Mauritian Tomb Bat
Encyclopedia
The Mauritian Tomb Bat (Taphozous mauritianus) is a species of sac-winged bat
Sac-winged bat
The 51 species of sac-winged or sheath-tailed bats constitute the family Emballonuridae, and can be found in tropical and subtropical regions all over the world. Emballonurids include some of the smallest of all bats, and range from 3.5 to 10 cm in body length...

 in the family Emballonuridae that is found in central and southern Africa and Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...

. It was discovered in 1818 by Étienne Geoffroy Saint-Hilaire
Étienne Geoffroy Saint-Hilaire
Étienne Geoffroy Saint-Hilaire was a French naturalist who established the principle of "unity of composition". He was a colleague of Jean-Baptiste Lamarck and expanded and defended Lamarck's evolutionary theories...

, and is characterized by an all-white ventral surface, grizzled dorsal coloration, and conical face. It has exceptionally good eyesight, a trait which common is old world bats and enables it to find roosting locations. It has adapted itself to a wide-range of habitats including subarid scrub
Shrubland
Shrubland, scrubland, scrub or brush is a plant community characterized by vegetation dominated by shrubs, often also including grasses, herbs, and geophytes. Shrubland may either occur naturally or be the result of human activity...

 to semi-tropical savanna
Savanna
A savanna, or savannah, is a grassland ecosystem characterized by the trees being sufficiently small or widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of C4 grasses.Some...

 and can be found throughout much of Africa south of the Sahara, including many of the surrounding islands. Mauritian tomb bats help control pest populations, including insects that carry human diseases. These bats tend to be nocturnal hunters and their normal prey consists of moths, butterflies, and termites. Not prone to large scale roosting, T. mauritianus is most often spotted on the sides of buildings or on the trunks of trees in groups of around five individuals. They breed one average once or twice a year and rear usually one pup, though twins are occasionally reported. This species is listed as least concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...

 on the IUCN Red List due their wide distribution and stable population.

Taxonomy and etymology

The French naturalist Étienne Geoffroy Saint-Hilaire
Étienne Geoffroy Saint-Hilaire
Étienne Geoffroy Saint-Hilaire was a French naturalist who established the principle of "unity of composition". He was a colleague of Jean-Baptiste Lamarck and expanded and defended Lamarck's evolutionary theories...

 identified the Mauritian tomb bat in 1818 when he compared the at the time unknown specimen to another newly described bat from Egypt, the Egyptian Tomb Bat
Egyptian Tomb Bat
The Egyptian Tomb Bat is a species of sac-winged bat in the family Emballonuridae.It is found in Benin, Botswana, Burkina Faso, Democratic Republic of the Congo, Djibouti, Egypt, Ethiopia, Gambia, Ghana, Guinea-Bissau, India, Iran, Kenya, Mali, Mauritania, Niger, Nigeria, Pakistan, Saudi Arabia,...

. The Egyptian tomb bat (T. perforatus) is the same size as its Mauritian cousin but does not have the completely white belly that the latter possess.

The name "tomb" bat and the genus name Taphozous is derived from the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 word for a tomb or grave. Mauritianus simply means "of Mauritius," where it was first discovered. Though the name would suggest a dark, closed-in habitat, the Mauritian tomb bat lives in a variety of environments and is not restricted tombs or caves. The term "tomb bat" was given because the genus is commonly seen on the walls of old tombs in their respective ranges.

Synonyms for the Mauritian tomb bat include Taphozous mauritianus, T. leucopterus, T. dobsoni, and T. maritianus var. vinerascens. The Afrikaans
Afrikaans
Afrikaans is a West Germanic language, spoken natively in South Africa and Namibia. It is a daughter language of Dutch, originating in its 17th century dialects, collectively referred to as Cape Dutch .Afrikaans is a daughter language of Dutch; see , , , , , .Afrikaans was historically called Cape...

 word for this species is witlyfvlermuis, which refers to the white ventral surface that is characteristic of the species. Other species of the genus include the Coastal Tomb Bat
Coastal Tomb Bat
The Coastal Sheath-tailed Bat or Coastal Tomb Bat, Taphozous australis, is a species of sheath-tailed bat in the family Emballonuridae.It is found in Australia and Papua New Guinea.-References:...

