We don’t yet know the precise role of bats in the Nipah outbreak
Most bats fly high/ Swooping only/ To take some insect on the wing; But there’s a bat I know/ Who flies so low/ He skims the floor; He does not enter at the window/ But flies in at the door. In his poem, ‘The Bat’, Ruskin Bond recounts the tale of a ‘crazy’ bat — albeit a fairly benign one — that made itself cosy at the foot of his bed on a lonely night in Mussoorie.
But ‘benign’ is certainly not the reputation bats have: superstition has them down as bad omens; science has proven they are carriers of disease — they are linked to the spread of SARS in China, MERS in Saudi Arabia, Ebola in Africa, and most recently debated as the possible cause of the Nipah outbreak in Kerala; the Indian Wildlife (Protection) Act, 1972, lists them largely as vermin. And blood-drinking Dracula hasn’t helped the creature’s cause.
The bat is something of a chimera: it has wings like a bird, the furry face of a mouse, it often flies zigzag or flits giddily like a moth. It belongs to the taxonomic order ‘Chiroptera’, derived aptly from the Greek words for ‘hand’ and ‘wing’.
I’ve been spooked by bats too, mostly because their movements are so inscrutable. While looking for a white barn owl perched on a lamp-post in Delhi one night, I was startled by a large flying fox that swooped down from the sky, it’s membranous wings translucent against the street light. I was convinced it was coming for my face, though of course, the frugivore was headed for a fig tree behind me.
India has no less than 128 species of bats — yet very little is known about their population status, their behaviour, or their role in the spread of zoonotic disease. Most species are listed as ‘data deficient’ in the IUCN Red List of Threatened Species. What we do know, however, is that many species are likely under enormous threat.
For instance, found in just one cave in a Karnataka village, the Kolar leaf-nosed bat is threatened by granite mining. Because of its very small range and a population of 200 or less, it has a high risk of extinction and is classified as critically endangered in the Red List. Salim Ali’s fruit bat, which also has a very small range in the tropical forests of the Western Ghats, is classified as endangered.
Research has shown that bat diversity has reduced in Delhi. Species once found in the crevasses of old buildings and in the Humayun’s Tomb complex are no longer found there. Humayun’s Tomb used to be known for its colony of Megaderma lyra, or the greater false vampire bat, distinguished by its long ears. And once found in several old buildings was the Tadarida aegyptiaca or the Egyptian free-tailed bat, which feeds on insects while in flight or while crawling on the ground with equal ease.
“Neither species is easily spotted in Delhi anymore,” says Sumit Dookia, Assistant Professor, University School of Environment Management, Guru Govind Singh Indraprastha University. Today, there are only four generalist bat species that remain in Delhi, he says: the fruit-eating Indian flying fox and the Leschenault’s rousette; and the insectivorous greater Asiatic yellow bat and the least pipistrelle bat.
Apart from habitat loss, bats are also prone to fatally colliding with wind turbine blades — and several wind power projects are coming up in India, particularly in Gujarat and in the Western Ghats. Greater mouse-tailed bats have been reportedly killed by wind turbines in Kutch. Concerns have also been raised about turbines impacting the movement or local migration of bat flocks.
Natural history has largely overlooked bats. As for the Wildlife Act, it names just two bat species for protection — Salim Ali’s fruit bat and Wroughton’s free-tailed bat. The Act does not name other bat species except the generic ‘fruit bats’, which are listed in Schedule V, where they find themselves in the company of ‘vermin’ such as common crows, mice and rats — species that can be legally removed or killed. Fortunately though, as bats are considered ‘wild’ animals, they must, at least in protected areas, remain protected and cannot be driven out, unlike feral dogs or buffaloes.
The only instance the animal got its due in terms of formal conservation was when Karnataka declared the Bhimgad forest a sanctuary to protect Wroughton’s free-tailed bat.
More than spooks
But much remains to be done. Bats, after all, provide huge ecological and economic services, says bat biologist Rohit Chakravarty. “Without insectivorous bats, farmers would lose billions to pest insects. Fruit bats are also important pollinators and seed dispersers in tropical forests. For example, the durian is mostly pollinated by bats.”
Chakravarty, like many others, believes that bats must be removed from the vermin list, because their populations could take time to recover from losses. “Bats are long-lived, slow-breeding species. A small 5 gm insectivorous bat is capable of living up to 30 years and gives birth to one or two pups a year. So, killing them indiscriminately can wipe out large chunks of their populations.”
Several organisations have recently asked for environmental impact assessments of wind energy projects, with a focus on impact on bats. Chakravarty adds, however, that we also need to find an urgent, cost-effective solution to mitigating fruit damage by fruit bats in orchards.
It is not yet clear if bats are responsible for the Nipah outbreak. While some bats have been tested — and found free of infection — those were insectivorous bats, not fruit bats. Further testing, and a greater understanding of the movement history of infected people, should bring clarity.
In his 1902 book The World of Animal Life, Fred Smith describes bats as ‘hand-winged animals’, ‘rendering good services to farmers’ by eating pests. It is a 117-year-old reminder that bats are in dire need of conservation focus; and that they deserve adjectives far better than ‘spooky’.
This first appeared in The Hindu, here.