Trefoil horseshoe bat  (Rhinolophus trifoliatus)

This striking and charismatic bat is identifiable by its yellow noseleaf 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 noseleaf of this species is shaped like a horseshoe, with a projection that looks somewhat like a horn above it called the connecting process (3). This probably serves to focus the ultrasonic pulses during echolocation. The ears are large to receive the echoes (4).

The trefoil horseshoe bat is historically recorded in Brunei, north east India, south west Thailand, Indonesia (Java, Kalimantan, Sumatra), Malaysia (Peninsular Malaysia, Sarawak, and Sabah), Singapore, Burma, Riau Archipelago, Banguey Island, Banka Island and Nias Island (Indonesia), but updated surveys are required to confirm populations (1) (5).

Occupying forests, including peat swamp and mangroves, the trefoil horseshoe bat feeds amongst the vegetation of the understorey and roosts there alone under dead leaves and palms. It has also been found in caves (2).

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 noseleaf, it drops from the perch and pursues the insect, returning to a hanging position to eat it (2) (3). This species uses long pulses of a constant frequency to detect the flutter of an insect's wings (4).

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 (3).

The predominant threat to the trefoil horseshoe bat is habitat loss by deforestation for timber or agriculture. Extensive amounts of forest have been lost in the last 20 years due to a rapid increase in land devoted to commodity agriculture (for example cocoa, coffee, oil palm, rice and rubber). In Malaysia and Indonesia there has recently been a large amount of deforestation in order to produce oil palm. Together, Malaysia and Indonesia export 88 percent of the world's palm oil, for use in products such as margarine, lipstick and detergent. Deforestation continues at a steady rate for conversion to agricultural land and building communities, and despite the contribution of many bats in the control of insect crop pests, persecution of bats is also a threat (6).

Deforestation for agriculture, particularly for oil palm plantations in recent years in Malaysia, Indonesia and Thailand, is an issue of major concern for many forest-dwelling species, even within so-called protected areas. Regarding oil palm, some companies and large retailers have agreed to source palm oil from sustainable sources via a certification process developed by the Roundtable for Sustainable Palm Oil. The principal criterion relevant to biodiversity is that new plantations have not been established on land of High Conservation Value (6). Many scientific and charitable groups contribute to bat monitoring and local education programmes that can help to reduce persecution and raise awareness of the natural assets of the land (3).

For further information on palm oil see:

• Greenpeace:
  www.greenpeace.org.uk/forests/palm-oil
• Fitzherbert, E.B., Struebig, M.J., Morel, A., Danielsen, F., Brühl, C.A., Donald, P.F. and Phalan, B. (2008) How will oil palm expansion affect biodiversity?. Trends in Ecology and Evolution, 23(10): 538-545. Available at:
  www.cbd.int/cms/ui/forums/attachment.aspx?id=37
• Friends of the Earth:
  www.foe.co.uk/campaigns/biodiversity/case_studies/palm_oil

Authenticated (03/10/08) by Matt Struebig, Queen Mary University of London.
http://webspace.qmul.ac.uk/mstruebig