Sri Lanka’s Bats | Ordered Disorder

Though occupying barely 1% of the world's total landmass, Sri Lanka hosts well over 2% of the world's recognised bat species.   But are there 28 species here?  Or 29?  Or 37?  How exactly do you count bats?

Cryptology, fractals, even Einstein’s Theory of Relativity – they all pale into bashful insignificance when compared to bat taxology. Between the kingdom within which a bat might exist, and the species to which it is classed as belonging, there are at least eight levels of mind-numbing grouping that bat scientists, or chiropterologists as they prefer to be called, pin their descriptions to. Unwilling to rest there, many then spend entire careers reordering the species, family and even the genus of these miniature mammals. The more daring go much further and bestow new subspecies divisions with all the generosity of a pool's winner.

The net result is that this most tiny of all mammals has had - and continues to endure - more name changes than even the hapless city of Plovdiv in Bulgaria. This blameless city of some 350,000 souls, famous for its icon painting, has endured 11 name changes so far. Somewhat coincidentally, it is also renowned for its bats, which host over 20 species and regularly host Bat Nights to introduce its avian mammals to its two-legged ones.

Short of dusting the animals with poisonous radioactive dust and equipping them with a miniature Kalashnikov, there is little else science can really do to make them more unapproachable, which is a terrible shame because bats – like lichen, coral, or bees - are among the world’s best indicator species, those that tell you relatively how healthy or not the environment really is.

Chiropterologists aside, we ought to pay attention to what is going on in the bat world, for if what bats have to say is anything to go by, then we are in trouble. All around the world, bats are in decline. Facing a tsunami of pollution, habitat loss, climate change, and aggressive new farming techniques, bat numbers worldwide have plummeted, and the continued existence of almost one-third of their species is threatened. It is ironic that, in the face of such a burgeoning catastrophe, the number of identifiable bat species continues to grow – it is now over 1500.

The counting of bat species in Sri Lanka is an art still much in the making, but all the signs are that, notwithstanding the overall decline in numbers, the country bats way above its weight. Though occupying barely 1% of the world's total landmass, Sri Lanka hosts well over 2% of the world's recognised bat species.

Scientists are, of course, minded to disagree with one another most of the time; indeed, put just one Chiropterologist in a room by himself and you will foster dissent. This is especially true when it comes to nailing down the number of bat species that exist here. It was thought to be 28. Then 29. Several new bats were discovered. Older bats were reclassified. Today, the number appears to be 37, though like adolescents with mood swings, this can change in an instant and often does.

But whatever family, genus, species, or subspecies they belong to, they all share certain bat-like traits. They all fly, for example. Bats are, of course, the only mammals able to truly fly, angels excepted and are famous for roosting upside down from their feet, viewing the world like happy drunks, a propensity made worse by their inferior vision. They all enjoy ultrasonic sound, and with this gift of supercharged hearing, they navigate the world with expert dexterity. Most live in large colonies and are much given to hibernation, a habit that accounts for their exceptionally long lifespan; one bat was recorded as living 41 years. Less happily, many are enthusiastic carriers of disease, especially those best able to leap from animals to humans.

XS

The Extra Small Bats

Sri Lanka’s bats can best be divided into eight broad categories, the first of which are the tiny bats, the ones so extraordinarily petite that their bodies barely measure 2 to 3 centimetres. There are three bats in the XS range, the smallest being the Indian Pygmy Pipistrelle Bat, whose Latin name (mimus mimus) is all the guidance you really need to know relatively how tiny it is. Next up in size is the Painted Bat, sometimes known as the butterfly bat. Small though it is, the creature is also dazzlingly beautiful, with thick, bright-orange fur all over, its wings decorated with black pyramids set into orange lines, like stained-glass windows. Decidedly less glamorous is the rust brown Pungent Pipistrelle, common in SE Asia but rarely found in Sri Lanka. The more exacting scientists long ago declared its few sightings here to be avoidable mistakes. The third XS bat, Hardwicke's Forest Bat, is one of those wretched beasts whose existence has been especially tortured by name changes and reclassifications. The most recent occurrence was in 2018, when it was dragged out of one species and reallocated to another under the name The Malpas Bat. Unlike most other bats, Hardwicke's Forest Bat is something of a loner. It was named after the East India Company soldier, Major-General Thomas Hardwicke, a man as much noted for his love of natural history as for his determination to defeat Tipu Sultan in battles across India. Like many East India men, Hardwicke had a complicated domestic life, leaving behind five illegitimate children and two other daughters born to his Indian mistress.

