Wildlife in Sri Lanka in January: What You Will See

Spinner Dolphin Common

Stenella longirostris

A small, slender dolphin that leaps clear of the sea and spins like a top in mid-air.

Where: Surface water offshore, on whale and dolphin boat trips. Best: November to April on the west and south coasts. Kalpitiya produces super-pods of many hundreds and sometimes over a thousand animals, which is the largest dolphin spectacle in South Asia.

Indo-Pacific Bottlenose Dolphin Regular Near Threatened

Tursiops aduncus

The classic bottlenose of warm coasts, sociable, clever and quick to ride a bow wave.

Where: Surface water offshore, on whale and dolphin boat trips. Best: December to April off the south and west, May to September off the east.

Blue Whale Occasional Endangered

Balaenoptera musculus

The largest animal that has ever lived, and off Sri Lanka a population that mostly does not migrate, which is why it can be seen almost year round.

Where: Deep water off the south and east coasts, close inshore where the shelf drops away. Best: Nov-Apr south, May-Sep east. Largely resident rather than migratory here, which is what makes it seeable almost year round.

False Killer Whale Occasional Near Threatened

Pseudorca crassidens

Has been recorded offering captured fish to divers and to other dolphins, apparently as a gift.

Where: Blue water beyond the continental shelf edge. Best: December to April off the south and west, May to September off the east.

Dugong Ultra rare Vulnerable

Dugong dugon

The gentle sea cow said to have inspired mermaid legends, grazing seagrass meadows in warm shallow seas.

Where: Seagrass beds in the Gulf of Mannar and Puttalam lagoon. Best: November to April on the west and south coasts. The Gulf of Mannar is the last Sri Lankan stronghold and the population is now very small. Most reports turn out to be dolphins.

Black-capped Kingfisher Occasional

Halcyon pileata

A striking mangrove kingfisher in black, white and deep purple-blue, a winter visitor to Thailand's coasts.

Where: Mangrove creeks, lagoon margins and shaded coastal channels. Best: October to April, on the northeast monsoon migration. A winter migrant here, and now assessed Vulnerable after a status change most guides have not caught up with.

Brown Booby Occasional

Sula leucogaster

Dives from twenty metres and hits the water at over sixty kilometres an hour, with air sacs in the skull absorbing the shock.

Where: Blue water beyond the shelf edge, often following boats. Best: December to April off the south and west. Usually seen from a whale watching boat rather than from land.

Greater Flamingo Occasional

Phoenicopterus roseus

Several thousand birds on the Bundala salt pans in a good winter, filtering brine shrimp upside down.

Where: Coastal salt pans and shallow saline lagoons. Best: Aug-Apr. A non breeding visitor from western India. Numbers swing hard between years with rainfall and salinity.

Great Knot Rare Endangered

Calidris tenuirostris

Flies from Siberia to Australia with a single refuelling stop, and losing that one mudflat has nearly finished the species.

Where: Tidal mudflats and salt pans, especially around Mannar and the Puttalam lagoon. Best: October to April. An Endangered long distance migrant and a scarce visitor here.

Pallid Harrier Rare Near Threatened

Circus macrourus

Quarters the grassland at head height on raised wings, tilting and rocking, hunting entirely by sound and surprise.

Where: Open grassland, salt pan margins, scrub and paddy. Best: Oct-Apr. Near Threatened, and a bird that has crossed from the Central Asian steppe to get here.

Olive Ridley Turtle Occasional Vulnerable

Lepidochelys olivacea

The smallest and most numerous sea turtle, famous elsewhere for mass nestings of thousands at once.

Where: Nesting on open sandy beaches, and feeding in shallow coastal water. Best: November to March, peaking December to January. Out of phase with the green turtle, so the season is the northeast monsoon rather than the spring.

Leatherback Turtle Rare Vulnerable

Dermochelys coriacea

The largest turtle on Earth, a jellyfish hunter that dives deeper than most whales and crosses whole oceans.

Where: Nesting on steep, high energy south coast beaches with deep water access. Best: January to June. Sri Lanka and the Andaman and Nicobar Islands hold the only leatherback nesting populations in South Asia.

Rhino-horned Lizard Rare Endangered

Ceratophora stoddartii

A cloud forest lizard with a curved horn on its nose, and when it is cornered it opens a bright orange mouth at you.

