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• Reference and further resources

Site description (2001 baseline)
Widely known as Bushmanland after the inhabitants of this region, the new name is the Tsumkwe District. The original name has been retained because of its widespread acceptance. This very extensive wetland system in north-eastern Namibia has developed on a broad, flat watershed, on the eastern edge of the Kalahari Basin, situated between the Nhoma and Daneib drainage systems. Here, the geology restricts drainage and, as there are no major drainage lines out of the area, these pans, flooded grasslands and Acacia woodlands can remain wet throughout the dry season in years of above-average rainfall. The town of Tsumkwe lies in the centre of the area, which is inhabited by the Ju/’hoan Khoi. Livestock, so common in other parts of Namibia, are largely absent from the area, since a hunter-gathering lifestyle was until recently practised by all the inhabitants. However, cattle-farming has been introduced, and will, in time, replace the traditional nomadic lifestyle.

The Bushmanland Pans system is centred on the Nyae-Nyae wetlands, which run in a broad arc south-east of Tsumkwe. The Nyae-Nyae Pan itself consists of a large deflation basin comprising both grassland and open wetlands. Also included are the Pannetjies Veld wetlands 25 km east of Tsumkwe, comprising mainly flooded woodland, the Klein Dobe wetlands (two pans of 30 and 50 ha) 15 km north of Tsumkwe and the CinQo wetlands 40 km north-east of Tsumkwe. The wetland system as a whole is both extensive and variable.

The wetlands are widely interconnected and many wetland-types intergrade into one another, including: (1) Unvegetated open-water pans with highly alkaline evaporite basins; these pans are the last to dry up and can be up to 1.5 m deep. (2) Doline pans appear to be sinkholes formed in areas underlain by calcrete. When full, these are more than 2 m deep and unvegetated. (3) Open-water pans form where the underlying soils are not very alkaline. Vegetation is dominated by floating and submerged macrophytes such as Persicaria, Scirpus, Nymphaea, Aponogeton, Elytrophorus, Eragrostis and species of algae (Characeae). The pans are of medium size and the water in them can persist for three months. A second type of open-water pan develops where shallow calcareous sands make the pans more alkaline. In these, the vegetation is dominated by sedges (Cyperaceae) and floating mats of Persicaria which form in the deeper parts of the system. (4) Grass pans are small pans where organic clays have impeded the drainage; these are dominated by Echinochloa or Diplachne; the latter are the commonest pans in the system. (5) Wet grasslands develop on calcareous sands where the period of inundation is short. (6) During periods of extreme inundation on clay soils, flooded woodland develops. Occasionally scrubby areas of Grewia and Croton become periodically flooded in years of very high rainfall. The high-lying areas surrounding the pans hold palms such as Hyphaene.

Key biodiversity
See Box and Table 3 for key species. The variety of wetland habitats, ranging from unvegetated open-water systems to wet grasslands, supports a diverse assemblage of flora and fauna. This area holds important numbers of rare and threatened bird species; it regularly holds more than 10,000 waterbirds of 84 species when wet. The most important species include breeding Egretta vinaceigula, and non-breeding Grus carunculatus and Gallinago media; the cranes occur in larger numbers than anywhere else in Namibia. These wetlands are also known to be important for rails (Rallidae), especially migratory Palearctic and intra-African crakes. The pans occasionally support thousands of both Phoenicopterus ruber and P. minor (probably on passage between Etosha and Makgadikgadi Pans in Botswana), as well as thousands of Himantopus himantopus. Tringa glareola and Philomachus pugnax may be particularly numerous, with over 1,000 birds present.

The surrounding grassveld holds Palearctic migrants, including large numbers of Glareola nordmanni and Charadrius asiaticus. Large mixed breeding colonies of Podiceps nigricollis, Chlidonias hybridus, Fulica cristata, Porphyrio porphyrio, Gallinula angulata, Himantopus himantopus and a handful of Porzana pusilla form in flooded grasslands around Nyae-Nyae. It is in the top 20 atlas squares for overall avian species richness in Namibia.

Non-bird biodiversity: Among mammals, the temporary wetland system supports the near-endemic Mastomys shortridgei, and threatened species include Acinonyx jubatus (VU), Lycaon pictus (EN) and Loxodonta africana (EN).

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Recommended citation
BirdLife International (2024) Important Bird Area factsheet: Tsumkwe pan system (Namibia). Downloaded from https://datazone.birdlife.org/site/factsheet/tsumkwe-pan-system-iba-namibia on 22/11/2024.