Slit-Faced Bats (Nycteridae)
Slit-faced bats
(Nycteridae)
Class Mammalia
Order Chiroptera
Suborder Microchiroptera
Family Nycteridae
Thumbnail description
Small- to medium-sized bats with large ears and a tail ending in a diagnostic T-shaped cartilage; face split by a distinctive and diagnostic groove
Size
Forearms range 1.2–2.5 in (3.2–6.4 cm); body mass 0.2–1.2 oz (6–36 g)
Number of genera, species
1 genus; 14 species
Habitat
Occur from rainforest to savanna as well as in arid habitats
Conservation status
Vulnerable: 2 species; Lower Risk/Near Threatened: 3 species; Data Deficient: 1 species
Distribution
Africa, Madagascar, Southeast Asia, and East Indies
Evolution and systematics
Although slit-faced bats are included in the superfamily Rhinolophoidea, the closeness of their relationship to the other families in the group (false vampires, the Megadermatidae, horseshoe bats, the Rhinolophidae, and Old World leaf-nosed bats, the Hipposideridae) has been questioned. Apart from recent material, there is no fossil record of slit-faced bats. No subfamilies are recognized.
Physical characteristics
Slit-faced bats are small to medium in size, and have broad wings and large ears. Their fur is long and fine and ranges in color from gray to red. The T-shaped tail cartilage, large ears, and slit-faces make them distinctive.
Distribution
Most species of slit-faced bats occur in Africa, one ranging from the north (Israel and adjacent countries) to the south (the Cape). Two other species occur in Southeast Asia, from Myanmar, Thailand, and Malaysia to Sarawak, Sumatra, Java, Borneo, and Bali. One species has been reported from Madagascar.
Habitat
Most species of slit-faced bats are found in rainforest in Africa or in Southeast Asia, but other species occur in drier areas, from savanna woodlands to desert.
Behavior
Slit-faced bats roost in hollows by day. The hollows include caves and mines, those in trees, as well as others associated with buildings or other artificial structures. Roosting slit-faced bats are usually not in physical contact with one another. They produce low-intensity echolocation calls, which
they may not depend upon to find their prey, relying instead on sound cues such as the songs or footfalls of prey. Slit-faced bats also take flying prey. Accumulations of discarded pieces of prey under feeding roosts provide biologists with a picture of the diets of slit-faced bats. Unlike other species of bat, slit-faced bats are warm-blooded and cannot enter torpor, a state of total inactivity.
Feeding ecology and diet
Smaller species of slit-faced bats feed almost entirely on arthropods, typically insects such as moths, beetles, and crickets, but also spiders, centipedes, and scorpions. Larger species of nycterids also eat small vertebrates such as fish, frogs, birds, and other bats. Slit-faced bats often hunt from a perch, dropping to the ground to grab passing prey, or snatching it from the foliage or branches or trunks of trees.
Reproductive biology
A single young is born each year, typically at the beginning of the rainy season. The slit-faced bats are most likely promiscuous.
Conservation status
The intermediate slit-faced bat (Nycteris intermedia), Wood's slit-faced bat (Nycteris woodi), and N. aurita are considered by the IUCN to be Lower Risk/Near Threatened. The Javan slit-faced bat (Nycteris javanica) and Ja slit-faced bat (Nycteris major) are considered Vulnerable, the former because of declining range, the latter because of restricted range. Too little is known about the Madagascar slit-faced bat (Nycteris madagascariensis) to assess its conservation status, and it is listed as Data Deficient.
Significance to humans
None known.
Species accounts
List of Species
Large slit-faced batEgyptian slit-faced bat
Large slit-faced bat
Nycteris grandis
taxonomy
Nycteris grandis Peters, 1865, Guinea.
other common names
None known.
physical characteristics
The largest of slit-faced bats: forearms 2.2–2.6 in (5.7–6.6 cm); weight 0.8–1.2 oz (23–36 g). Long, fine fur is gray to red.
distribution
Occur from Sierra Leone in the west to Lake Victoria in the east. There are two isolated populations, one on the coast in Tanzania, the other from Zambia south into Zimbabwe along the Zambezi River.
habitat
Most often found in rainforest, but outlying populations occur in areas of savanna woodlands.
behavior
Roost in hollows in trees, caves, and mines, or those in artificial structures such as buildings and unused military bunkers. Roosting individuals, other than females and their dependent young, are not in physical contact with one another. Along the Zambezi River in Zimbabwe, they use the same day roosts year after year, including hollows in acacia trees as well as those in buildings and in military bunkers; the roosts provide shelter from the extreme heat of the day. Along the Zambezi, they use feeding roosts, sites that offer protection from above. Typically, feeding roosts are under thatched roofs, on porches, and in rooms that they enter through open doors or windows. Some day roosts also serve as feeding roosts.
feeding ecology and diet
May hang from perches and wait for passing prey, or fly in search of food. In either case, they depend upon the sounds of prey to locate their targets and usually take prey from surfaces. Along the Zambezi River, they feed heavily on vertebrates, usually frogs (representing seven species), but occasionally on birds and fish. They also eat other species of bats, including Egyptian slit-faced bats. Large slit-faced bats also eat large arthropods, including sun spiders, moths, and beetles. Prey is killed with a bite to the head, and inedible parts dropped below feeding roosts. When they eat frogs, they usually discard one foot bitten off at the ankle, the other leg bitten off at the knee.
reproductive biology
Females bear a single young each year. Probably promiscuous.
conservation status
Not listed by the IUCN.
significance to humans
None known.
