Sinharaja Forest Reserve is Sri Lanka's last largely undisturbed lowland rainforest, a strip of hilly wet-zone forest in the island's south-west whose UNESCO World Heritage property covers 88.64 km². It was established as a reserve in April 1978, is one of Sri Lanka's four UNESCO biosphere reserves, and was inscribed as a natural World Heritage Site in 1988 under criteria ix and x, for its living ecosystems and its biodiversity. About 60% of the reserve lies in Ratnapura District, with roughly 20% each in Galle and Kalutara districts, and it spreads across most of the Kalu Ganga basin and a small part of the northern Gin Ganga basin. More than 60% of its trees are endemic to Sri Lanka, and it is credited with 19 of the 20 bird species the island was once recognised as having to itself. Its wildlife, more than any single landmark, is the reason people come.
Dipterocarp Canopy of the Kudawa and Morningside Ridges
The forest is built by trees found almost nowhere else. Sri Lanka's south-western rainforests hold 58 species of dipterocarp, the tall, resin-rich family whose best-known member is called hora in Sinhala, and all but one are found only in these forests, including two endemic genera, Doona and Stemonoporus. Two plant communities dominate the lowland rainforests of the south-west, and both occur in Sinharaja. The Dipterocarpus community, led by Dipterocarpus zeylanicus and Dipterocarpus hispidus, fills the valleys and lower slopes. D. zeylanicus grows 40 to 45 m tall with a trunk 4 to 6 m around, and its oleoresin-rich timber has long been used for railway sleepers, beams and other heavy work.
The second community, the Mesua–Doona forest (na-doona in Sinhala), takes over on ridges. It mixes Mesua ferrea, the na tree that is Sri Lanka's national tree, with several endemic Doona species, Cullenia rosayroana and Palaquium petiolare. The Kudawa sector, about 460 m above sea level, is classed as this Mesua–Doona type, while the Morningside sector, at about 1,040 m, carries forest transitional between lowland wet-evergreen and montane forest. Virgin forest of this kind has four layers: a main canopy at 30 to 40 m, a sub-canopy at 15 to 30 m, an understorey of 5 to 15 m and a sparse shrub layer, with emergent trees reaching 45 m. Sri Lanka was part of Gondwana until the Cretaceous, and many ancient Gondwanan plant and animal groups survive in these forests.
Nineteen Endemic Birds and the Sinharaja Bird Waves
Birdwatchers come for the endemics, and the count has changed as taxonomists have split species. Sri Lanka's list settled at about 21 endemics after 1977 and rose to 23 in 1990; the accepted figure is now 35, the latest addition being the Sri Lanka shama, split from the white-rumped shama in 2022. The figure of 19 out of 20 belongs to the older count, and the whole of this lowland forest ecoregion lies inside BirdLife International's Sri Lanka Endemic Bird Area.
The Sri Lanka blue magpie measures 42 to 47 cm, bright blue with a chestnut head and wings and a red bill, legs and eye ring. It needs tall, undisturbed wet-zone forest, from below 150 m to 2,150 m, and is listed as Vulnerable because that forest has been fragmented; surveys between 2004 and 2006 found it in only 38 forest patches across six forest complexes. Unusually for a forest specialist, it is attracted rather than scared off by moderate numbers of visitors, and groups have often been seen waiting near trails expecting to be fed. Researchers have identified 13 common call types, including mimicry of raptors.
The red-faced malkoha, a 46 cm cuckoo with a green bill and a red patch around the eye, is largely confined to Sinharaja and the forest around it in the wet zone. It is found in nearly half of the mixed-species feeding flocks in the Sinharaja area, usually towards the front. These flocks, sometimes called bird waves, are Sinharaja's signature spectacle: insect-eating birds of many species moving through the canopy together, and in Sri Lanka the vocal mimicry of the greater racket-tailed drongo may help to start them. The green-billed coucal, a shy purple-black cuckoo 43 cm long with a light green bill, is another wet-zone endemic listed as Vulnerable.
The most recent find came from the reserve itself. The ornithologist Deepal Warakagoda first heard an unfamiliar poo-ooo call in the Kitulgala rainforest, and on 23 January 2001 he finally saw the bird in Sinharaja. Described in 2004 as the Serendib scops owl, it was the first new bird found in Sri Lanka since the Sri Lanka whistling thrush in 1868. A 16.5 cm reddish-brown owl without ear tufts, it was known from only about 80 individuals at the end of January 2006.
