Bio Diversity

The vegetation of the park comprises dense forest, mostly abandoned plantations and secondary formations. Of the 460 plant species that have been recorded in the forest, 135 are species of tree and 11 are lianas. These include 9 endemic species. The forest features an emergent layer, a canopy and an understory. Because of the dense two upper layers, understory is not present everywhere in the sanctuary, especially in areas with the invasive Peru balsam tree, (Myroxylon balsamum) Mahogany trees, (Swietenia macrophylla) and Devil's Ivy, (see Invasive Species section below).

A great variety of species are found in the forest. Some common native tree and shrub species are: Acronychia pedunculata (Sinhalese: "Ankenda"), Artocarpus nobilis ("Wal Del"), Artocarpus heterophyllus ("Kos"), Caryota urens ("Kitul"), Aglaia elaeagnoidea ("Puwanga"), Bombax ceiba ("Katu imbul"), Canarium zeylanicum, Cinnamomum verum ("Kurundu", cinnamon), Ficus virens, Filicium decipiens ("Pihimbiya"), Goniothalamus gardneri, Haldina cordifolia, Hunteria zeylanica, Mallotus tetracoccus, Mesua ferrea ("Na", ”Iron-wood”), Michelia champaca ("Sapu"), Mangifera zeylanica ("Atamba"), Neoclitsea cassia ("Dawul Kurundu”, Wild Cinnamon), Glycosmis sp., Litsea quinqueflora, Micromelum minitum ("Wal Karapuncha"), Pavetta blanda, Psychotria nigra, Vitex pinnata ("Milla") and Walsura gardneri.

There are many vine and liana species growing in the Udawattakele forest, most notable is the giant creeper Entada rheedii ("Pus Wel"). Some other species are Anamirta cocculus ("Tittawel”), Diploclisia glaucescens, Hiptage bengalensis, Hypserpa nitida ("Niriwel"), Morinda umbellata ("Kiri-wel"), and Paramignya monophylla. The Udawatta Kele is probably the best place in Sri Lanka for seeing full-grown rattan palms, ''Calamus'' (palm), of which there are at least two species. Some of the climbing palms here are over 25 meters long, growing up and over trees. Elsewhere in Sri Lanka rattan palms are often cut down when young for making rattan, but in the Udawattakele they are well protected.

Orchid species, mostly epiphytic, include Cymbidium bicolor, Luisa teretifolia, Polystachya concreta, Thrixspermum pulchellum, Tropidia curculigoides and Vanda testacea.

The sanctuary also is home to many species of non-flowering plants, Pteridophytes, such as the large ferns growing on steep banks along the shady road on the eastern side of the hill ridge. 

The tree species Alstonia macrophylla, introduced from Southeast Asia, is a common pioneer in previously cleared areas but poses no great threat to biodiversity because seeds sprout only in sunny, open areas, and when the trees get large, native shrubs and trees grow beneath them to eventually take their place.

Udawatta Kele is a famous birdwatching site. About 80 avifaunal species have been recorded from the sanctuary. The endemic bird species are Layard's Parakeet (Psittacula calthropae), Yellow-fronted Barbet (Megalaima flavifrons), and Brown-capped Babbler Pellorneum fuscocapillus. The rare Three-toed Kingfisher Ceyx erythacus has been observed occasionally. Sri Lanka Myna, Golden-fronted Leafbird, Blue-winged Leafbird, Spotted Dove, Emerald Dove, Tickell's Blue Flycatcher, Crimson-fronted Barbet, Brown-headed Barbet and Black-backed Kingfisher are common in the forest. Red-faced Malkoha and Kashmir Flycatcher are two birds listed as threatened that can be found in Udawatta Kele. 

Despite the forest reserve being completely surrounded by the Kandy town and its suburbs, there are many kinds of mammals, most of which are nocturnal. Mammals that can be seen the sanctuary are the endemic Pale-fronted Toque Macaque (Macaca sinica aurifrons), Mouse deer (Moschiola meminna), Porcupine (Hysterix indica), Indian Muntjac, Boar, Asian Palm Civet, Golden Palm Civet, Small Indian Civet, Ruddy Mongoose, Indian Giant Flying Squirrel, Greater Bandicoot Rat, Dusky Palm Squirrel, Indian Pangolin, Greater False Vampire Bat, Slender loris and Indian Flying-fox.

Several kinds of reptiles also inhabit the forest: There are snakes such as the Common hump-nosed pit viper (Hypnale hypnale), Green vine snake (Ahaetulla nasuta), Green pit viper (Trimeresurus trigonocephalus), Banded kukri (Oligodon arnensis), Boie's rough-sided snake (Aspidura brachyorrhos) Sri Lanka Cat Snake (Boiga ceylonensis), Oriental Ratsnake (Ptyas mucosus) and Spectacled cobra (Naja naja). Lizards that can be seen include the Green Forest Lizard (Calotes calotes), Sri Lanka Kangaroo-lizard (Otocryptis wiegmanni) and the Whistling lizard (Calotes liolepis). There are also several species of skinks, geckos, frogs and toads. Some Sri Lanka wet zone butterflies are also present.

The forest reserve has suffered from encroachment by squatters and land grabbing by surrounding land owners, but the forest ecosystem is now mainly threatened by invasive, introduced plant species that increasingly crowd away native plant and tree species and the animals and insects that live on them. These invasive species have no natural enemies such as diseases or insects and animals that feed on them and therefore grow and multiply much more rapidly than in their native habitats. Three introduced species pose the biggest threat to the natural biodiversity of the Udawatta Kele forest: The highly invasive Peru balsam tree Myroxylon balsamum from South America is the first. Dense stands of thousands of young trees can be seen along the roads in the eastern and northern side of the forest. The Pothos or Devil's Ivy, Epipremnum aureum, creeper from the Salomon Islands is the second major threat. In the Northwestern and Western part of the reserve, around the royal pond and near the presidential palace and Temple of the Tooth, the creepers completely cover several hectares of the forest floor. They also climb high up tree trunks, with their large leaves blocking the light for other species underneath. The creepers are gradually spreading further to the east and south. Some years ago they were even planted on road banks elsewhere in the forest. Mahagoney, Swietenia macrophylla, a timber tree from South America, is also quite invasive and disrupts the forest's diverse ecology. The Glow Vine, Saritaea magnifica, from Brazil is another invasive species, and covers several trees near the royal pond and near the Maitri cave. In some areas Aglaoneama communatum, Philippine Evergreen, is covering the forest floor and road banks.