Identification:
Forearm length: 37 – 72 mm. Members of the family Rhinolophidae are characterized by a horseshoe-shaped anterior noseleaf, a tall and pointed posterior noseleaf, large ears without a tragus, and a moderately long tail enclosed within the interfemoral membrane. All species in this family are currently classified under a single genus, Rhinolophus, with nearly 60 species worldwide, including 30 species in the region. The shape and size of the noseleaf vary significantly among species.
Some species possess accessory leaflets at the base of the noseleaf, while others have tufts of hair on their backs. Echolocation calls are composed of distinct, constant-frequency components that allow them to detect moving prey through the “Doppler” effect (the same principle used in radar to measure the speed of moving objects). The flapping wings of moths cause a change in the sound frequency, enabling the bats to differentiate insects from nearby leaves. These sounds are all beyond the human hearing range, from 23 kHz to over 100 kHz.
Each species has a distinct echolocation frequency, which is adapted to its internal hearing structures, body size, and noseleaf shape. The presence of the noseleaf helps focus the emitted echolocation calls through the nose. The purpose of the intricate structures on the noseleaf is not fully understood; however, species with lower frequency calls (longer wavelengths) tend to have larger noseleaves and ears. Up to 10 species may be found in a given forest area, preying on different insect species based on their echolocation calls and body size (high-frequency calls are more effective for finding smaller prey).
Biology, Ecology:
The family Rhinolophidae, with most species inhabiting caves, often forms large colonies of thousands, sometimes even hundreds of thousands. They also occasionally form smaller colonies in tree hollows or rock crevices. A few species live among dead leaves in trees, including Rhinolophus trifoliatus, which has yellowish and light brown fur that may aid in camouflage.
Other species are dark brown or gray, but many are bicolored, and some have bright orange or reddish fur. Long-eared horseshoe bats typically give birth to one offspring, and the young remain with their mothers throughout the day, hanging in the cave while the mothers forage at night. These species are found throughout Southeast Asia.
Distribution:
Species of the family Rhinolophidae are widely distributed throughout Southeast Asia, including Thailand, Laos, Vietnam, Malaysia, the Philippines, and Borneo.