, Hildegarde's Tomb Bat
Hildegarde's Tomb Bat
Hildegarde's Tomb Bat is a species of sac-winged bat in the family Emballonuridae.It is found in Kenya and Tanzania.Its natural habitats are subtropical or tropical dry forests and caves....

, Black-bearded Tomb Bat
Black-bearded Tomb Bat
The Black-bearded Tomb Bat is a species of sac-winged bat in the family Emballonuridae.It is found in Bangladesh, Cambodia, China, India, Indonesia, Laos, Malaysia, Myanmar, Sri Lanka, Thailand, Timor-Leste, Vietnam, and possibly the Philippines.-References:* Chiroptera Specialist Group 1996....

, and several others (For more species, see taphozous
Taphozous
Taphozous is a genus of sac-winged bat in the family Emballonuridae.It contains the following species:* Indonesian Tomb Bat * Coastal Tomb Bat * Sharp-Nosed Tomb Bat...

).

Description

The Mauritian Tomb Bat is distinguished from other species of bat by a completely white ventral area. The dorsal surface of T. mauritianus is a mottled color consisting of several shades of brown, gray, and white, which creates a grizzled "salt and pepper" appearance. Its fur is sleek and short, and the wing membranes are beige and primarily translucent. The wings are long, narrow, and shorten when not in flight in a way that facilitates crawling, a trait unique to this genus. Sexes are similar in color and size. Adults are generally lighter in color than juveniles
Juveniles
Juvenile may refer to:* Juvenile * Minor * Children's literature* Children's clothing...

, who have more of a gray hue. This species has a conically shaped face, which is covered in a thin layer of hair. The area below and in front of the eyes is bare, and the frontal portion of the face is sunken around the eyes. The eyes are large (2–3 mm). The ears are triangular-shaped, erect, and have rounded edges. The inner margins of the ear lack papillae, which is the inner sensory surface of the bat's ear. One of the larger species in the Microchiroptera suborder, fully grown adults weigh anywhere from 25 to 36 grams, with its forearm measuring 58 to 64 millimeters. The total length is from 100 to 110 millimeters.

Sexual dimorphism

T. mauritianus does not display an abundance of visual sexual dimorphism
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...

 concerning their size or coloration. Outside of the breeding season, the male reproductive organs are held in the abdominal cavity. During the breeding season, the genitals appear and become darker in color. The males possess a gular sac that lies at the base of the jaw. This gland releases secretions that help males mark their territories and attract females during the mating season. The gular sac is present in some females, depending on which region Africa the bat is found. In areas such as Nigeria
Nigeria
Nigeria , officially the Federal Republic of Nigeria, is a federal constitutional republic comprising 36 states and its Federal Capital Territory, Abuja. The country is located in West Africa and shares land borders with the Republic of Benin in the west, Chad and Cameroon in the east, and Niger in...

 and Mozambique
Mozambique
Mozambique, officially the Republic of Mozambique , is a country in southeastern Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi and Zambia to the northwest, Zimbabwe to the west and Swaziland and South Africa to the southwest...

, the sac is absent in females, in West Africa it is reduced to a vestigial pouch, and in the Sudan
Sudan
Sudan , officially the Republic of the Sudan , is a country in North Africa, sometimes considered part of the Middle East politically. It is bordered by Egypt to the north, the Red Sea to the northeast, Eritrea and Ethiopia to the east, South Sudan to the south, the Central African Republic to the...

 it is fully present in both sexes, just more developed in males. In females, the genitals are located on the ventral side of the abdomen and are marked by two pigmented patches. During the mating season, they become deeply pigmented and extend out, becoming more prominent before and just after mating.

Distribution and habitat

The Mauritian tomb bat is widely distributed from the middle to the southern regions of Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

, as well as on many of the surrounding islands. They are found in Angola, Benin, Botswana, Central African Republic, Chad, Republic of the Congo, Democratic Republic of the Congo, Ivory Coast, Equatorial Guinea, Ethiopia, Gabon, Gambia, Ghana, Kenya, Madagascar, Malawi, Mauritius, Mozambique, Namibia, Nigeria, Réunion, São Tomé and Príncipe, Senegal, Seychelles, Sierra Leone, Somalia, South Africa, Sudan, Swaziland, Tanzania, Togo, Uganda, Zambia, and Zimbabwe. Some Mauritian tomb bats have been found on Bourbon.