Egyptian slit-faced bat
Nycteris thebaica
taxonomy
Nycteris thebaica E. Geoffroy, 1818, Egypt. Seven subspecies are recognized.
other common names
None known.
physical characteristics
A medium-sized bat; forearm ranging 1.6–2 in (4.2–5.1 cm); weight 0.2–0.4 oz (7–12 g). Long, fine fur is gray to red. Large ears.
distribution
Widespread in savanna woodlands of sub-Saharan Africa from Sierra Leone in the west through East Africa and north to the middle east on either side of the Red Sea; occur south in Africa to the Cape.
habitat
Occur in savanna woodlands and more arid areas.
behavior
Roost in hollows, whether in trees, buildings, caves, or abandoned mines. Within roosts, daytime temperatures can be around 86°F (30°C) when outside temperatures are well over 104°F (40°C). Roosting individuals are not usually in physical contact with one another, so the size of a roosting group depends upon the available space. In some cave roosts, they roost within 3.2–6.5 ft (1–2 m) of active bee hives.
feeding ecology and diet
Take prey from surfaces (the ground or vegetation) as well as flying prey. The usual diet is arthropods, from sun spiders to scorpions, and insects such as orthopterans, moths, and beetles. In Zimbabwe, Egyptian slit-faced bats ate 1.1 in (3 cm) beetles in less than two minutes. From South Africa, there is one record of an Egyptian slit-faced bat taking a lizard. These bats appear to use sounds generated by prey to detect and assess their targets. The role of echolocation in hunting remains unclear. They produce bird-like chirps when foraging at night, but the function of these calls remains unknown.
reproductive biology
Most likely promiscuous. Females produce a single young annually after a gestation period of 150 days. The birth period is typically timed to coincide with the start of the rains. Females take small young with them when they leave the roost to forage, but leave them in another secure place while actually hunting.
conservation status
Not listed by the IUCN.
significance to humans
None known.
| Common name / Scientific name / Other common names | Physical characteristics | Habitat and behavior | Distribution | Diet | Conservation status |
| Bate's slit-faced bat Nycteris arge | Light brown above, ventral side is lighter brown or grayish white. Medium-sized bat with large ears and well-developed calcar. Muzzle has deep median furrow. Head and body length 3.8–4.3 in (9.7–11 cm), tail length 1.8–2.2 in (4.7–5.8 cm), forearm length 1.6–1.9 in (4.3–4.7 cm). | Woodland savanna or dry country. Solitary. | Sierra Leone to southern and eastern Democratic Republic of the Congo; western Kenya; southwestern Sudan; northeastern Angola; and Bioko. | Variety of arthropods, including moths, butterflies, other insects, spiders, and sun spiders. | Not threatened |
| Gambian slit-faced bat Nycteris gambiensis | Pelage varies from rich brown or russet to pale brown or grayish. Muzzle has longitudinally divided nostrils, which are long, deep pit in forehead. T-shaped tip at end of tail. Head and body length 1.5–3.7 in (4–9.3 cm), tail length 1.7–3 in (4.3–7.5 cm), forearm length 1.2–2.4 in (3.2–6 cm). | Woodland savanna or dry country. Very gregarious. | Senegal, Gambia, Guinea, Sierra Leone, Ghana, Togo, Benin, and Burkina Faso. | Variety of arthropods, including moths, butterflies, other insects, spiders, and sun spiders. | Not threatened |
| Hairy slit-faced bat Nycteris hispida | Pelage varies from rich brown or russet to pale brown or grayish. Muzzle has longitudinally divided nostrils, which are long, deep pit in forehead. T-shaped tip at end of tail. Head and body length 1.5–3.7 in (4–9.3 cm), tail length 1.7–3 in (4.3–7.5 cm), forearm length 1.2–2.4 in (3.2–6 cm). | Woodland savanna or dry country. Group size may reach up to 20 individuals. Females begin new gestation while nursing the first offspring. May roost in hollow trees, dense foliage, rocky outcrops, caves, buildings, ruins, culverts, and abandoned wells. | Senegal to Somalia and south to Angola and South Africa; Zanzibar; and Bioko. | Variety of arthropods, including moths, butterflies, other insects, spiders, and sun spiders. | Not threatened |
