The site, in the far north of the country, comprises the Nouabalé–Ndoki National Park sensu stricto (386,600 ha) plus some of the peripheral zone from its western border, the Ndoki river, to Bomassa and the immediate surroundings, including sandbars on the Sangha river, south to the village of Bounda and north to the international border with the Central African Republic, where it is contiguous with Dzanga–Ndoki National Park (CF008). The park contains 3,866 km² of undisturbed forest within the basin of the Nouabalé and Ndoki rivers, mainly between 340–400 m. The forest is of three types: swamp-forest along the main rivers, closed-canopy monodominant Gilbertiodendron dewevrei forest (often in narrow strips bordering the swamp-forest) and dryland forest, by far the most extensive. The latter is semi-evergreen with an open, mixed canopy (Sterculiaceae and Ulmaceae are important) and the understorey is usually very dense and dominated by Marantaceae and Zingiberaceae. This Sterculiaceae/Ulmaceae forest-type is characteristic of the northern fringes of the Guineo–Congolian forest block. There is also some secondary forest around Bomassa camp (the park headquarters) and village; human impact in the buffer zone is minimal today. Most of the peripheral zone to the west and south of the park has been logged once, at an intensity of about one tree per hectare. Finally, there are some small natural clearings in the forest in marshy depressions dominated by various types of herbaceous vegetation, including Cyperaceae swamps, locally called ‘bai’.
See Box and Table 2 for key species. So far, 314 species have been recorded, of which c.260 are proven or suspected breeders. The potential list (excluding vagrants) should be nearer 330. Species of special interest include Glaucidium capense (not uncommon in semi-evergreen forest with an open canopy), the little-known or relatively rare Bostrychia olivacea, Otus icterorhynchus, three species of forest nightjars (Caprimulgus batesi, C. binotatus and one yet to be identified), Phoeniculus castaneiceps, Melignomon zenkeri, Ploceus preussi and P. dorsomaculatus. Caprimulgus binotatus and C. sp. hold non-overlapping territories in semi-evergreen forest; the voice of the latter is identical to that of a forest nightjar taped in 1996 in the Itombwe mountains of eastern DR Congo (CD014) whence the only known specimen of C. prigoginei has been collected, thus it will more likely turn out to be C. prigoginei than a new species. Ploceus albinucha, a species of the northern fringes of the Guineo–Congolian forest block, may not occur much further south in Congo. Spermophaga poliogenys is probably near the western limit of its range. Stiphrornis sanghensis has been described as a new species from the adjacent Dzanga–Ndoki National Park in Central African Republic (site CF008). However, independant field research there, in Congo, and in neighbouring Cameroon, suggests it is no more than a subspecies of the widespread S. erythrothorax, and it is treated as such here, pending further evidence. This yellow-bellied form is quite common in Nouabalé–Ndoki. Gallinago media has been recorded, but its local status is unknown; Falco naumanni can be no more than a vagrant.
Non-bird biodiversity: The park was initially designated to protect the rich mammal fauna of the area, including Gorilla gorilla (EN), Pan troglodytes (EN), Procolobus (badius) oustaleti (LR/nt), Loxodonta africana (EN) and Tragelaphus euryceros (LR/nt).
BirdLife International (2019) Important Bird Areas factsheet: Nouabalé-Ndoki National Park complex. Downloaded from http://www.birdlife.org on 24/04/2019.