Trefoil Horseshoe Bat (Rhinolophus trifoliatus)
HB: 60-70; T: 30-38; FA: 47-55; E: 25-27; HF: 11-12.
This striking and charismatic bat is identifiable by its yellow nose leaf and long, soft, fluffy, greyish-brown fur. The elbows, knees and ears are also yellow, deepening in colour with age. The wings are a light, almost orangey, brown, and the membrane also stretches between the hind legs, enclosing most of the tail. As a member of the horseshoe bat family, the nose leaf of this species is shaped like a horseshoe, with a projection that looks somewhat like a horn above it called the connecting process. This probably serves to focus the ultrasonic pulses during echolocation. The ears are large to receive the echoes. The Trefoil Horseshoe Bat is a small to medium-sized member of the Horseshoe Bat family or Rhinolophidae, which includes over 30 species in Southeast Asia. These bats are masters of echolocation, swooping down on moths and other insects in the under story of Primary Forest. The complicated nose leaf, used for detecting echoes bouncing from its prey, and distinctive ears of this species are yellow. The fur is thick and woolly and can vary from buff to grey. The fur is thick and furry, with the individual hairs buff at the base, lightly tipped with dull brown, the under parts are lighter. The nose leaf is similar to luctus but smaller; the erect transverse process of the sella is narrower above. The margin of the interfemoral membrane is straight, narrowly bordered with yellow between the tip of the tale and the calcar; the extreme tip of the tai projects. The skull as a triangular pit just behind the 4 nasal swellings, the 2 middle swellings are situated close together. The sagittal crest is prominent in the frontal region, less prominent towards the rear. The lower second premolar is variable, and can be in the tooth row. The first and third premolars may be in contact.
This species is widely distributed in Southeast Asia, with
additional records from South Asia and China. In Southeast Asia, it has been
recorded from southern Myanmar and Thailand, into Peninsular Malaysia,
and from here into Indonesia (including the Mentawi Islands [Nias], Sumatra,
Bangka, Billiton, Java and Banta), ranging to the island of Borneo (Brunei,
Indonesia and Malaysia). In South Asia, it is presently known from Assam and
West Bengal in India, recorded up to an elevation of 1,800 m asl (Molur et al.
2002). In China, it is known only from a single specimen recorded from Guizhou
(Jinsha) (Wang 2002; Smith and Xie 2008).
China; India; Indonesia (Jawa, Kalimantan, Sumatera); Malaysia (Peninsular Malaysia, Sabah, Sarawak); Myanmar; Thailand
In Southeast Asia, this species is generally considered
to be common in intact forest habitats. It is considered to be uncommon on the
island of Sumatra (Indonesia). The abundance, population size and trends for
this species in South Asia are not known (Molur et al. 2002).
Population Trend: Unknown
Habitat and Ecology:
In Southeast Asia, it has been recorded from primary and
secondary tropical moist forest. It is generally considered a lowland species on
Borneo and elsewhere in the region. Animals roost singly under leaves or palm
leaves in the forest under story, and are believed to breed once a year. In South
Asia, little is known about the habitat or ecology of this species except that
it is found in dense evergreen forests. (Molur et al. 2002). An insectivore, the
trefoil horseshoe bat catches its prey by ‘perch hunting’; it hangs from a
branch at a height of around three metres above the forest floor, with a
clearing beneath, and waits for insects to pass. Once it has detected them using
echolocation, emitted from the nose leaf, it drops from the perch and pursues
the insect, returning to a hanging position to eat it. This species uses long
pulses of a constant frequency to detect the flutter of an insect’s wings. The
trefoil horseshoe bat gives birth to a single pup which it suckles for several
months before the pup is able to fly and catch insects alone. The pup begins
life weighing two to five grams; a large proportion of its mother’s weight. By
one year of age it is fully grown and ready to have a pup of its own.
This species is threatened over much of its range by
deforestation, generally resulting from logging operations and the conversion of
land to agricultural use. In South Asia, the development of tourism related
activities is also considered to be a major threat (Molur et al. 2002).
It has been recorded from a number of protected areas in Southeast Asia. In South Asia, there are no direct conservation measures in place for this species. Survey, ecological and population monitoring are recommended (Molur et al. 2002).