Where: Mossy montane cloud forest between about 1,200 m and 2,300 m. Best: January to March, early morning. Confined to the highest hills, and precisely the colour of the lichen it sits on.

Pygmy Lizard Very rare Endangered

Cophotis ceylanica

A moss mimic with a prehensile tail that grips like a chameleon's, and it gives birth to live young, which agamids are not supposed to do.

Where: Moss covered trunks and epiphyte clumps in montane cloud forest, 1,300 m to 2,200 m. Best: January to March. A moss mimic that does not move when approached. Guides find them, visitors do not.

Rough-horned Lizard Very rare Endangered

Ceratophora aspera

A horned lizard the length of a finger, living in the leaf litter of the lowland rainforest and shaped exactly like a dead leaf.

Where: Leaf litter on the floor of lowland wet zone rainforest below about 900 m. Best: January to early April and July to August. A four centimetre brown lizard in brown litter, and often in pairs.

Blue-green Chromis Common

Chromis viridis

A shimmer of living jewels above the coral, hundreds of tiny blue-green fish that vanish into the branches in a blink.

Where: Shallow reef flats and coral heads at Bar Reef and around Pigeon Island. Best: November to April on the west and south, May to September on the east.

Bluestreak Cleaner Wrasse Common

Labroides dimidiatus

A tiny striped wrasse that runs the reef's health clinic, picking parasites from fish that queue up and even open their mouths for it.

Where: Coral reef and boulder slopes on both coasts. Best: November to April on the west and south, May to September on the east. Find a cleaning station and stay still. Everything on the reef queues at one eventually.

Bluestripe Snapper Common

Lutjanus kasmira

A bright yellow snapper ruled with electric-blue lines, massing in dense, glowing schools around coral heads and wrecks.

Where: Shallow reef flats and coral heads at Bar Reef and around Pigeon Island. Best: November to April on the west and south, May to September on the east.

Humphead Wrasse (Napoleon Wrasse) Rare Endangered

Cheilinus undulatus

A giant, curious reef fish with thick lips and a bulging forehead, able to crunch prey that few other animals can eat.

Where: Reef edges and drop-offs, including the Trincomalee canyon rim. Best: November to April on the west and south, May to September on the east. Endangered and heavily fished across its range.

Thorny Seahorse Rare Vulnerable

Hippocampus histrix

Covered in long sharp spines and able to shift colour to match whatever it has wrapped its tail around.

Where: Sand and rubble patches between coral heads. Best: November to April on the west and south, May to September on the east.

Grey Reef Shark Occasional Endangered

Carcharhinus amblyrhynchos

The classic requiem shark of the drop-off, bold and inquisitive where currents sweep the reef.

Where: Deeper reef, wrecks and the Great and Little Basses reefs. Best: November to April on the west and south, May to September on the east.

Ocellated Eagle Ray Occasional Endangered

Aetobatus ocellatus

A dramatic ray that flies through open water on wings spangled with white spots, trailing a whip-like venomous tail.

Where: Reef edges and drop-offs, including the Trincomalee canyon rim. Best: November to April on the west and south, May to September on the east.

Bowmouth Guitarfish Very rare Critically Endangered

Rhina ancylostomus

Half shark, half ray, with ridges of thorns above the eyes that look like a set of eyebrows.

Where: Sand and rubble patches between coral heads. Best: November to April on the west and south, May to September on the east. Critically Endangered. Sri Lanka's wedgefish is Rhynchobatus djiddensis, the Indian Ocean species.

Giant Guitarfish Very rare Critically Endangered

Glaucostegus typus

A strange shark-ray hybrid in shape, part flattened ray at the front and part shark behind, and one of the most threatened fish in the sea.

Where: Sand and rubble patches between coral heads. Best: November to April on the west and south, May to September on the east. Critically Endangered. Sri Lanka's wedgefish is Rhynchobatus djiddensis, the Indian Ocean species.

Whitespotted Wedgefish Very rare Critically Endangered

Rhynchobatus australiae

Its fins are the single most valuable in the global shark fin trade, which is why it has all but disappeared.

Where: Sand and rubble patches between coral heads. Best: November to April on the west and south, May to September on the east. Critically Endangered. Sri Lanka's wedgefish is Rhynchobatus djiddensis, the Indian Ocean species.