S

Bats of Small Size

Eight bats populate Sri Lanka’s Small Bat category, their sizes averaging around 4 centimetres, with upper ranges for some of up to 6 centimetres. The Indian Pipistrelle stands out, despite its size, for its rampant fertility. Most bats give birth once a year – usually to a single pup. The Indian Pipistrelle, however, does this three times a year. Dull orange with a worrying tendency to beige, the Fulvus Roundleaf Bat follows bat reproductive norms more exactly, breeding in November, to produce a single pup who will take well over a year to gain sexual maturity.

Little is known about the third XS bat, the Sri Lankan Leaf-Nosed Bat, as it was only identified as a new endemic species in 2025, its existence until then having been clumsily conflated with other cousins and near-cousins. Its telltale giveaways were an extra-board nose, an unusual ear shape, and a marginally different set of tiny head bones.

The same sorry fate was to befall the Dekhan Leaf-Nosed Bat, which, until 2025, had been horribly confused with several other species to which it only had a nodding acquaintanceship. It is considered critically endangered, and most scientists believe it doesn’t actually exist in Sri Lanka at all. Most, that is, but not quite all. Such rarity does not haunt Schneider’s Leaf-nosed Bat, which lives in colonies of around 1000 mates in caves across Sri Lanka.

The Rufous Horseshoe Bat, beautifully orange though it is, remains one to be avoided, as it was responsible for the 2002–2004 SARS outbreak. Van Hasselt’s Mouse-Eared Bat was named for the great biologist Johan Conrad van Hasselt, whose wretched reputation was such that almost everyone who joined him on expeditions into the unknown died or returned with a terminal illness, himself included.

His little bat is unusual for its fondness for living alone near water. More social is Cantor's Leaf-Nosed Bat, named for a Danish zoologist more famous for having nailed the taxonomic complexities of Siamese fighting fish.

M

Bats of Medium Size

Four baths fill the medium-size bat category, though "medium" means little more than between 5 and 5.5 centimetres in body length at most. Of the four, the stand-out star is the Sri Lankan Woolly Bat, first described in 1932 and one of just a very few endemic bats on the island. This was a big year for the world, bats included. The First Tarzan film premiered in America, whilst in Germany, Adolf Hitler swapped his Austrian nationality for a more useful German one. None of this was ever likely to trouble the little Woolly Bat hanging out in his preferred mountain habitat, roosting in the curled fronts of banana leaves. His celebrity is such that he has even managed to withstand the wave of excitement caused in 2022 when a new medium-sized endemic bat was declared here  - Phillip’s Long-Fingered Bat, which, until more eagle-eyed observers got to work, was long thought to be a run-of-the-mill Eastern Bent-Winged Bat. Long-fingered too is the penultimate of the medium-sized bats - Schreiber's Long-Fingered Bat. It is, of course, notable for its extremely long fingers, which give rise to vast wings and a shape, when spotted hanging, like that of an outside Christmas decoration, albeit grey, unlike the Ceylon Bi-Coloured Leaf-Nosed Bat, which is blamelessly ordinary in every respect.

L

The Large Bats

An average body size of 6 centimetres may not seem significant to most people, but for bats, it is precisely the sort of size that is getting on for awesome. The eight bats in this category all average around 6 centimetres in body length, but some can grow much further, up to eight and a half centimetres. The Indian Pygmy Bat is more easily spotted than most due to its erratic flight, with slow, fluttering movements that resemble a small biplane about to crash. Little if anything really distinguishes The Lesser Yellow Bat; it is not even predominantly yellow. The Egyptian Free-Tailed Bat is marginally easier to determine due to its large, forward-pointing ears. Tickell's Bat, long thought extinct in Sri Lanka, was rediscovered very recently, though so little is known about it that it offers jaded biologists a blank canvas for their PhDs. The delightfully named Wrinkle-Lipped Free-Tailed Bat is much more of a celebrity, its flight pattern elegant and sure, and its unmissable upper lip engraved with long, deep wrinkles suggestive of boundless wisdom. Famous too, though in a somewhat darker way, is the Greater False Vampire Bat. Its huge ears immediately call it out from other bats, but it is its eager, carnivorous feeding habits that mainly characterise it. It has a highly developed hunting strategy that enables it to capture not just the insects most bats exist on but also other bats, small birds, rodents, and fish. Of the large bats, the Black-Beared Tomb Bat is easily the most sociable, living in tribes, or towns might be a better word, of up to 4,000.