Purple-Faced Langurs, Leopards and the Last Two Rainforest Elephants
Sinharaja's mammal list reads like a roll-call of Sri Lankan endemics and subspecies: the purple-faced langur, toque macaque, red slender loris, golden palm civet, Sri Lankan spotted chevrotain, Sri Lankan leopard, sambar deer of the local subspecies and the Sri Lankan elephant. The purple-faced langur is a shy, long-tailed leaf monkey with a dark face and white sideburns, and males measure 50 to 67 cm in the body with a tail of up to 85 cm. It was once common even in suburban Colombo and the villages of the wet zone; it is now placed in the genus Semnopithecus after DNA showed it is closer to the grey langurs.
The Sri Lankan leopard is the island's top predator and survives in every habitat type, including these wet forests. It was described as a subspecies in 1956 and has been listed as Vulnerable since 2020, with fewer than 800 mature individuals estimated. Elephants are a different story. Most of Sri Lanka's elephants now live in the dry zone of the north, east and south-east, and a 2023 study of human-elephant conflict around the reserve reported that Sinharaja supports the last two remaining lowland rainforest elephants in the country.
Small mammals are still being discovered. The Sinharaja shrew (Crocidura hikmiya), named from the Sinhala word for shrew, was described from two places in the reserve, the Kudawa sector at 460 m and the Morningside estate at 1,040 m. At Kudawa it was found in secondary forest that regrew after logging in the 1970s. Later records came from near Peak Wilderness Sanctuary and Kanneliya Forest Reserve, but the species is still known from only about three distinct locations, so a single threat to Sinharaja could hit most of its known range.
Pit Vipers, Kangaroo Lizards and the Sri Lankan Birdwing
The forest floor and understorey belong to reptiles, amphibians and insects. The Sri Lankan green pit viper (Craspedocephalus trigonocephalus), locally pala polonga, is an endemic, sluggish, mostly nocturnal snake that rests on low shrubs in the morning and holds on to branches with its tail. Females grow up to 130 cm, far larger than males, and wet-zone animals show the boldest black patterning. It occurs from about 153 to 1,800 m. The hump-nosed viper, a smaller venomous pit viper of Sri Lanka and south-western India, is also part of the reserve's fauna, and leeches are among the invertebrates walkers meet on the trails.
In the leaf litter lives the brown-patched kangaroo lizard (Otocryptis wiegmanni), an endemic agamid of wet-zone forests that receive more than 2,000 mm of rain a year, found up to 1,300 m. Adults are only about 7 cm from snout to vent but carry a 15 cm tail, and males have a maroon patch on the throat. Sri Lanka's amphibian diversity is still being documented: the island has more than 120 known species, over 90 of them endemic, and tree frogs make up a large share of those found in Sinharaja. Above them flies the Sri Lankan birdwing (Troides darsius), the island's largest butterfly and its national butterfly, with a wingspan of 165 to 175 mm, black forewings and yellow patches on the hindwings. Its caterpillars feed on Aristolochia vines, and deforestation is the main threat to it.
From 1978 Reserve to 1988 World Heritage: Guarding 88.64 km²
The species above depend on a forest that is small and surrounded. Sri Lanka's lowland rainforests cover about 124,341 ha in total, only 2.14% of the island's land area, and Sinharaja is one of fourteen forests, from Kanneliya to Kottawa, listed as representing the ecoregion. Dozens of villages line its boundary, and residents collect medicinal plants, fruit, nuts, mushrooms, honey and a sweet sap tapped from the Caryota palm. Sri Lanka's forest reserves, including those defined under the National Heritage Wilderness Area Act of 1988, are run by the Department of Forest Conservation.
Pressure has never gone away. Logging in the 1970s left the regrown secondary forest where the Sinharaja shrew was later found. In 2013, UNESCO asked Sri Lanka to stop the widening of an old road linking Lankagama to Deniyaya along a 1 km stretch of forest inside the protected area, after a complaint from the Centre for Environmental and Nature Studies. In March 2021, the environmentalist Bhagya Abeyratne drew widespread media attention to clearing inside the reserve. Martin Wijesinghe, who acted as the forest's unofficial guardian from the 1950s until his death in 2021, is remembered as one of the people most closely tied to the reserve. On the other side of the ledger, a 2019 decision reported by Mongabay set out to enlarge the protected forest to about 36,000 ha, roughly four times its size.
Visitors enter through four gates: Weddagala in the north-west, Rakwana in the north-east, Neluwa in the south-west and Deniyaya–Mederipitiya in the south-east, and every group must walk with a licensed guide. Heavy rain shapes any visit, and the two monsoons decide which months suit a trip, as our breakdown of the best time to visit Sri Lanka explains. You can also compare this lowland forest with the cloud forest and grassland of the island's highest plateau in our guide to Horton Plains.