter estrus in June. During this time breeding takes place. Gestation lasts between 2.4 to 6 months and takes place from June to November. Implantation of the fetus may not occur until as late as 16 days after mating. In tropical habitats, gestation is typically only 2.5 to 3 months. In more subtropical and temperate regions gestation usually lasts 5 months. This long period of gestation can be a result of the temperature or low resource availability. Females give birth during the month of November.

Lactation in related bats, Nycteris macrotis lasts for two months. It is likey that N. thebaica is similar.

The average body mass at birth is 6 g. (Gray, et al., 1999; Nowak, 1999)

  • Breeding interval
    In general, these bats breed once a year during the warmer months. However, many tropical populations have been known to have more than one breeding cycle.
  • Breeding season
    Populations in South Africa breed in May and June.
  • Range number of offspring
    1 (high)
  • Range gestation period
    2.5 to 6 months
  • Average weaning age
    2 months

The young when born are unable to fly. Neonates cling to their mother and travel with her while she goes on her daily quest for food starting in the early morning. This strategy is known to be a way of keeping the young clear of predators. At this stage the young weighs about half of the mother’s body mass.

Mothers provide the bulk of parental care in this species. The role of males in parental care has not been documented. (Gray, et al., 1999)

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

Lifespan/Longevity

There is little information about the lifespan and longevity of this species other than observations of those that have been kept in captivity.

Egyptian slit-faced bats do not do well in captivity. When given food and water they will eat the food, but will not touch the water, and as a result it is not uncommon for them to die of dehydration.

It is likely that individuals of this species live for many years, as most microchiropterans are long lived. (Gray, et al., 1999; Nowak, 1999)

Behavior

The majority of species in Nycteris live in either small groups or pairs. However, this species has been seen in colonies of as many as 500 to 600 individuals (with some reports estimating thousands of animals) in a single cave. Populations in South Africa have inhabited caves with other species of bats such as Myotis tricolor, Miniopterus schreibersii, Miniopterus fraterculus, Hipposideros caffer, Rhinolophus simulator, Rhinolophus clivosus, and Rhinolophus blasii. In Eastern Africa, these bats live in caves with Rousettus aegyptiacus and Taphozous perforatus. Mixed species groups of lactating females are known to roost in caves together, for example, in Egypt, N. thebaica, Asellia tridens, and Taphozous perforatus were all found together. (Gray, et al., 1999; Nowak, 1999)

These bats hang upside down from trees and other roosting sites. They attach themselves by their hind legs to the tree or cave with their heads positioned towards their backs.

This species is known to be migratory, but there is little information on the reasons for migration. It has been hypothesized that migration occurs as a result of resource availability. (Gray, et al., 1999)

Home Range

There is little available information about the home range of this species.

Communication and Perception

These bats, like most other bats, use echolocation for finding prey. However, like other gleaning bats, their echolocation calls are not strong and as a result this species is often called a “whispering” bat. The echolocation that they produce has low intensity, and is multi-harmonic. Echolocation is used when they are assessing the area around them, especially for prey location.

This species uses eyesight more than some bats, probably as compensation for its weak echolocation ability.

In addition to calls used for echolocation, researchers have identified two long tonal calls made by these bats. One is made in a roost and appears to attract other bats to the source of the call. The other call is made when bats leave the roost.

As in other mammals, tactile and chemical communication probably play some role in mating and parental care. (Gray, et al., 1999)

Food Habits

The diet of these bats is variable and dependent on geographic location and season.

This species eats a mixture of lepidopterans (butterflies and moths). They also feed on other insects and spiders. A major portion of their diet consists of scorpions when available. Other key components of their diet include: orthopterans and coleopterans. There are also numerous prey organisms that are only a minor part of their diet, such as: araneidans, dipterans, hemipterans, homopterans, hymenopterans, isopterans, and neuropterans. (Gray, et al., 1999; Nowak, 1999)

The feeding habits vary. Nycteris thebaica preys on organisms while flying, or observes them while hanging upside down from a tree and then goes after the prey. As these bats hang from a tree, they observe the surrounding area for prey. Their enormous ears are used to detect any noise made by potential prey. Once it hears a potential prey item, an individual bat will go after the area where the sound came from. In addition to their ears, they use their eyes (since echolocation is weak for these bats) to locate their prey.

This species also preys on insects that are not moving, such as on the ground, walls, rocks, lights, and vegetation. Small prey will be eaten on the spot, but larger prey will be taken to a tree and eaten while the bat is hanging. Their uropatagium is a tool that they use to bring their prey to their mouth. The females leave the roost at dusk (with their young) to go on regular hunts for food. (Gray, et al., 1999)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods

Predation

There is little available information on predation of this species. It is possible that they are prey to snakes as well as to some birds, including bat hawks, Machaerhamphus alcinus. Many members of the genus Nycteris asre reported to flutter around roosts, which could make them vulnerable to small mammals as well.

When the young are unable to fly, females take their young with them when they go hunting, as a way to avoid predators. (Gray, et al., 1999; Nowak, 1999)

Ecosystem Roles

As predators, these bats are likely to have some impact on insect populations. As prey, they may have a positive effect on their predators. In addition, N. thebaica is host for many parasites, including helminths, nematodes, trematodes, and standard mammalian ectoparasites. Mites infecting the margins of the ears are common in this species, and can cause individuals to damage their membranes from scratching. These bats may be an important reservoir host for nematode larvae in the suborder Spirurata, since these neoatodes use insects--the prey of the bats-- as intermediate hosts. (Gray, et al., 1999)

Commensal/Parasitic Species
  • helminths, nematodes, trematodes, and ectoparasites

Economic Importance for Humans: Positive

There is no known positive economic importance of this species for humans.

Economic Importance for Humans: Negative

There are no known adverse effects of this species on humans.

Conservation Status

There is little available information on the conservation status of N. thebaica. No information was found on either the IUCN Red List or CITES. These bats are not located in the United States and therefore are not found on the US Federal List.

Other Comments

There are no fossil specimens discovered of this species. (Nowak, 1999)

Contributors

Lauren Esmailka (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

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

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

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.

diurnal
  1. active during the day, 2. lasting for one day.
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

holarctic

a distribution that more or less circles the Arctic, so occurring in both the Nearctic and Palearctic biogeographic regions.

World Map

Found in northern North America and northern Europe or Asia.

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.

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.

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

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

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.

ultrasound

uses sound above the range of human hearing for either navigation or communication or both

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

Corbet, G., J. Hill. 1991. A World List of Mammalian Species. New York: Oxford University Press.

Gray, P., M. Fenton, V. Van Cakenberghe. 1999. "Index for Mammalian Species" (On-line pdf). Accessed November 10, 2004 at http://www.science.smith.edu/departments/Biology/VHAYSSEN/msi/.

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

Reeder, D., D. Wilson. 1993. Mammal Species of the World. Washington and London: Smithsonian Institution Press.

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