31 species of mammals have been recorded in the Knuckles wilderness, four of which are endemic and nine of which are nationally endangered. Some of the common species include Wild Buffalo, Wildboar, Black-Naped Hare, Jackal, Toque Macaque and Purple-faced Leaf Monkey (both these primates are endemic to Sri Lanka). Other mammals recorded include Leopard, Fishing Cat, Sambar, Mouse Deer and Elephants.
The Knuckles forest region has a rich composition of birdlife and has recorded over 130 species of birds. Over 10 migrant species are also found here. Of the total recorded species 20 are nationally endangered. Some of the endemics seen here include the Yellow-eared Bulbul, the elusive Sri Lankan Whistling Thrush, Sri Lankan Spot-wing Thrush, Yellow-fronted Barbet, Jungle fowl, Sri Lankan Super fowl, Sri Lankan Wood Pigeon, Sri Lankan Green Pigeon, Sri Lankan Hanging Parrot, Layard’s Parakeets, Brown-capped Babbler, Crimson-backed Woodpecker, Sri Lankan Woodshrike, Sri Lankan Dull-blue Flycatcher, Sri Lankan Myna, Bush Warbler and the Sri Lankan White-eye. Some of the migrants include Indian Pitta, Common Sandpiper, Gray & Forest Wagtails, Brown Shrike, Indian Blue Chat, Greenish Warbler, Large-billed Leaf Warbler, Brown-breasted Flycatcher, Asian Paradise Flycatchers and the endangered Kashmir Flycatcher.