Bicoloured leaf-nosed bat (Hipposideros bicolor)
|Synonyms:||Hipposideros erigens, Hipposideros javanicus|
|Size||Average forearm length: 45.5 mm (2)|
Average wingspan: 282 mm (2)
Average weight: 8.1 g (2)
Classified as Least Concern (LC) on the IUCN Red List (1).
The bicoloured leaf-nosed bat can be a vivid orange colour as a result of the bleaching fumes that collect in a cave atmosphere, whereas those individuals that live in well-ventilated caves may be light brown in colour. The bats have pointed ears and a small, pink noseleaf, (a flap of skin on the nose), with a straight membrane between the nostrils (internarial membrane). The noseleaf is used to focus echolocation calls and the ears collect the returning echoes, allowing the bat to build up a picture of its surroundings (3).
This species has a large range in Southeast Asia and Australia, occurring in southern Thailand, Peninsular Malaysia, Sumatra, Java, Borneo, the Philippines, Sumbawa, Seralu, Sumba, Savu, Roti, Timor Islands, and adjacent small islands (4) (5).
There are four subspecies of the bicoloured leaf-nosed bat: Hipposideros bicolor atrox is found from southern Thailand to Sumatra; Hipposideros bicolor bicolor is found on Borneo and Java to the Lesser Sunda Islands; Hipposideros bicolor major is found on Nias and Enggano Islands (4) (6); and Hipposideros bicolor erigens is found in the Philippines (4).
An inhabitant of rainforests, the bicoloured leaf-nosed bat roosts in caves, caverns and temple interiors, in groups of up to 150 individuals. The roost must have a constant temperature that is cooler than the surroundings by several degrees, as well as being in darkness and having a high humidity (7).
This insectivorous bat feeds amongst the vegetation of lower levels of the rainforest, where it navigates around the branches and hunts for its prey using echolocation. It emits ultrasonic shouts from its complex noseleaf and listens for the returning echo. This even enables the bat to distinguish between different species of fly according to their size and wingbeat (3).
Research is currently being carried out to elucidate the presence of two apparently different species in Peninsular Malaysia, based on echolocation frequency and size. Despite nearly identical appearances, the bicoloured leaf-nosed bat has been found to fall into two distinct groups. One has an echolocation call of between 127.0 to 134.4 kilohertz, with forearm and tibia lengths of more than 45 millimetres and 20 millimetres, respectively (10), and a lower weight, and shorter, wider wings with more rounded wingtips (9). These factors indicate that this bat may be more suited to hunting in cluttered space as it has greater agility in flight (9). The other has an echolocation call of 138.0 to 144.0 kilohertz and forearm and tibia lengths less than 43 millimetres and 19 millimetres, respectively (10).
The bicoloured leaf-nosed bat gives birth to one pup each year, which it must locate in the crowded roost after foraging trips. The mother does this by calling to her pup and listening for its reply. Once nearby, she uses pheromones to identify it. She will suckle it for some weeks before it learns to fly and forage alone. Bicoloured leaf-nosed bats become sexually mature at one year old (3).
The greatest threat to the bicoloured leaf-nosed bat is habitat loss and degradation. Deforestation continues at a steady rate for conversion to agricultural land and building communities. A particular concern is the rapid increase in land devoted to growing oil palm which has resulted in extensive loss of primary forest. Together, Malaysia and Indonesia export 88 percent of the world’s palm oil, for use in products such as margarine, lipstick and detergent. Persecution of bats is also a threat, despite the contribution of many bats in the control of insect crop pests (8).
Deforestation of primary forest, particularly for oil palm plantations, and especially within protected areas, is an issue of major concern and one that relies on both governmental action and consumer concern. Some large retailers have agreed, in collaboration with the WWF, to source products containing palm oil from plantations that are not on deforested land (8). 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).
Authenticated (04/02/08) by Dr. Paul Bates, Harrison Institute (
http://www.harrison-institute.org) and Bounsavane Douangbubpha, University of Laos.
- Echolocation: detecting objects by reflected sound. Used for orientation and detecting and locating prey by bats and cetacea (whales and dolphins).
- Insectivorous: insect-eating.
- Pheromone: a chemical produced by an animal, which stimulates a behavioural or physiological response by another member of the same species.
- Primary forest: forest that has remained undisturbed for a long time and has reached a mature condition.
- Subspecies: A population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.
- Tibia: in insects, the long (often narrow) segment of the leg that attaches to the femora or femur at the end closest to the body.In tetrapods (vertebrates with 4 limbs), the forward facing long bone in the lower hind limb (the shin bone).
- Ultrasound: sounds that are above the range of human hearing.
IUCN Red List (December, 2009)