Wahlberg’s Epauletted Fruit Bat
- Epomophorus wahlbergi
- IUCN Status: Least Concern
- Trend: stable
General Information
Wahlberg’s epauletted fruit bat (Epomophorus wahlbergi) is a species of megabat in the family Pteropodidae. It is commonly found across southern Africa.
Description
Wahlberg’s epauletted fruit bat is brown to tawny colored with white hair patches at the base of the ears. Males are typically darker in coloration than females. This species is named for erectable epaulettes of hair that form around large scent glands in males only. Males are also distinguished from females by air sacs on the neck that may increase the volume of courtship calls. Scent glands are located near the white ear patches in both sexes. Wings are broad as compared to other bat species. Adult wingspan is 510–600 mm and 456–540 mm for males and females, respectively. Adults weight 54–125 g.
The eyes of E. wahlbergi are large. Ears are simple, oval-shaped, and lack a tragus. The nose is also simple, but the lips are highly folded and expansible. Skulls are 44–57 mm and 41–49 mm long for males and females, respectively.
Species of the genus Epomophorus can be distinguished from other megabats (Family Pteropodidae) by their eponymous white epaulettes. A single post-dental palatal ridge in E. wahlbergi distinguishes this species from other members of the genus.
Ecology & Behaviour
E. wahlbergi is nocturnal. It roosts in well-lit open trees, under palm fronds, in dense forests near rivers, under thatched roofs of sheds, and, rarely, in caves. Roosting groups may be 3–100 individuals. Bats typically change roost locations daily or every few days and may fly as far as 4 km to feeding areas. Roost locations may follow the ripening of fruit trees. Alternatively, frequently changing roost sites may be a strategy to decrease predation. Females travel greater distances to feeding areas early in the night while males travel farther closer to dawn. Roost trees may be shared with other Epomophorus species, though roosting groups are formed by single species.
While roosting, E. wahlbergi is camouflaged by cryptic fur patterns. White ear spots are present in all members of the genus Epomophorus and may function to break up the outline of the head when viewed from below.
Though it does not enter torpor, E. wahlbergi is heterothermic, lowering its core body temperature while roosting. In winter, this heterothermy is more pronounced. Portions of the geographic range of E. wahlbergi incur the largest seasonal temperature variations of the entire Afrotropical region. Metabolic rates increase up to 30% during the winter as compared to summer, allowing individuals to overcome heat loss in lower ambient temperatures. Body mass also increases in winter. An individual’s thermoneutral zone may also be broader in the winter than in the summer, allowing a greater temperature tolerance and thus decreasing energy expenditure typically used to compensate for minor changes in core body temperature. In times of heat stress, excessive salivation, wing fanning, body licking, and panting help to lower body temperature. Some individuals are intolerant of extreme heat and die at temperatures greater than 40 °C.
Distribution & Habitat
Wahlberg’s epauletted fruit bat is found across southern Africa in forest, shrubland, and savanna habitats at altitudes from sea level up to 2,000 m. Populations have also been found in wooded urban areas and roosting in man-made structures.
Diet
E. wahlbergi is nocturnal. It roosts in well-lit open trees, under palm fronds, in dense forests near rivers, under thatched roofs of sheds, and, rarely, in caves. Roosting groups may be 3–100 individuals. Bats typically change roost locations daily or every few days and may fly as far as 4 km to feeding areas. Roost locations may follow the ripening of fruit trees. Alternatively, frequently changing roost sites may be a strategy to decrease predation. Females travel greater distances to feeding areas early in the night while males travel farther closer to dawn. Roost trees may be shared with other Epomophorus species, though roosting groups are formed by single species.
While roosting, E. wahlbergi is camouflaged by cryptic fur patterns. White ear spots are present in all members of the genus Epomophorus and may function to break up the outline of the head when viewed from below.
Though it does not enter torpor, E. wahlbergi is heterothermic, lowering its core body temperature while roosting. In winter, this heterothermy is more pronounced. Portions of the geographic range of E. wahlbergi incur the largest seasonal temperature variations of the entire Afrotropical region. Metabolic rates increase up to 30% during the winter as compared to summer, allowing individuals to overcome heat loss in lower ambient temperatures. Body mass also increases in winter. An individual’s thermoneutral zone may also be broader in the winter than in the summer, allowing a greater temperature tolerance and thus decreasing energy expenditure typically used to compensate for minor changes in core body temperature. In times of heat stress, excessive salivation, wing fanning, body licking, and panting help to lower body temperature. Some individuals are intolerant of extreme heat and die at temperatures greater than 40 °C.
Reproduction
E. wahlbergi is nocturnal. It roosts in well-lit open trees, under palm fronds, in dense forests near rivers, under thatched roofs of sheds, and, rarely, in caves. Roosting groups may be 3–100 individuals. Bats typically change roost locations daily or every few days and may fly as far as 4 km to feeding areas. Roost locations may follow the ripening of fruit trees. Alternatively, frequently changing roost sites may be a strategy to decrease predation. Females travel greater distances to feeding areas early in the night while males travel farther closer to dawn. Roost trees may be shared with other Epomophorus species, though roosting groups are formed by single species.
While roosting, E. wahlbergi is camouflaged by cryptic fur patterns. White ear spots are present in all members of the genus Epomophorus and may function to break up the outline of the head when viewed from below.
Though it does not enter torpor, E. wahlbergi is heterothermic, lowering its core body temperature while roosting. In winter, this heterothermy is more pronounced. Portions of the geographic range of E. wahlbergi incur the largest seasonal temperature variations of the entire Afrotropical region. Metabolic rates increase up to 30% during the winter as compared to summer, allowing individuals to overcome heat loss in lower ambient temperatures. Body mass also increases in winter. An individual’s thermoneutral zone may also be broader in the winter than in the summer, allowing a greater temperature tolerance and thus decreasing energy expenditure typically used to compensate for minor changes in core body temperature. In times of heat stress, excessive salivation, wing fanning, body licking, and panting help to lower body temperature. Some individuals are intolerant of extreme heat and die at temperatures greater than 40 °C.
References
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- Kingdom: Animalia
- Phylum: Chordata
- Class: Mammalia
- Order: Chiroptera
- Family: Pteropodidae
- Genus: Epomophorus
- Weight: 40 to 120 g
- Lifespan: avg. 10 yrs
