Bat Tracks

On the tracks of two Indian bat species: one found in abundance, the other most elusive

 
Published: Sunday 07 June 2015

Bat Tracks

-- The Indian Wildlife Protection Act of 1972 consigned bats to schedule V as 'vermin'. While the more glamorous animals -- elephants, rhinos, lions and tigers -- have received considerable attention from conservationists in the country, bats have been largely ignored in such discourses.

Bats are the only mammals capable of true flight. The 950 species of bats found worldwide are said to have originated from one of the oldest surviving species. One of the oldest fossils, Icaronycteris, is from the early Eocene era, dating back at least 50 million years. And this fossil hardly differs from the modern bat! These fascinating creatures of the night belong to the order Chiroptera, meaning 'hand-wing'. Chiroptera has two suborders, Megachiroptera and Microchiroptera with 17 families and 177 genera.

Bats belonging to the suborder Microchiroptera are the microbats or insect-eating bats. They have small eyes and large ears, and produce ultrasound over 15 kHz, which human ears are unable to catch. They rely on echolocation for navigation and to catch insects. The suborder Megachiroptera consists of the megabats or fruit-eating bats. These bats have large, keen eyes, an acute sense of smell and small ears as compared to the size of their bodies. In general, Megachiroptera do not produce ultrasound; however, those belonging to the genus Rousettus have a primitive echolocation system. They make an audible clicking sound through their mouths.

Tropical fruit bats play a significant role in rainforestecosystems. Pollination of flowers, dispersal of seeds of trees, shrubs and climbers are all part of thier function in the ecosystem. Besides, bat droppings in the caves they occupy support adelicate ecosystem composed of unusual organisms.

India is one among the 25 mega-biodiversity hotspots that harbour the richest and most highly endangered eco-regions of the world. India is home to about a hundred species of bats, including 12 fruit bats, such as the fulvous fruit bat Rousettus leschenaulti, Indian flying fox Pteropus giganteus, Nicobar flying fox P faunulus, island flying fox P hypomelanus, Blyth's flying fox P melanotus, short-nosed fruit bat Cynopterus sphinx, lesser dog-faced fruit bat C brachyotis, Ratanaworabhan's fruit bat Megaerops niphanae, Salim Ali's fruit bat Latidens salimalii, Blanford's fruit bat Sphaerias blanfordi, dawn bat Eonycteris spelaea, and hill long-tongued fruit bat Macroglossus sobrinus. Sadly, though, data on the conservation status, population density, and ecology of many of these species is limited due to lack of field studies.

Not too long back, I conducted surveys in the south Indian state of Tamil Nadu. I was focussing my attention on two species in particular: the common Indian flying fox, and the much lesser-known Salim Ali's fruit bat. Although I covered about 720 sq km in three districts -- Nagai, Thanjavur and Thiruvarur -- I came across only nine colonies of the Indian flying fox. The size of the colonies varied hugely, some with about a 100 bats, others with over 1,200 bats. I monitored two colonies near the town of Sirkali for 12 months. Due to intensive hunting, the population in these colonies dropped from 1,000 to 700 in one, and 650 to 450 in the other.

Although people squirm at the very mention of the word 'bat', bats are rather clean animals, and groom frequently. The myth that all bats carry the rabies virus persists. However, statistics say that only 0.5 per cent of bats contract rabies. And bats, almost as a rule, only bite in self-defence. They pose no threat to people. Worryingly, being one of the slowest reproducing mammals of their size -- bats produce one young a year -- bats are extremely vulnerable to extinction. That these gentle, beneficial creatures have been widely misunderstood and neglected further adds to the danger.

With no protected natural forests suitable to sustain them, a large number of the flying fox colonies are located in unprotected agricultural land in villages. The flying fox prefer to roost in large Ficus benghalensis trees, which are located in sacred groves, and protected by the villagers. However, the very same bats become fair game when once they leave their roost to forage for food. Within a mere two months, I saw hunters selling 46 bats in the local markets.

These giant bats weigh about a kilogram, and their meat is considered a delicacy. There is also the belief that bat meat is capable of curing asthma. The population decline in the two colonies I was studying is an indication that hunting is beginning to take its toll on one of the largest bats in India. If this unscrupulous hunting continues, these intriguing bats will become locally extinct in many villages. There are widely reported instances of the drastic decline in population, even extinction, of certain species of fruit bats, due to hunting in Southeast Asia and the Pacific Islands.

Salim Ali's fruit bats are far more elusive than the flying fox that I spent about a year with. A specimen of this species was first collected from the High Wavy mountain range in Tamil Nadu during 1948. British naturalist Angus Hutton had then mistakenly identified it as the short-nosed fruit bat. In 1970, well-known mammalogist Kitti Thonglongya re-examined the specimen, and discovered that it represents a new species in a new genus endemic to south India. This species was then named Latidens salimalii to honour India's ornithology legend. This bat entered the Guinness Book of World Records (1993) as one of the three rarest bats of the world. The other two are the small-toothed fruit bat (Neopteryx frosti) from Sulawesi and a hipposiderid bat (Paracoelops megalotis) from Vietnam.

I observed these bats in a cave in the rainforest near a coffee and cardamom estate adjacent to the Megamalai forest reserve, at an altitude of about 1,000-1,175 metres. I counted about 250 Salim Ali fruit bats when they emerged from their cave at dusk. I saw some of them plucking forest fruits and carrying them back into the caves, so they could eat it there.

In the past, estate workers killed these bats, as well Nilgiri langurs and lion-tailed macaques for food. One of the major reasons for this is the popular local belief that these rainforest mammals have medicinal value and cure diseases, including respiratory illnesses. The last few years have seen a change, though. Owners and workers have realised the importance of these rare species and have vowed not to disturb them. This is an especially significant fact in view of the fact that these bats live on private estates. They are, therefore, not covered by any real legal protection. The future, indeed the very survival, of these species depends on the estate workers' goodwill.

Part of the antipathy towards bats is owing to the fact that these bats eat fruits, and thus harm the output of the fruit industry. Although there are no authenticated scientific reports available on the extent of damage caused by fruit bats to cash crops in India, it does appear that such damage is minimal. More so, in comparison to the damage caused by other animals. Reports indicate that elephants and wild boar cause extensive damage to crops in south India. The Hanuman langur, bonnet macaque, porcupine, gaur, barking deer, mouse deer, black-napped hare, Malabar giant squirrel and pea fowl are all believed to cause rather extensive damage to crops.

Bat species in India are delicately balanced on the survival scale. Attitudes towards bats, myths about them, recklesshunting, disturbance of their natural habitat and lack of legal protection are all prodding bats away from a true chance atsurvival. A few simple steps could change this trend. First,educate people about bats. We could tell others about the role of bats in the ecosystem, dispel myths about them and fear of them, and speak of the importance of bats for biodiversity. Secondly, we could plan bat conservation projects, and try to build bat roosting sites in our area. There is so little known about the population status of so many species of bats that one could start a local 'bat-watching' society. Thirdly, we could write to our local legislators and parliamentarians and demand legal protection for bats. The Wildlife Protection Act of India evidently needs revision to include protection to all species of fruit bats, and other selected insectivorous bats. In short, act before it's too late.

The author teaches biology at Sun Yat-sen University, Taiwan, and is the author of 'Facts on bats: an introduction to the bats of Tamil Nadu'. He is reachable at agoram@mail.nsysu.edu.tw

Subscribe to Weekly Newsletter :

Comments are moderated and will be published only after the site moderator’s approval. Please use a genuine email ID and provide your name. Selected comments may also be used in the ‘Letters’ section of the Down To Earth print edition.