The Sudd swamps of southern Sudan are among the most important wetlands for birds in Africa. Three protected areas exist within the Sudd: Shambe National Park and Fanyikang and Zeraf Game Reserves, all within the Bahr-el-Jebel system of the Sudd, the part of the swamps that will be most affected by the Jonglei canal, as and when completed. For current purposes, the core of the Sudd is treated as a single site; this includes the three protected areas and covers much of the Bahr-el-Jebel system between the towns of Malakal to the north and Bor to the south.The Sudd swamps are the seasonally inundated flood-plain of the upper White Nile. They can be divided into four largely distinct sections, of which the Bahr-el-Jebel is the central system and thought to be the most important for birds. The other sections are the Bahr-el-Ghazal system to the west, the Sobat–Baro–Pibor river system to the east and the smaller Machar marshes to the north-east. The Bahr-el-Jebel system consists of two main rivers, the Bahr-el-Jebel, the main course of the White Nile, to the west and the smaller Bahr-ez-Zeraf to the east. The incomplete Jonglei canal lies a little further east. The area is extremely flat with an average slope of only 10 cm per km. The habitats of the area consist of a variety of wetlands, grasslands and woodlands. The wetland can be divided into flowing waters, lakes and permanent swamps. There are three swamp types: Vossia cuspidata swamps (which cover c.250 km²), Cyperus papyrus swamps (c.3,900 km²) and Typha domingensis swamps (13,600 km²). Grassland can be divided into seasonally river-flooded grassland (16,200 km²) and seasonally rain-flooded grassland (20,000 km²). There are areas of single-species woodland mainly of Acacia seyal (5,400 km²) or Balanites aegyptiaca (5,300 km²). Mixed woodland is characterized by Ziziphus mauritiana, Combretum fragrans, Acacia seyal and Balanites aegyptiaca. Average annual rainfall is c.900 mm and falls from late April to November.
See Box and Table 2 for key species. The Sudd swamps hold by far the largest population of Balaeniceps rex. Aerial surveys in 1979–1982 counted a peak of 6,407 individuals. The site is probably also important for Aythya nyroca and, on passage, for Falco naumanni. In addition to those listed below, three species characteristic of the Sahel biome (A03) and five of the Somali–Masai biome (A08) have also been recorded (see Table 2).
Non-bird biodiversity: Mammals of global conservation concern include Loxodonta africana (EN), Panthera leo (VU), Giraffa camelopardalis (LR/cd), Damaliscus lunatus (LR/cd), Gazella thomsoni (LR/cd), Kobus megaceros (LR/nt), K. kob (LR/cd), K. ellipsiprymnus (LR/cd), Redunca redunca (LR/cd), Syncerus caffer (LR/cd), Ourebia ourebi (LR/cd), Hippotragus equinus (LR/cd) and Tragelaphus spekii (LR/nt).
Pressure/threats to key biodiversity
The site includes Shambe National Park (62,000 ha) and its proposed extension, Fanyikang Game Reserve (48,000 ha) and Zeraf Game Reserve (970,000 ha). Since the start of the twentieth century there have been plans to increase the flow of water downstream of the Sudd swamps, principally to provide more water to Egypt, by reducing the amount of water lost by evapotranspiration in the Sudd. This resulted in the construction of the Jonglei canal, a diversion channel on an almost direct line from Bor in the south to Malakal in the north, a distance of 360 km, which began in 1978. It was, however, brought to a halt uncompleted in 1983, by civil unrest in the south of the country. The likely effects of the canal have been much studied, but, if it is ever completed, considerable effort needs to be devoted to monitoring its environmental impact on the Sudd and its important bird populations.The Sudd is inhabited principally by the Nuer, Dinka and Shilluk peoples. In the central and southern parts there are small and widely scattered fishing communities, some on small areas of dry land within the permanent swamp, but most of the population is concentrated on the comparatively small areas of relatively high ground. Up to 1 million livestock (cattle, sheep and goats) are kept within the area. During the dry season, cattle-camps are set up on the banks of the main channels. Populations of larger mammals also congregate here, which leads to some competition for water and grazing. They are hunted and are an important food source. Sorghum, maize, cowpeas, ground-nuts, sesame, pumpkins, okra and tobacco are all cultivated. The heavy, impermeable, low-nutrient soils mean that crop yields are low.