The Cunene river, like the Orange river, forms an east–west linear oasis of permanent freshwater across the northern Namib desert before reaching the Atlantic Ocean. It is a warm-water river, with highly variable annual flow volumes differing as much as 14-fold between and high and low years. It also varies within years by as much as 11-fold between high flow in April and low flow in October. The lower Cunene is the 340 km stretch of river that forms the border between Namibia and Angola. The mouth is considered to be the lower part of the river within 4 km of the coast. Flow to the sea is never closed off, even though it may naturally slow to a trickle in September–October. Epupa Falls, about 190 km upstream, is the last major waterfall along this very steep river that flows for 1,050 km from source (in the Angolan highlands) to mouth. It also marks the proposed site for a hydroelectric dam, which would produce a body of water c.75 km in length. At present hydro-power in Namibia is only generated from the diversion weir located at Ruacana, the end point of this IBA. Either side of the river, rocky cliffs, wind-stripped plains and dune-fields mark its progress through the hyper-arid desert. The river is typically confined to rocky gorges for most of its 340 km journey along the border of Angola.
See Box and Tables 2 and 3 for key species. The river and surrounding areas support over 300 bird species. River surveys have revealed c.92 wetland birds/10 km of river (comprising mainly herons), with more birds and species occurring in the western reaches. Where dense ribbons of palms fringe the river, birds occur at much higher densities (132 birds/10 km) than areas without palms (34 birds/10 km). The riparian fringe is home to two highly localized species found nowhere else in southern Africa. These are Cichladusa ruficauda and the near-threatened Estrilda thomensis. Both are associated with Hyphaene palms and adjacent riverine thickets. Several species have isolated populations here, hundreds of kilometres from their stronghold in the Okavango and adjacent wetlands. These include Turdoides hartlaubii, Lagonosticta rhodopareia, Ploceus xanthops, Malaconotus blanchoti and Ceyx pictus. A distinctive race of Francolinus afer also appears here, with the closest other southern African records being in eastern Zimbabwe. These species co-occur with near-endemics such as Turdoides gymnogenys, Namibornis herero, Poicephalus rueppellii and Lanioturdus torquatus.
Non-bird biodiversity: Five species of fish are endemic to the river, of which a newly discovered (1997) species may become extinct if the proposed dam development goes ahead, since it breeds in shallow water on flooded banks. A snake new to science, Coluber zebrinus, was recently discovered here. Elephants Loxodonta africana (EN) use the river as an oasis.
BirdLife International (2022) Important Bird Areas factsheet: Epupa - Ruacana. Downloaded from http://www.birdlife.org on 20/05/2022.