Special kidney
Kidney
The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...

 adaptations that aid in water conservation allow the Mauritian tomb bat to survive in the often dry, semi-arid
Semi-arid
A semi-arid climate or steppe climate describes climatic regions that receive precipitation below potential evapotranspiration, but not extremely...

 regions of countries such as the Sudan and Chad. The bat's kidneys have a mean renal index
Urinary index
The urinary indices are the fractional sodium excretion index and the renal failure index .The renal failure index = Urine Sodium * Plasma Creatinine / Urine Creatinine....

 of 5.55. This means that the bat's inner medulla
Medulla
Medulla refers to the middle of something and derives from the Latin word for marrow. Its anatomical uses include:* Medulla oblongata, a part of the brain stem* Renal medulla, a part of the kidney* Adrenal medulla, a part of the adrenal gland...

, the part of the kidney that collects waste, is very large compared to the overall size of the organ, so that the animal can remove much of the waste out the water it drinks. The bats have a predicted mean maximum urine concentration of 3,921 mosmol/kg, which means the urine they produce is very concentrated. From this, scientists have tentatively come to the conclusion that this species' kidneys offer valuable water conservation
Water conservation
Water conservation refers to reducing the usage of water and recycling of waste water for different purposes such as cleaning, manufacturing, and agricultural irrigation.- Water conservation :Water conservation can be defined as:...

.

Mauritian tomb bats are occasionally found in grassland
Grassland
Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...

 biomes as well as in semi-arid and tropical regions. They can be found in forests, rain forests, and grasslands. These bats can be found in the Sahara
Sahara
The Sahara is the world's second largest desert, after Antarctica. At over , it covers most of Northern Africa, making it almost as large as Europe or the United States. The Sahara stretches from the Red Sea, including parts of the Mediterranean coasts, to the outskirts of the Atlantic Ocean...

, which receives less than 500 mm of rainfall per year. The bats prefer open, moist savanna with plenty of maneuvering room with close proximity roosting sights. Often this species can be found near open swamps and rivers, where there is a steady food supply. They may need the open water for hunting. T. mauritianus avoids the thicker parts of tropical forests due to its somewhat limited turning maneuverability. In some countries, such as Sao Tomé and Principe, groups of this species find homes in the cocoa trees of the large plantations, which offer an excellent environment with roosts, adequately spaced trees, and many insects to feed upon.

The tomb bat prefers sites where there is overhead shelter, but are situated in exposed positions for easier take off. T. mauritianus's natural roosting locations include the trunks of palm trees, caves, and crevices. With the arrival of humans, they have adapted to a variety of new locations such as the sides of buildings and, as their name implies, tombs. They prefer buildings with bare brick surfaces as opposed to painted ones, as it offers better grip. They choose their day roosts so that take-off is unhindered by obstacles inhibiting flight.

Behavior and ecology

The Mauritian tomb bat is often found in groups of around five individuals. These groups are usually either made up of entirely male or female individuals; when they are found in mixed gender groups, the two sexes are separated by at least 100 mm. Females live together in groups of three to thirty, while males live alone except during the mating season. Unlike some species of bats, they do not roost close together in tight packs; instead they are found spaced out loosely, with the exception of a mother and her offspring. There are places where groups of at least a hundred bats have been found, one example being the Shai Hills Resource Reserve in Ghana
Ghana
Ghana , officially the Republic of Ghana, is a country located in West Africa. It is bordered by Côte d'Ivoire to the west, Burkina Faso to the north, Togo to the east, and the Gulf of Guinea to the south...

.

They usually roost with their ventral side flat against a surface. The Mauritian tomb bat is nocturnal and rests during the day; however, it does not sleep much and remains watchful while roosting. If disturbed, they will fly off to another site or move quickly up under the eaves of the building. Very rarely do they travel far from their day roosting site, and roosts are often recolonized. Over time these sites become stained with gular sack secretions and urine. The stains are typically a rectangular brown shape roughly 150 mm long and 100 mm wide.

