The Hammer-headed bat is a large fruit bat found in Africa. Males and females greatly differ in appearance which makes it the most sexually dimorphic bat species in the world. These differences include several adaptations that help males produce and amplify vocalizations: the males' larynges (vocal cords) are about three times as large as those of females, and they have large resonating chambers on their faces. Males overall have boxy heads with enormous lips, while the females, with their narrower snouts, have more foxlike faces. Males and females both have dark brown fur, with a paler mantle (sides and back of neck). They have patches of white fur at the base of the ears, though sometimes indistinct. The fur is long and smooth, though somewhat woolly in texture on the mantle. The ears are triangular and blackish-brown, and the eyes are very large.
Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal",...
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example, foliage, for the main component of its die...
A frugivore is an animal that thrives mostly on raw fruits or succulent fruit-like produce of plants such as roots, shoots, nuts, and seeds. Approx...
An insectivore is a carnivorous plant or animal that eats insects. An alternative term is entomophage, which also refers to the human practice of e...
Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some anima...
Nomadic animals regularly move to and from the same areas within a well-defined range. Most animals travel in groups in search of better territorie...
A territory is a sociographical area that which an animal consistently defends against the conspecific competition (or, occasionally, against anima...
Terrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
Among animals, viviparity is the development of the embryo inside the body of the parent. The term 'viviparity' and its adjective form 'viviparous'...
Polygyny is a mating system in which one male lives and mates with multiple females but each female only mates with a single male.
NoNot a migrant
Animals that do not make seasonal movements and stay in their native home ranges all year round are called not migrants or residents.
Hammer-headed bats are found in West and Central Africa, including the following countries: Angola, Benin, Burkina Faso, Cameroon, Central African Republic, Republic of the Congo, Democratic Republic of the Congo, Ivory Coast, Equatorial Guinea, Ethiopia, Gabon, Ghana, Guinea, Guinea-Bissau, Kenya, Liberia, Nigeria, Sierra Leone, Sudan, Togo, and Uganda. They inhabit lowland rainforest, swamp forest, riverine forests, mangroves, and mosaics of forest and grassland.
Hammer-headed bats are nocturnal creatures and sleep during the day in tree roosts. They may roost alone or in small groups and unlike many other bat species that segregate based on sex, male and female Hammer-headed bats will roost together in small groups of around four individuals. Occasionally, groups of up to twenty-five have also been documented. While roosting, individuals in a group are approximately 10-15 cm (3.9-5.9 in) apart, with males on the periphery and females nearer the center. During most of the day, bats sleep with their noses covered by their wings. Members of the same group show little interaction with each other: they do not "squabble", vocalize, or groom each other. Instead, at sunset, they groom themselves then set off independently to forage. Males and females rely on different strategies for foraging. Females use trap-lining, in which they travel an established route with dependable and predictable food sources, even if the food is of lower quality. Males, in contrast, search for areas rich with food, traveling up to 10 km (6.2 mi) to reach particularly good food patches. Upon finding suitable fruit, Hammer-headed bats may eat at the tree or pick the fruit and carry it away to another site for consumption. They chew the fruit, swallowing the juice and soft pulp, before spitting out the rest.
Hammer-headed bats are polygynous meaning that males mate with more than one female. Their breeding season lasts 1-3 months and occurs from June to August and from December to February. These bats exhibit classical lek mating and are perhaps the only bats with such. Males gather in a particular region, known as a lek and there they establish "display territories". These leks are usually formed along streams or riverbeds and consist of 20-135 males. Each male claims a display territory of about 10 m (33 ft) in diameter, in which he honks repeatedly and flaps his wings while hanging from a branch. Males display for around four hours before foraging, with peaks in lekking activity in the early evening and before dawn. Females will fly through the lek, selecting a male by landing on a branch next to him and the chosen male emits a "staccato buzz" call. After mating, the female immediately departs, and the male resumes displaying. However, some populations of Hammer-headed bats in West Africa do not use leks. Instead, they have a harem system. Females may become pregnant up to twice per year, giving birth to one offspring at a time, though twins have been reported. The gestation period lasts around 5 or 6 months. Newborns weigh approximately 40 g (1.4 oz) at birth. Males do not assist females in caring for offspring. Females reach reproductive maturity faster than males; they can reproduce at six months and reach adult size by nine months of age. In contrast, males become reproductively mature when they are eighteen months old.
The biggest threat to Hammer-headed bats is habitat destruction. They are also persecuted as pests due to their frugivorous diet and their extremely loud honking noises at night. In Nigeria and the Democratic Republic of the Congo, these bats are hunted and consumed as bushmeat.
According to IUCN, the Hammer-headed bat is locally common and widespread throughout its range but no overall population estimate is available. Currently, this species is classified as Least Concern (LC) on the IUCN Red List.
Due to their frugivorous diet Hammer-headed bats are important seeds dispersers in their ecosystem and they also serve as a food source for some birds of prey.