Blue Dragon Nudibranch Regular

Pteraeolidia semperi

Steals stinging cells from the hydroids it eats and redeploys them, live and functional, in its own tentacles.

Where: Coral reef and boulder slopes on both coasts. Best: November to April on the west and south, May to September on the east.

Chromodoris Nudibranch Regular

Chromodoris species

A tiny sea slug in outrageous colours that borrows toxins from the sponges it eats and flaunts them as a warning.

Where: Coral reef and boulder slopes on both coasts. Best: November to April on the west and south, May to September on the east.

Small Giant Clam Regular

Tridacna maxima

The electric blue and green lips are not pigment for show. They are farming light, and the clam gets most of its food from algae living in its own flesh.

Where: Wedged into shallow coral and rock on reef flats. Best: November to April on the west, May to September on the east. The true giant clam does not reach Sri Lanka. This is the one you will actually see.

Varicose Phyllidia Regular

Phyllidia varicosa

Squeezes out a toxin strong enough to kill every fish in a bucket with it, which is why nothing on the reef will touch it.

Where: Coral reef and boulder slopes on both coasts. Best: November to April on the west and south, May to September on the east.

Table Coral Common Near Threatened

Acropora hyacinthus

Grows outward faster than it grows up, spreading a flat platform that shades out every competitor beneath it.

Where: Shallow reef flats and coral heads at Bar Reef and around Pigeon Island. Best: November to April on the west and south, May to September on the east. Both suffered severe bleaching mortality on Sri Lankan reefs in 1998 and again in 2016.

Blue Coral Regular Vulnerable

Heliopora coerulea

The only coral on earth with a blue skeleton, hidden under brown tissue until the animal dies.

Where: Shallow reef flats and coral heads at Bar Reef and around Pigeon Island. Best: November to April on the west and south, May to September on the east. The skeleton is genuinely blue. Break a piece and you can see it, so do not.

Anchor Coral Occasional Vulnerable

Euphyllia ancora

Every tentacle ends in a fat hammer-shaped tip, so the whole colony looks like a field of tiny anchors.

Where: Coral reef and boulder slopes on both coasts. Best: November to April on the west and south, May to September on the east.

Bubble Coral Occasional Near Threatened

Plerogyra sinuosa

Inflates itself into a cluster of grape-sized bubbles by day and deflates at night to put out stinging tentacles.

Where: Coral reef and boulder slopes on both coasts. Best: November to April on the west and south, May to September on the east.

Blue Sea Star Common

Linckia laevigata

An almost unreal cobalt blue starfish scattered across the shallows, able to regrow a whole body from a single lost arm.

Where: Shallow reef flats and coral heads at Bar Reef and around Pigeon Island. Best: November to April on the west and south, May to September on the east.

Cushion Star Common

Culcita novaeguineae

So swollen with age that the arms disappear entirely and it ends up looking like a pentagonal beanbag.

Where: Shallow reef flats and coral heads at Bar Reef and around Pigeon Island. Best: November to April on the west and south, May to September on the east.

Granulated Sea Star Common

Choriaster granulatus

Fat, pink and smooth as putty, it looks less like a starfish than a set of five bread rolls.

Where: Shallow reef flats and coral heads at Bar Reef and around Pigeon Island. Best: November to April on the west and south, May to September on the east.

Pineapple Sea Cucumber Regular Endangered

Thelenota ananas

A metre-long sea cucumber covered in star-shaped spikes, and one of the most valuable animals per kilo in Asian seafood.

Where: Sand and rubble patches between coral heads. Best: November to April on the west and south, May to September on the east. Sea cucumbers are fished hard in the Gulf of Mannar for the export trade.

Banded Coral Shrimp Regular

Stenopus hispidus

A candy-striped shrimp with impossibly long white antennae that it waves to advertise its parasite-cleaning service.

Where: Coral reef and boulder slopes on both coasts. Best: November to April on the west and south, May to September on the east.

Durban Dancing Shrimp Regular

Rhynchocinetes durbanensis

Packs into caves in the hundreds, and the whole mass sways together when a torch beam crosses them.

Where: Coral reef and boulder slopes on both coasts. Best: November to April on the west and south, May to September on the east.

White-spotted Hermit Crab Regular

Dardanus megistos

Bright red and dotted with white, and it will kill a living snail to take the shell it wants.