The semi-diurnal activity of tomb bats has led to the evolution of relatively good eyesight, unlike most echolocating bats. Their vision is very similar to the eyesight found in that of Old-World bats. The presence of the dim-light (RH1) gene in both the tomb bats and Old-World bats suggests convergent evolution
Convergent evolution
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...

 of this gene in a similar light-rich environment. The Mauritian tomb bat can detect movement from a distance away, which suggests that the bat's eyesight is superior to that of other insect-eating bats. This advanced eyesight plays a large role in finding a suitable roost for the day and detecting predators. The Mauritian tomb bat is, for the most part, a nocturnal hunter, though it does occasionally forage during the day. They prefer to hunt in open spaces such as over an open field or body of water, so they can easily swoop down and grab the insects they feed on. The Mauritian tomb bat captures its prey and consumes it while in flight.

Their preferred food is moths
Moths
Moths may refer to:* Gustav Moths , German rower* The Moths!, an English indie rock band* MOTHS, members of the Memorable Order of Tin Hats...

, though during daylight hours they will prey upon butterflies and termites. In regions where the bats live, they often are a factor in keeping pest populations down. This is important since the bats inhabit areas often plagued by insect-borne diseases such as malaria
Malaria
Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...

. They usually wait for complete darkness before foraging. Over open areas, they can detect their prey at long ranges. They periodically make dives when hunting, and with each dive, they increase the rate of echolocation
Echolocation
Echolocation may refer to:* Acoustic location, the general use of sound to locate objects* Animal echolocation, non-human animals emitting sound waves and listening to the echo in order to locate objects or navigate...

.

Echolocation

The bats use audible calls to communicate with each other. When at rest, they chirrup; when faced with an aggressive situation, they screech. They use social communication, touch, and chemical cues. In its home continent of Africa, it is well known for the squeaks, chirrups, and other noises that it makes that are barely audible to humans.

When it is dark, they use echolocation
Echolocation
Echolocation may refer to:* Acoustic location, the general use of sound to locate objects* Animal echolocation, non-human animals emitting sound waves and listening to the echo in order to locate objects or navigate...

 calls to forage
Forage
Forage is plant material eaten by grazing livestock.Historically the term forage has meant only plants eaten by the animals directly as pasture, crop residue, or immature cereal crops, but it is also used more loosely to include similar plants cut for fodder and carried to the animals, especially...

. During daylight hours, they can rely on vision to look for prey and intruders. The echolocation in T. mauritianus is unique in that their frequency
Frequency
Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...

 pulses are emitted in patterns of twos and threes separated by long intervals of silence. This helps observers distinguish the species from other kinds of bats. The bats can adjust the frequency they emit to fit a given situation. For example, the bat can decrease the frequency to less than 20 Hertz
Hertz
The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....

 to hunt insects that are attuned to bat echolocation, which gives them an advantage and increases their number of potential food sources. They are capable of emitting frequencies more than 25 Hertz, which allows them to hunt in less open habitats. This increases their range of habitats, and allows them to be flexible in their choice of environments.

Mating and reproduction

Mauritian tomb bats are polygamous. Depending on the region, they mate either once or twice per year. Tomb bats of the Southern African subregion
Subregion
A subregion is a conceptual unit which derives from a larger region or continent and is usually based on location. Cardinal directions, such as south or southern, are commonly used to define a subregion.- United Nations subregions :...

 often produce two pups: one in February or March and another in October through December.
Others mate in December with a gestation period
Gestation period
For mammals the gestation period is the time in which a fetus develops, beginning with fertilization and ending at birth. The duration of this period varies between species.-Duration:...

 of four to five months, and give birth in April or May. Mothers give birth to a single pup in a litter. Mothers take care of the young after birth; the males take no part in raising it. The pup clings to its mother's abdomen
Abdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...

 during flight and when perched. The young will remain with the mother, clinging to her chest wherever she goes, until it is able to fly. The mother nurses the young during this time. The young drink their mother's milk until they are weaned onto there adult diet of insects. The time spent with the mother allows the young to observe hunting behavior as well as learn other skills necessary for survival as an adult. Once the young bat is able to fly, it can forage for itself. It may stay with the mother's colony or find another when it is grown.

Conservation

The Mauritian tomb bat is of "Least Concern (LC)" on the IUCN Red List
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...

 of endangered species
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

. Although its population and the population trend are unknown, the bat is easily found throughout its range. Mauritian tomb bats are widespread throughout Africa and neighboring islands. They are not listed as requiring special conservation action under any current programs.

Cited texts

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