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Hammer-headed Bat - Hypsignathus monstrosus
Topic Started: Jan 7 2012, 02:04 PM (4,817 Views)
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Hammer-headed Bat - Hypsignathus monstrosus

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Hypsignathus monstrosus Allen, 1861, Gabon.

English: Horse-faced bat; German: Hammerkopf.


Head and body length, 7.9 in (20 cm); forearm length, 4.6–5.4 in (11.8–13.7 cm); wingspan, 35.4 in (90 cm). These bats exhibit the greatest sexual dimorphism of any member of the order Chiroptera. Males are twice the size of females. They weigh 14.8 oz (420 g), while females weigh 8.3 oz (234 g). This is the largest African fruit bat. Pelage is grayish brown with a lighter ventrum. Females have a fox-like face and resemble Epomophorus. Males have a very different appearance, probably as a result of a form of sexual selection called "female choice." The skull is elongated presenting a hammer-like appearance. The muzzle is inflated and widened at the front and covered by large cheek pouches, which serve as a resonating chamber. There is an enlarged larynx that fills much of the thoracic cavity and enables them to make a booming frog-like croaking. The large extensible lips form a "megaphone."

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Western and central Africa.

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Found primarily in tropical rainforest. Also located in swamps, mangroves, and gallery forest.
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Longest known lifespan in wild
30 years (average)
The hammerhead bat has a life expectancy of up to 30 years (Kulzer, 1990).


The most significant behavior was described by Bradbury in 1977. Hammer-headed bats are one of the few vertebrates that use arenas or leks for mating. Males aggregate twice a year in an area and fight for territories. The leks consist of from 25 to 130 males. When the females arrive the males display by making honking calls and flapping their wings. The females choose the males they wish to mate with. Seventy-nine percent of the matings are performed by only 6% of the males in any one breeding season.

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Males eat figs, females and juveniles consume softer fruits. It has been suggested that males consume the more nutritious figs because they need the additional energy for displays.


Polygamous. Two breeding seasons, June-August and December-January. One offspring is the norm. Females mature within six months of birth, males within 18 months. See behavior above.

Economic Importance for Humans: Negative
This species has been reported to kill chickens
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