The site lies to the west of Mount Moco and Mount Soque, near the Cuanza Sul/Huambo provincial border, and is a mosaic of rugged, rocky hills, montane grassland, woodland and forest patches and bare open granites. No rainfall data are available for the site, but rainfall at two localities fairly close-by exceeds 1,500 mm per year. In general, the available habitats for birds and the vegetation are similar to those at Mount Moco, but the forest patches are smaller. Dominant trees in the remnant forest patches include Podocarpus, Polyscias, Apodytes, Pittosporum, Szygium and Halleria, with generally low canopies. Short grasslands with scattered trees and shrubs occur on the hills. Tree and shrub genera include Protea, Cliffortia, Phillipia, Cyathea, Stoebe and Lobelia.
See Box and Tables 2 and 3 for key species. The site qualifies for its assemblage of species characteristic of the Afrotropical Highlands and Zambezian biomes, but the area seems to lack the avifaunal richness of the inselbergs further east (although this may be due to less intensive sampling). Only 130 bird species have been recorded from the site, and many of the records date back to the 1920s and early 1930s, when an expedition from the American Museum of Natural History and the Lynes-Vincent tour collected there. Grus carunculatus is an uncommon resident, and probably breeds. The site is important as one of the few localities where Ploceus nigrimentum occurs—there is no information available on the current abundance and status of this species, but it probably breeds. Two restricted-range species, Dioptrornis brunneus and Nectarinia ludovicensis, are frequent and probably breed. Four species of the Guinea–Congo Forests biome also occur at the site, three of them being either uncommon or fairly localized in Angola: Francolinus finschi, Gymnobucco calvus and Phyllastrephus fulviventris. Species at the site that are part of isolated populations in Angola include Columba arquatrix, Anthus lineiventris, Sheppardia bocagei, Myrmecocichla tholloni, M. nigra, Apalis cinerea, Calamonastes undosus and Muscicapa adusta. Several cisticolas that appear to have isolated populations in this area include Cisticola aberrans, C. lais, C. robustus and C. ayresii. Euplectes gierowi has been collected at Cahata, c.50 km due south of Mombolo, and could occur in wet grassland below the forest patches and in valley bottoms in the Mombolo–Cassongue–Galanga area.
Non-bird biodiversity: None known to BirdLife International.
BirdLife International (2020) Important Bird Areas factsheet: Mombolo (Missão da Namba). Downloaded from http://www.birdlife.org on 23/01/2020.