The site lies in the delta of the Casamance river in the south-western corner of the country. It lies to the south of the main river channel, close to the border with Guinea-Bissau, and c.50 km south-west of Ziguinchor. It is low-lying, with the highest areas in the eastern end of the park (maximum altitude 11 m above sea-level). The habitat consists of mangroves fringing tidal channels, seasonally bare saline mudflats, some wooded savanna and terrestrial forest, including the only remaining small area of Guinea–Congo forest in the country. The mangrove areas show a zonation from the water’s edge, with first Rhizophora racemosa, then R. mangle with Paspalum vaginatum, then Avicennia africana with R. mangle, and Scirpus littoralis or other understorey species. The mudflats are colonized by Eleocharis mutata and E. geniculata. The Guinea–Congo forest occurs as islands within the Santiaba–Mandjak forest and includes species such as Parinari excelsa, Pithecellobium altissimum, Chlorophora regia, Detarium senegalense, and abundant Treculia africana forming the lower canopy.
See Box and Table 2 for key species. The site is the only IBA in Senegal in which two of the country’s globally threatened species, Ceratogymna elata and Illadopsis rufescens, are recorded. C. elata is said to occur as a small population seen regularly in the park and I. rufescens was caught in mist-nets twice in the 1970s and 1980s (one individual on each occasion). Circus macrourus has also been recorded at least once in the park. The wooded savanna and Guinea–Congo forest areas hold a number of species restricted to the Sudan–Guinea Savanna (A04) biome, including Nectarinia coccinigaster, recorded from no other IBA in Senegal. Nearly all of the species restricted to the Guinea–Congo Forests (A05) biome that are known to occur in the country are also recorded from the site. The site is said to be important for Palearctic migrant waders, but no numerical data are available.
Non-bird biodiversity: Over 50 mammal species have been recorded from this small area, including Piliocolobus badius temminckii (LR/nt) and Trichechus senegalensis (VU). The park hosts a variety of duikers (Cephalophus spp.) and Anomalurus beecrofti is found nowhere else in Senegal. Reptiles include Osteolaemus tetraspis (VU).
Pressure/threats to key biodiversity
The park itself is well managed, but is small and close to several population centres (Oussouye, Ziguinchor). The ungulate Kobus kob has been successfully reintroduced to the park. There are pressures on areas outside the park boundary, including both an estuarine and an offshore fishery and mangrove exploitation. The whole of the lower Casamance river and delta are threatened by increases in salinity resulting from reduced rainfall over the last 30 years and the intrusion of salt water further upstream. This has led to localized losses of fish species and pollution of groundwater. IUCN organized a seminar on behalf of the government and produced recommendations on ‘Conservation and Sustainable Use of Natural Resources in the Casamance River Basin’ in 1990. However, the park was closed in 1992 as a result of the conflict and unrest that has occurred in the Casamance region in recent years, and subsequently no monitoring of birds or the conservation status of the area has been possible.
BirdLife International (2020) Important Bird Areas factsheet: Parc National de Basse Casamance. Downloaded from
http://www.birdlife.org on 21/01/2020.