Identification
The Acuminate Horseshoe Bat is a medium-sized chiropteran (forearm 44–50 mm) defined by its intricate facial architecture. Its fur is dense and woolly, typically a rich snuff-brown or grayish-buff, often paler on the underbelly. To distinguish it from the similar Intermediate Horseshoe Bat (*R. affinis*), look closely at the "sella"—the central projection of the noseleaf. In *acuminatus*, the sella is concave-sided with a sharply pointed (acuminate) tip, giving the species its name. This pointed structure is a vital field mark for any researcher peering into a roost.
Habitat & Range
This species is a Southeast Asian specialist, ranging from Thailand and Cambodia through the Malay Peninsula to the islands of Java, Sumatra, and Borneo. It is a creature of the lowlands, favoring primary rainforests but proving resilient enough to inhabit disturbed secondary growth and orchards. You will most often find them tucked away in the humid shadows of limestone caves, though they frequently utilize the hollowed-out boles of ancient trees or even rural buildings.
Behaviour
In the field, you’ll notice their incredible maneuverability. These are "clutter-specialists," weaving through dense tropical foliage where larger bats would struggle. They are moderately social, typically roosting in small colonies of a few dozen individuals, though solitary males are often encountered. They emerge at dusk, using sophisticated constant-frequency echolocation to navigate the "acoustic jungle" of the forest understory.
Diet
They are dedicated insectivores, primarily targeting Lepidoptera (moths) and Coleoptera (beetles). They utilize a "sit-and-wait" hunting strategy from low perches or engage in slow, methodical flight to snatch prey mid-air with surgical precision.
Fascinating Fact
The "horseshoe" isn't just an ornament; it’s an acoustic lens! While most bats shout through their mouths, *R. acuminatus* broadcasts its echolocation pulses through its nostrils. The complex folds of the noseleaf act like a parabolic dish, focusing the sound into a narrow, high-frequency beam that can detect a single fluttering moth wing amidst a wall of leaves.