Is the Hammer-Headed Bat a Real Animal?

The bat that uses its hammer-shaped head to sing

Hammer-headed bat
Hammer-headed bat. ​Proceedings of the Zoological Society of London 1862

The hammer-headed bat is a real animal, and its scientific name (Hypsignathus monstrosus) references its monstrous appearance. Indeed, websites and social media describe the hammer-headed bat's appearance as "the spitting image of a devil" and even claim that it's a cryptid known as the "Jersey Devil." Despite its fearsome attributes, however, this bat is a mild-mannered fruit-eater. Nevertheless, you shouldn't get too close, because it's one three species of African fruit bat believed to carry the Ebola virus.

Fast Facts: Hammer-Headed Bat

  • Scientific Name: Hypsignathus monstrosus
  • Other Names: Hammerhead bat, big-lipped bat
  • Distinguishing Features: Large brown bat characterized by males having a hammer-shaped face, while females have fox-like faces
  • Average Size: Wingspan 686 to 970 mm (27.0 to 38.2 in); total length of 195 to 285 mm (7.7 to 11.2 in)
  • Diet: Fruit
  • Lifespan: 30 years
  • Habitat: Low elevations of equatorial Africa
  • Conservation Status: Least Concern
  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Mammalia
  • Order: Chiroptera
  • Family: Pteropodidae
  • Fun Fact: A male bat's larynx extends half the length of its spinal column.

Description

The hammer-headed bat is a type of megabat and the largest bat native to Africa. Both males and females are grayish brown, with brown ears and flight membranes, and tufts of white fur at the base of the ears. An adult bat ranges from 195 to 285 mm (7.7 to 11.2) in body length, with a wingspan of 686 to 970 mm (27.0 to 38.2 in). Males range in weight from 228 to 450 g (8.0 to 15.9 oz), while females weigh 218 to 377 g (7.7 to 13.3 oz).

Male hammer-headed bats are larger than females and look so different from their mates that it would be easy to think they belonged to a different species. Only the males have large, elongated heads. Female hammer-headed bats have the fox-faced appearance common to most fruit bats.

This hammer-headed bat looks unnaturally large because it is closer to the camera than its handler.
This hammer-headed bat looks unnaturally large because it is closer to the camera than its handler. Per Se, Flickr

The hammer-headed bat is sometimes confused with Wahlberg's epauletted fruit bat (Epomophorus wahlbergi), which belongs to the same family but is smaller.

Wahlberg's epauletted fruit bat (Epomophorus wahlbergi) also has a hammer-head face.
Wahlberg's epauletted fruit bat (Epomophorus wahlbergi) also has a hammer-head face. Michele D'Amico supersky77 / Getty Images

Distribution

Hammer-headed bats occur across equatorial Africa at elevations below 1800 m (5900 ft). They favor humid habitats, including rivers, swamps, mangroves, and palm forests.

Hammer-headed bat distribution map
Hammer-headed bat distribution map. Chermundy

Diet and Predators

Hammer-headed bats are frugivores, which means their diet consists entirely of fruit. While figs are their favored food, they also eat bananas, mangoes, and guavas. The bat has a longer intestine than that of an insectivorous species, allowing it to absorb more protein from its food. There is a sole report of a bat eating a chicken, but no carnivorous activity has been substantiated.

The bats are preyed upon by humans and birds of prey. They are also susceptible to severe parasite infestations. Hammer-headed bats are prone to infection by mites and Hepatocystis carpenteri, a protozoan that affects the liver. The species is a suspected reservoir for the Ebola virus, but as of 2017, only antibodies against the virus (not the virus itself) have been found in the animals. Whether or not the bats can transmit Ebola infection to humans is unknown.

Behavior

During the day, the bats roost in trees, relying on their coloration to camouflage them from predators. They pick and eat fruit at night. One reason large bats such as the hammer-headed bat are nocturnal is because their bodies generate considerable heat when they are flying. Being active at night helps keep the animals from overheating.

Reproduction

Breeding takes place during dry seasons for some populations and at any time of the year for others. Most members of this bat species reproduce via lek mating. In this type of mating, males gather in groups of 25 to 130 individuals to perform a mating ritual consisting of wing flapping and loud honking. Females fly through the group to evaluate potential mates. When a female's selection is made, she lands beside a male and mating occurs. In some hammer-headed bat populations, males perform their display to attract females, but do not form groups.

Females usually give birth to one offspring. The time required for gestation and weaning is unclear, but females are known to mature more quickly than males. Females reach sexual maturity at 6 months of age. It takes males a full year to develop their hammer-head faces and about 18 months before they reach maturity. The bat has a life expectancy of thirty years in the wild.

Conservation Status

The conservation status of the hammer-headed bat was last evaluated in 2016. The bat is categorized as "least concern." Although the animal is hunted as bush meat, it occupies a large geographic range and the overall population has not experienced a rapid decline.

Sources

  • Bradbury, J. W. (1977). "Lek Mating Behavior in the Hammer-headed Bat". Zeitschrift für Tierpsychologie 45 (3): 225–255. doi:10.1111/j.1439-0310.1977.tb02120.x
  • Deusen, M. van, H. (1968). "Carnivorous Habits of Hypsignathus monstrosus". J. Mammal. 49 (2): 335–336. doi:10.2307/1378006
  • Langevin, P.; Barclay, R. (1990). "Hypsignathus monstrosus". Mammalian Species 357: 1–4. doi:10.2307/3504110
  • Nowak, M., R. (1994). Walker's Bats of the World. Johns Hopkins University Press. pp. 63–64.
  • Tanshi, I. (2016). "Hypsignathus monstrosus". The IUCN Red List of Threatened Species. 2016: e.T10734A115098825. doi:10.2305/IUCN.UK.2016-3.RLTS.T10734A21999919.en