The forest is home to 53 mammals, of which 27 are large mammals; duiker-sized and above, several are Central African species found nowhere else in East Africa. Forest elephant and forest buffalo are smaller versions of their savanna relatives. Hippos and crocodiles are found in the Semliki river while the forest is remarkably rich in primates.
Chimpanzee, black and white colobus, central African red colobus, blue monkey, red-tailed monkey, de Brazza’s monkey, vervet monkey, grey-cheeked mangabey, baboon, and Dent’s mona monkey are present. Nocturnal primates include potto and bush baby.
Birdlife is especially spectacular with 441 recorded species that represent 40% of Uganda’s total of 1007. 216 of these are forest species – 66% of the country’s forest birdlist – while the list is expanded by the riverine habitat and a fringe of grassland in the east of the park. There are numerous rarities.
46 Guinea-Congo biome species are found nowhere else in East Africa while another 35 can be seen in only 2-3 other places in Uganda. Five species are endemic to the Albertine Rift ecosystem.