Where: Shallow reef flats and coral heads at Bar Reef and around Pigeon Island. Best: November to April on the west and south, May to September on the east.

Boxer Crab Occasional

Lybia tessellata

Carries a live sea anemone in each claw and waves them at threats, and if it loses one it tears the other in half to clone a replacement.

Where: Coral reef and boulder slopes on both coasts. Best: November to April on the west and south, May to September on the east.

Christmas Tree Worm Common

Spirobranchus giganteus

Pairs of tiny spiral trees in every colour, studding the coral and vanishing in a flash when a shadow passes.

Where: Shallow reef flats and coral heads at Bar Reef and around Pigeon Island. Best: November to April on the west and south, May to September on the east. Wave a hand near one and the whole colony vanishes at once.

Giant Barrel Sponge Regular

Xestospongia testudinaria

Filters tens of thousands of litres a day and can live for well over a century, which is why divers call them the redwoods of the reef.

Where: Deeper reef, wrecks and the Great and Little Basses reefs. Best: November to April on the west and south, May to September on the east.

Persian Carpet Flatworm Occasional

Pseudobiceros bedfordi

Two hermaphrodites fight by fencing with their reproductive organs, and the loser has to carry the eggs.

Where: Coral reef and boulder slopes on both coasts. Best: November to April on the west and south, May to September on the east.

Portuguese Man o' War Occasional

Physalia physalis

Not one animal but a colony of four kinds of specialised individual that cannot survive apart.

Where: Rocky shores, tide pools and the intertidal on both coasts. Best: November to April on the west and south coasts. Strandings come in on the monsoon wind. The sting works on the beach too.

Asian Elephant Common Endangered

Elephas maximus

The largest land animal in Asia, and a herd crossing open grassland at dusk moves over the ground faster than its size suggests.

Where: Dry zone parks, tank margins and the corridors between them. Best: Year round, best at the Gathering from July to October. Sri Lankan bulls are mostly tuskless, so a tusker here is a genuine rarity rather than the norm. The island holds around six thousand wild elephants, one of the largest Asian populations.

Toque Macaque Common Endangered

Macaca sinica

A small endemic monkey with a swirl of hair on the crown arranged like a cap, and the most studied primate on the island.

Where: Forest and forest edge from the dry zone to the highlands. Best: Year round. Endangered and endemic, and like macaques everywhere it becomes a problem where it is fed.

Purple-faced Langur Occasional Endangered

Semnopithecus vetulus

A shaggy black leaf monkey with white side whiskers, and the highland form is so hairy it is known as the bear monkey.

Where: Wet zone and montane forest canopy. Best: Year round. Endangered and endemic, and the lowland form has lost most of its forest.

Sri Lankan Leopard Occasional Endangered

Panthera pardus kotiya

The largest leopard subspecies in the world, and on this island it is the top predator, which changes how it behaves.

Where: Dry zone scrub forest, and at lower density in the hills and wet zone. Best: Year round. Endangered, perhaps eight hundred to a thousand animals. Top predator here, which is why it behaves so differently.

Sri Lanka Blue Magpie Occasional Vulnerable

Urocissa ornata

Cobalt and chestnut with a blood-red bill, and it comes to look at you rather than the other way round.

Where: Wet zone rainforest of the southwest; Sinharaja and Kitulgala. Best: Year round, best Jan-Apr. Confined to a small and shrinking band of the island, and unmistakable when you find it.

Serendib Scops Owl Very rare Endangered

Otus thilohoffmanni

Found by its call in 2001 and described in 2004, the first new bird species discovered in Sri Lanka for over a century.

Where: A handful of wet zone forest fragments. Best: Year round, calls at dusk. Endangered, tiny population, and only described in 2004.

Sri Lanka Whistling Thrush Very rare Endangered

Myophonus blighi

A dark highland thrush that sings from wet rock at first light and is gone by the time the mist lifts.

Where: Shaded fast-running streams in montane forest above 900 m. Best: Year round, first light. Endangered, with a population thought to be under a thousand mature birds.

White-faced Starling Very rare Endangered

Sturnornis albofrontatus

A canopy starling with a white face, confined to a shrinking scrap of rainforest and genuinely hard to catch up with.

