Crocodiles, monitors and snakes

The mugger crocodile, also called the marsh crocodile, is the one you are most likely to see. It inhabits freshwater tanks, rivers, reservoirs and lagoons across the dry zone, and it is common in Yala, Wilpattu, Bundala and the ancient tanks of the Cultural Triangle. Adults typically reach two to three metres and they are frequently seen basking on banks or lying motionless in shallow water.

The saltwater crocodile is a different animal. It is the largest living reptile, reaching well over four metres, and in Sri Lanka it occurs mainly in coastal estuaries, lagoons and mangrove systems in the south-west and west, including the Nilwala river near Matara and the Bentota and Madu river systems. It is genuinely dangerous and responsible for fatal attacks in Sri Lanka.

Fatal attacks occur in Sri Lanka every year, and the pattern is consistent: people bathing, washing or fishing at the edge of estuaries and rivers where saltwater crocodiles are present. Visitors are rarely the victims, but visitors also rarely know which water is which.

The rules are simple. Do not swim in lagoons, estuaries, mangrove channels or rivers in the dry zone or south-west unless a local specifically confirms it is safe, and treat any warning sign as absolute. Stay well back from water edges in national parks. Do not dangle limbs from a boat. Be particularly careful at dawn and dusk, when crocodiles are most active, and never approach one on land for a photograph, as they can move very fast over short distances.

The water monitor is the animal most often mistaken for a crocodile by nervous visitors. It is a very large lizard, second only to the Komodo dragon in size, reaching well over two metres, with a long forked tongue and a heavy tail. It is common everywhere there is water, including in Colombo's parks and canals, where it lives happily alongside a city of hundreds of thousands.

It is entirely harmless to people and mostly a scavenger and opportunist. Do not corner one, as a cornered animal of that size can inflict a nasty bite and tail lash, but there is no reason to be frightened of one crossing a path. The land monitor, or Bengal monitor, is smaller, drier-habitat and also harmless.

Sri Lanka has around a hundred snake species and the overwhelming majority are harmless. A small number are medically significant, and these are the ones worth being able to name: Russell's viper, the Indian cobra, the common krait, the Sri Lankan krait, the saw-scaled viper, and the hump-nosed pit viper, which causes a large number of bites though usually less severe envenomation.

Sri Lanka has a high snakebite incidence by global standards, but the context matters enormously: the overwhelming majority of bites occur to agricultural workers in rural paddy and plantation settings, at night or during field work, often barefoot. Bites to visiting travellers are rare.

Wear closed shoes when walking in vegetation, long grass or plantation edges, and use a torch after dark on rural paths, because kraits in particular are nocturnal and account for many night-time bites to people walking barefoot. Do not put hands into holes, under logs or into dense undergrowth you cannot see into. Watch where you step around stone walls and ruins, which snakes use for shelter and warmth.

If someone is bitten: keep them calm and still, immobilise the limb, do not apply a tourniquet, do not cut or suck the wound, and get to a hospital immediately. Sri Lankan hospitals stock antivenom and treat snakebite routinely and competently. Photographing the snake from a safe distance helps identification, but do not attempt to catch or kill it.

Sri Lanka has a remarkable endemic reptile fauna, particularly among the agamid lizards. The hump-nosed lizard and the rhino-horned lizard of the wet zone rainforests are genuinely strange-looking animals found nowhere else, and Sinharaja and the Knuckles are the places to look. The green forest lizard is common and unmistakable.

Among snakes, the green pit viper and several endemic colubrids are worth seeing, and a night walk at Sinharaja with a guide is by far the best way to encounter reptiles and amphibians. The island also has a large endemic freshwater turtle and terrapin fauna, and five marine turtle species nest on its beaches.

Crocodiles are near-guaranteed on any Yala, Bundala or Wilpattu drive and on the Madu Ganga and Bentota river boat trips. Water monitors are unavoidable, including in Colombo. The wet zone endemic lizards need Sinharaja or the Knuckles and, ideally, a guide who knows where to look.

The best single experience is a guided night walk in the rainforest, where geckos, pit vipers, frogs and the endemic agamids are all findable within a couple of hours. It costs little, requires a torch and a guide, and is one of the most underrated wildlife activities in the country.