The Ruaha–Kilombero–Rufiji is the longest and largest river system in Tanzania, draining much of the southern highlands, southern areas of the central plateau and the coastal lowlands. The delta of the Rufiji river is the largest tidal mangrove wetland on the eastern coast of Africa. Mangroves cover an area of 54,500 ha within the delta, and are protected as the Mangrove-Rufiji Forest Reserves. Seven genera of mangrove occur, with Rhizophora, Avicennia and Heritiera dominant. There are several small settlements within the delta.
See Box for key species. The avifauna of the delta is poorly known. The mangroves are probably a roosting site and feeding ground for tens of thousands of migrant waterbirds, but fieldwork is required to confirm this. A recent survey has added to earlier counts, which covered only around 10% of the delta area. Both counts revealed good numbers of waders including, in addition to those listed below, 2,366 Calidris minuta and 199 Charadrius asiaticus. Lamprotornis corruscus breeds almost exclusively in mangrove forest; in all six species of the East African Coast biome have been recorded (see Table 3).
Non-bird biodiversity: None are known but the mammal Dugong dugon (VU) may still survive in some of the cleaner waters.
Pressure/threats to key biodiversity
There were proposals for a 10,000 ha prawn farm that would have effectively destroyed much of the natural habitat of the delta. It is anticipated that smaller proposals may now be brought forward which are still likely to damage the integrity of the site. Lamprotornis corruscus is dependent on mature trees for nest-holes. The frequent cutting of mangroves does not allow them to fully develop and the growing habit of cutting ‘dead’ trees for firewood further reduces habitat viability for this starling and other hole-nesting species such as Pogoniulus pusillus, Lybius melanopterus and Halcyon senegaloides. These mangroves are Forest Reserves, and are therefore protected by law; this needs much improved enforcement.