| Intermediate slit-faced bat Nycteris intermedia French: Nyctère moyen | Pelage varies from rich brown or russet to pale brown or grayish. Muzzle has longitudinally divided nostrils, which are long, deep pit in forehead. T-shaped tip at end of tail. Head and body length 1.5–3.7 in (4–9.3 cm), tail length 1.7–3 in (4.3–7.5 cm), forearm length 1.2–2.4 in (3.2–6 cm). | Woodland savanna or dry country. May roost in hollow trees, dense foliage, rocky outcrops, caves, buildings, ruins, culverts, and abandoned wells. | Liberia to western Tanzania and south to Angola. | Variety of arthropods, including moths, butterflies, other insects, spiders, and sun spiders. | Lower Risk/Near Threatened |
| Javan slit-faced bat Nycteris javanica French: Nyctère de Java | Varies from rich brown or russet to pale brown or grayish. Muzzle has longitudinally divided nostrils, which are long, deep pit in forehead. T-shaped tip at end of tail. Head and body length 1.5–3.7 in (4–9.3 cm), tail length 1.7–3 in (4.3–7.5 cm), forearm length 1.2–2.4 in (3.2–6 cm). | Dense forests. Breeds through-out year and females mate again shortly after giving birth. | Java, Bali, and Kangean Islands, Indonesia. | Variety of arthropods, including moths, butterflies, other insects, spiders, and sun spiders. | Vulnerable |
| Large-eared slit-faced bat Nycteris macrotis German: Groβohr-Schlitznase | Varies from rich brown or russet to pale brown or grayish. Exhibits considerable orange color variation in Democratic Republic of the Congo (Zaire). Muzzle has longitudinally divided nostrils, which are long, deep pit in forehead. T-shaped tip at end of tail. Head and body length 1.5–3.7 in (4–9.3 cm), tail length 1.7–3 in (4.3–7.5 cm), forearm length 1.2–2.4 in (3.2–6 cm). | Woodland savanna or dry country. Females nurse young for 45–60 days. Generally shelters in caves in pairs or alone. | Senegal to Ethiopia, south to Zimbabwe, Malawi and Mozambique; Zanzibar; and Madagascar. | Variety of arthropods, including moths, butterflies, other insects, spiders, and sun spiders. | Not threatened |
| Common name / Scientific name / Other common names | Physical characteristics | Habitat and behavior | Distribution | Diet | Conservation status |
| Ja slit-faced bat Nycteris major | Pelage varies from rich brown or russet to pale brown or grayish. Muzzle has longitudinally divided nostrils, which are long, deep pit in forehead. T-shaped tip at end of tail. Head and body length 1.5–3.7 in (4–9.3 cm), tail length 1.7–3 in (4.3–7.5 cm), forearm length 1.2–2.4 in (3.2–6 cm). | Woodland savanna or dry country. Little known of reproductive and behavioral patterns. | Liberia to Zambia. | Variety of arthropods, including moths, butterflies, other insects, spiders, and sun spiders. | Vulnerable |
Resources
Books
Garbutt, N. Mammals of Madagascar. New Haven: Yale University Press, 1999.
Hutson, A. M., S. P. Mickelburgh, and P. A. Racey. Global Status Survey and Conservation Action Plan, Microchiropteran Bats. Gland, Switerzland: IUCN SSC Chiroptera Specialist Group, 2001.
Kingdon, J. Mammals of East Africa: An Atlas of Evolution, Volume 2b. New York: Academic Press, 1974.
Nowak, R. M. Walker's Mammals of the World, Volume 1. Baltimore: Johns Hopkins University Press, 1999.
Payne, J., C. M. Francis, and K. Phillips. A Field Guide to the Mammals of Borneo. Kuala Lumpur: The Sabah Society with World Wildlife Fund Malaysia, 1985.
Taylor, P. J. Bats of Southern Africa. Pietermaritzburg, South Africa: University of Natal Press, 2000.
Periodicals
Aldridge, H. D. J. N., M. Obrist, H. G. Merriam, and M. B. Fenton. "Roosting, Vocalizations and Foraging by the African Bat, Nycteris thebaica." Journal of Mammalogy 71 (1990): 242–246.
Fenton, M. B., C. L. Gaudet, and M. L. Leonard. "Feeding Behaviour of the Bats Nycteris grandis and Nycteris thebaica (Nycteridae) in Captivity." Journal of Zoology 200 (1983): 347–354.
Fenton, M. B., C. M. Swanepoel, R. M. Brigham, J. Cebek, and M. B. C. Hickey. "Foraging Behaviour and Prey Selection by Large Slit-faced Bats (Nycteris grandis; Chiroptera: Nycteridae)." Biotropica 22 (1990): 2–8.
Gray, P. A., M. B. Fenton, and V. Van Cakenberghe. "Nycteris thebaica." Mammalian Species 612 (1999): 1–8.
Hickey, M. B. C., and J. M. Dunlop. "Nycteris grandis." Mammalian Species 632 (2000).
Melville Brockett Fenton, PhD