Name: Hammer-headed bat (Hypsignathus monstrosus)
Where it lives: Lowland forests of West and Central Africa
What it eats: Fruit — including figs, bananas, guavas and mangoes — and flies
Why it’s awesome: These “megabats” are the largest in continental Africa. Hammer-headed bats are named after the males’ oddly elongated, boxy heads, which contain a large resonating chamber that amplifies their calls. This bizarre head is the product of the bats’ unusual mating system.
Hammer-headed bats are among the few bat species with a lek courtship system — a kind of pageant where up to 150 males gather twice a year to impress females with loud honks and a wing-flapping display.
We went to check out a spot that locals had told us bats gather at night. Turns out it was a hammer-headed bat lek! pic.twitter.com/18juGmlliVJanuary 14, 2022
Males hang from riverside trees and honk for hours at a time, while females fly by selecting a suitable mate. Females are highly picky, choosing the same 6% of males as mates 79% of the time (meaning the other 94% of males only get lucky once in a blue moon). The loudest honks usually get the most attention, so males have evolved a voice box, or larynx, that takes up around half their body cavity.
Their larynx is so large it pushes the heart, lungs and intestines back and sideways, according to a 1990 study.
Related: Honduran white bats — The fluffy little bats that roost together in leaf tents
The males’ calls echo inside their thorax and bizarre, gargoyle-like heads before projecting out through their flared nostrils and pendulous lips. This elaborate head likely inspired the hammer-headed bat’s Latin species name “monstrosus,” which translates to “monstrous.”
Females don’t need big heads to impress a mate, so they sport narrower fox-like muzzles instead. Their bodies are also smaller, weighing about half as much as males — 0.5 pound (230 grams) compared with 0.9 pound (420 g) — and measuring around 8 inches (20 centimeters) long, compared with up to 11 inches (28 cm) for males.
However, both males and females have about a 3.3-foot (1 meter) wingspan and smooth, grayish-brown fur.
Although they are frugivorous, meaning they eat fruit, hammer-headed bats are thought to occasionally turn carnivorous. A 1968 study reported observations of these bats feeding on scraps of bird meat and killing chickens to drink their blood in Gabon. The observer, a herpetological collector named Harry Andrew Beatty, twice rescued chickens that were “attacked late at night by Hypsignathus,” according to the study.
Another fun fact about hammer-headed bats? They wrap their huge wings around their humped noses to go to sleep.
Daisy Hips is a science communicator who brings the wonders of the natural world to readers. Her articles explore breakthroughs in various scientific disciplines, from space exploration to environmental conservation. Daisy is also an advocate for science education and enjoys stargazing in her spare time.