Where: Canopy of undisturbed wet zone rainforest. Best: Year round. Endangered and one of the scarcest endemics.

Black-lipped Lizard Regular Endangered

Calotes nigrilabris

An Endangered endemic that you will see without trying, because it basks on the hedges at Horton Plains.

Where: Montane shrub, hedge and tree trunks above about 1,000 m. Best: Year round, sunny mornings. The easiest Endangered lizard on the island to photograph.

Hawksbill Turtle Occasional Critically Endangered

Eretmochelys imbricata

The reef's sponge specialist, its beautiful shell also the reason it was hunted to the edge.

Where: Coral reef, feeding on sponges; nesting on coarse sand pocket beaches and now very rare. Best: Reef season by coast; nesting almost nonexistent. Six nests out of 2,660 at Rekawa. This is a reef sighting, not a beach one.

Knuckles Pygmy Lizard Ultra rare Critically Endangered

Cophotis dumbara

Described in 2006, Critically Endangered within a year, and confined to one mountain range where it sits motionless on wet moss.

Where: Wet moss and lichen on montane cloud forest bark in one massif only. Best: Year round, and effectively unfindable without a specialist. Described in 2006 and Critically Endangered within a year. Here because it exists, not because you will see one.

Leaf-nesting Shrub Frog Occasional Endangered

Pseudophilautus femoralis

Every other shrub frog on the island buries its eggs in soil. This one glues them to the underside of a leaf, and finding that green clutch is easier than finding the frog.

Where: Montane forest of the central highlands. Best: Year round, night. Look for the eggs as well as the frog. A green clutch glued under a leaf is this species and nothing else.

Noellert's Toad Very rare Critically Endangered

Duttaphrynus noellerti

It moved from Endangered to Critically Endangered between assessments, which makes it the clearest single marker of what is happening to the lowland wet zone.

Where: Lowland rainforest of the southwest wet zone. Best: Year round, night. Critically Endangered and worsening. A conservation datapoint rather than a sighting.

Starry Shrub Frog Ultra rare Critically Endangered

Pseudophilautus stellatus

Described in 1853, declared extinct, then found alive after a hundred and fifty six years, in the canopy where nobody had thought to look.

Where: Cloud forest canopy in the Peak Wilderness Sanctuary, 1,540 m to 1,679 m. Best: Year round, and effectively unfindable. Lost for 156 years, then found ten metres up in the canopy where nobody had looked. Here as a record, not a target.

Fire Rasbora Occasional Endangered

Rasboroides vaterifloris

A shoal of these in a shaft of forest light is the reason the Victorians called it the pearly rasbora.

Where: Small, shaded, tea-coloured forest streams in the lowland wet zone. Best: Year round. Look for the shoal, not the fish. Movement in a shaft of light through the canopy is what gives them away.

Barred Danio Rare Endangered

Devario pathirana

Described only in 1990, and known from a handful of streams in one river basin.

Where: Clear, fast, shaded runs in the upper Nilwala basin only. Best: Year round. Its entire world range is a few square kilometres of hill stream in the far south.

Bandula Barb Ultra rare Critically Endangered

Pethia bandula

The entire world population of this fish lives in one stream, and you could walk its whole range in ten minutes.

Where: One short stretch of a single stream in the Kegalle district and nowhere else on earth. Best: Not applicable. We deliberately do not publish the locality. The population has been counted in the hundreds, collection is a listed threat, and visitor pressure on a stream this small is itself a risk. This is a species to know about, not to go and see.

No free photograph of the Bandula barb exists. The image shows Pethia aurea, a close relative in the same genus.

Largetooth Sawfish Ultra rare Critically Endangered

Pristis pristis

A seven metre ray with a chainsaw for a nose, and almost certainly gone from Thai waters.

Where: Lagoons, estuaries and mangrove creeks at Puttalam, Negombo and Kalametiya. Best: Year round. Almost certainly gone from Sri Lankan waters. Recorded here historically and listed so that the loss is on the page rather than quietly omitted.

Crimson Rose Common Near Threatened

Pachliopta hector

Flies slowly and in the open because it is poisonous and every predator on the island knows it.

Where: Dry zone scrub, garden edges, roadsides and park tracks countrywide. Best: Year round. Slow and low along tracks. One of the easiest butterflies on the island to watch properly.