XL

The Extra Large Bats

Just three bats populate the XL space, coming in at around seven centimetres in body length - though at least one of them has been known to grow to an astronomical 3 centimetres. The Lesser Woolly Horseshoe Bat stands out – not just because the female is larger than the males, but also because they frequently give birth to twins. Such implicit gender politics is inverted with the Lesser Dog-Faced Fruit Bat, a bat that really does look like a diminutive dog – albeit one in which the males are apt to form harems, attended by multiple doting females. The last of the XL bats is the mournfully named Long-Winged Tomb Bat. It is a proud territory marker, with a very prominent glandular sac in which it stores its scent, a rare cologne of saliva and urine, which is kept for such special occasions as marking territory or courtship.

2XL

The Double XL Bats

Of the six bats that occupy the double XL space, all keep to around 8 centimetres, though the Short-Nosed Fruit Bat has been known to add an extra 3 centimetres to this. Its preferred home is not a cave but rather a self-built dwelling woven from vines or meshed palm fronds into walls. This home-making fixation is one it shares with the Round-Eared Tube-Nosed Bat. The Ceylon Great Horse-Shoe Bat is altogether more traditional, preferring caves - though in the most detached of ways, as it prefers to live by itself or, at best, in pairs. A cave dweller too is the Large Leaf-Nosed Bat, which, for reasons that defeat even the most inventive pharmacists, is a celebrated ingredient in several local medicines. This does not seem to have troubled its existence, as it is classified as of least concern by environmentalists – unlike the beautiful, dark, and fast-flying Pouch-Bearing Sheath-Tailed Bat, which is now critically endangered. Extinction is not on the cards anytime soon for the last of the double XL bats, the Greater Asiatic Yellow Bat, perhaps in part because of the female's unusual ability to store sperm for delayed ovulation.

3XL

The Triple XL Bats

Four bats, ranging from 9 to 14 centimetres in body length, hold out in the triple XL category. The first of them, the deliciously named and coloured Chocolate Bat, was considered extinct on the island until it was rediscovered after an 87-year gap. Kelaart’s Pipistrelle, unremarkable in many ways, stands out due to the size of the bone in its penis. This bone, missing in humans, is present in all male bats, and the 8 mm length of Kelaart's penis bone is something to marvel at. A more modest piece of anatomy marks the appearance of the Ceylon False Vampire Bat. It has uncommonly large ears, beautifully marked with lines, as are its gossamer wings, the yellow veins standing out when they are spread wide. A troubled identity haunts the Ceylon Fruit Bat, with many scientists debating where it fits in the pecking order or whether it is a subspecies, and proposing to rename it Leschenault's Rousette.

4XL

The Mega Bat

One bat and one bat only holds out in the 4XL category – the Common Flying Fox. At 15 to 25 centimetres, it really is the T.Rex of the island’s bat world, with a wingspan of 1 ½ metres and a weight of 1.6 kilos. Nocturnal, fruit-eating, and curiously infecund, they are an unmistakable part of any skyline, especially around city parks, where they gather at dusk to hang from trees in infamous colonies. Although unlikely to turn suddenly into airborne artillery, they are best kept at a distance, harbouring as they do such a wealth of diseases as to make biological warfare warriors tremble with dread.

Robert Howerd, the dark fantasy poet, recalled bats “Whirling, wheeling into westward, / Fled they in their phantom flight; / Was it but a wing-beat music / Murmured through the star-gemmed night? / Or the singing of a ghost clan / Whispering of forgotten might?”

And sadly, he may well prove to be right, with bats continuing the existential retreat into oblivion. Unless, that is, we learn from the success of the Common Flying Fox, which stands out as the go-to standard for all the island’s bats, being remarkably successful in their ability to take on and flourish in a world so altered by humans. Think on this next time you see one in parks around Colombo, or, famously, in the banyan, fig, and tamarind trees of the Peradeniya Botanical Gardens near Kandy, getting ready at dusk to go out hunting.

That was a production written and recorded by David Swarbirck at The Ceylon Press, based in the jungle north of Kandy at The Flame Tree Estate & Hotel, and set up to tell the story of Sri Lanka.