Ceylon Rose Rare Critically Endangered

Pachliopta jophon

Critically Endangered, endemic, and confined to the shrinking rainforest of one corner of the island.

Where: Wet zone rainforest interior and its immediate edge, nowhere else. Best: Year round. Critically Endangered. If you think you have one outside wet zone forest, it is almost certainly a crimson rose.

Sri Lanka Relict Ant Ultra rare Critically Endangered

Aneuretus simoni

The only surviving species of an entire subfamily of ants, and it lives in the leaf litter of one island.

Where: Rotting twigs and leaf litter on the floor of undisturbed wet zone forest. Best: Year round. You will not identify this in the field and that is not the point. It is the last species of an entire subfamily of ants and it is under the leaf litter you are standing on.

Golden Orb-weaver Common

Nephila pilipes

A giant black-and-yellow spider spinning webs of golden silk strong enough to snare small birds.

Where: Huge golden webs slung across forest tracks and clearings countrywide. Best: Year round, largest females August to December. Known throughout Sri Lanka as the giant wood spider. The silk is strong enough that you feel the web before you see it.

Signature Spider Common

Argiope anasuja

Writes a bold zigzag across the middle of its own web, and nobody is entirely sure why.

Where: Webs slung in scrub, gardens and dry zone forest edge countrywide. Best: Year round. The zigzag in the web is the identification, and its purpose is still argued about.

Giant Forest Scorpion Occasional

Heterometrus swammerdami

Among the largest scorpions on earth, and its sting is milder than a bee's.

Where: Under logs and stones by day, out hunting on the ground after dark. Best: Year round, after dark. A UV torch finds them from several metres. It is the single most rewarding five pounds of kit for a night walk.

Sri Lanka Tree Snail Occasional

Acavus phoenix

A snail the size of a plum, banded like a boiled sweet, that lives its whole life in the canopy.

Where: On trunks and branches in wet zone forest, moving at night and after rain. Best: Year round, best just after heavy rain. A canopy animal. Scan trunks at head height and above, not the leaf litter.

Fiddler Crab Common

Austruca annulipes

The male's oversized claw is useless for feeding, so he has to do everything with the small one while waving the big one at females.

Where: Lagoons, estuaries and mangrove creeks at Puttalam, Negombo and Kalametiya. Best: Year round.

Giant Mud Crab Common

Scylla serrata

The claws can generate enough force to crush a large clam, and will take a finger off without much trouble.

Where: Lagoons, estuaries and mangrove creeks at Puttalam, Negombo and Kalametiya. Best: Year round.

Horn-eyed Ghost Crab Common

Ocypode ceratophthalmus

The fastest crab on earth, clocked at over two metres a second, and it growls at intruders from inside its burrow.

Where: Rocky shores, tide pools and the intertidal on both coasts. Best: Year round. The crab that sprints across the sand at Rekawa while you are waiting for a turtle.

Upside-down Jellyfish Occasional

Cassiopea andromeda

Lies on the seabed with its tentacles pointing at the sky, farming algae inside its own tissue like a coral.

Where: Lagoons, estuaries and mangrove creeks at Puttalam, Negombo and Kalametiya. Best: Year round.

Box Jellyfish Rare

Chironex indrasaksajiae

Has twenty four eyes, including four that form proper images, and it is the only animal in Thai waters that has killed swimmers.

Where: Rocky shores, tide pools and the intertidal on both coasts. Best: Year round. Medically serious. Stings are reported from Sri Lankan beaches, mostly in the wet months.

No free photograph of Chironex indrasaksajiae exists. The image shows the Australian box jellyfish, Chironex fleckeri, its close relative in the same genus.

Sloth Bear Rare Vulnerable

Melursus ursinus

A shaggy, long-clawed insect specialist that vacuums termites out of a mound loudly enough to hear from fifty metres.

Where: Dry zone forest and scrub. Best: Jun-Jul when palu fruit ripens. Vulnerable, unpredictable, and mostly nocturnal outside the fruiting season.

Sperm Whale Rare Vulnerable

Physeter macrocephalus

The deepest diving mammal on earth, hunting squid two kilometres down, and occasionally gathering off Sri Lanka in pods of hundreds.

Where: Deep water off the east and northeast coasts. Best: Mar-Aug. Unusually large aggregations have been recorded here, occasionally running into the hundreds.

Black-naped Tern Occasional

Sterna sumatrana

Almost pure white apart from a narrow black band across the back of the head, like a headphone cable.

Where: Offshore islets and reef edges, including around Pigeon Island. Best: May to September on the east.

Bridled Tern Occasional

Onychoprion anaethetus

Spends most of the year entirely at sea, feeding on fish driven to the surface by tuna hunting below.

Where: Offshore water and rocky islets, well away from the beach. Best: May to September.

Bengal Monitor Common

Varanus bengalensis

A dry-country monitor that climbs well, digs constantly and eats essentially anything smaller than itself.

Where: Dry zone scrub, forest, farmland, termite mounds and tree hollows below about 1,500 m. Best: February to September. Terrestrial, unlike the water monitor, and the two are constantly confused.

Indian Star Tortoise Occasional Vulnerable

Geochelone elegans

The most trafficked tortoise on earth, and the Sri Lankan animals are the biggest and the most boldly starred of the lot.

Where: Dry and arid zone thorn scrub, dune country and grassy clearings below about 270 m. Best: Best after rain, October to December and March to April. Most people miss them because they are scanning for large mammals.

Leaf-nosed Lizard Very rare Endangered

Ceratophora tennentii

An Endangered horned lizard that exists on one mountain range and nowhere else in the world.

Where: Submontane cloud forest and shaded stream forest, 760 m to 1,220 m. Best: February to April and August to September. Its entire world range is one mountain massif.

Climbing Perch Regular

Anabas testudineus

A fish that walks out of the water and hauls itself overland on its gill covers, sometimes for hours.

Where: Paddy, seasonal tanks, ditches and drying pools across the dry zone. Best: May to September as the tanks drop, and after the first rains. Called kavaiya locally. It breathes air and will walk overland between drying pools on its gill covers and fins, which is worth knowing before you dismiss a fish crossing a wet road.

Dogtooth Tuna Occasional

Gymnosarda unicolor

A heavy-shouldered blue-water hunter that materialises out of the deep at reef pinnacles to smash into bait schools.

Where: Blue water beyond the continental shelf edge. Best: May to September on the east coast.

Bumphead Parrotfish Rare Vulnerable

Bolbometopon muricatum

A hulking, bull-headed parrotfish that rams and bites living coral, turning reef rock into the white sand of tropical beaches.

Where: Reef edges and drop-offs, including the Trincomalee canyon rim. Best: May to September on the east coast. Large aggregations are largely gone from South Asian reefs.

Blacktip Reef Shark Common Vulnerable

Carcharhinus melanopterus

The neat little reef shark of the shallows, its black-tipped fins often cutting the surface over sun-lit sand flats.

Where: Shallow reef flats and coral heads at Bar Reef and around Pigeon Island. Best: May to September on the east coast. Pigeon Island's shallow inner reef is the single most reliable place in Sri Lanka to see a shark, in snorkelling depth.

Great Hammerhead Very rare Critically Endangered

Sphyrna mokarran

Uses the flat of its head to pin a stingray to the seabed, then bites chunks out of the wing.

Where: Deeper reef, wrecks and the Great and Little Basses reefs. Best: May to September on the east coast. Both are Critically Endangered and Sri Lankan waters have been fished hard for them.

Scalloped Hammerhead Very rare Critically Endangered

Sphyrna lewini

The head is a sensory antenna, packed with electroreceptors that can find a ray buried under sand.

Where: Deeper reef, wrecks and the Great and Little Basses reefs. Best: May to September on the east coast. Both are Critically Endangered and Sri Lankan waters have been fished hard for them.

Blue Tiger Common

Tirumala limniace

Migrates in drifting rivers of thousands, and roosts at night in trees hung solid with butterflies.

Where: Open forest, scrub and roadsides, sometimes in large aggregations. Best: February to April and October to December. Roosts communally in shaded gullies, sometimes hundreds together, which is worth stopping for if you find one.

Common Emigrant Common

Catopsilia pomona

The butterfly behind the name Samanala Kanda, Butterfly Mountain, and the mass movement that heads for it every year.

Where: Open country, scrub and roadsides countrywide, and in numbers on the move. Best: February to April for the migration. Samanala Kanda, Adam's Peak, means Butterfly Mountain, and this is the butterfly it is named for.