The site consists of a length of about 21 km of the Senegal river and its immediate riparian habitat. It lies upstream of Djoudj wetlands (site SN001) and north of both Ndiaël basin (SN002) and Lac de Guiers (SN003). The habitat consists of highly modified and cultivated areas of land, with extensive rice-fields and market gardens and associated irrigation and drainage canals and ditches, adjacent to areas of fairly dense human habitation. The site is very closely linked to Lac de Guiers, which receives water from the river through sluices and a canal located at Richard-Toll. Between this site and Lac de Guiers lie extensive sugar-cane plantations. The site lies in the Sahel zone and the original habitat would have been thorn-bush savanna, dominated by Acacia spp. and Balanites aegyptiaca, shrubs of Bosciasenegalensis and Salvadora persica, and larger trees adjacent to the river itself, including Combretum aculeatum, Grewia bicolor, Bombax costatum and Borassus aethiopicum. There were once extensive forests of Acacia nilotica along the banks of the Senegal river that were regularly inundated by floods and formed important refuges for Palearctic migrants. These forests have largely disappeared as a result of drought and exploitation for fuelwood.
See Box and Table 2 for key species. This site is unique in Senegal due to the presence (for more than 35 years) of ornithologists Gérard and Marie-Yvonne Morel at the ‘Station d’Ecologie’ in Richard-Toll, funded by the French overseas research organization IRD (formerly ‘ORSTOM’). As a result of their work and that of other visiting research staff using the station, the intensity of bird observations for Richard-Toll and the immediate area far exceeds that for almost any other area of the country. The site is important for many waterbirds and some raptors. There are past records of the globally threatened Marmaronetta angustirostris (but none recorded since the 1970s), and more recent records in the general area of the site for Circus macrourus and Falco naumanni, both of which are recorded on passage in the lower Senegal valley. There is also a record of ‘thousands’ of F. naumanni from Richard-Toll in 1958. Observer effort is reflected particularly in the biome-restricted species lists. Seven species of the Sudan–Guinea Savanna biome (A04) have been recorded from the site (Table 2). In addition to the count of 26,000 Philomachus pugnax in 1994, there are several other recent records of significant totals of this species as well as suspected roosts or pre-roosts in rice-fields in the general area of the site (e.g. at Boundoum), suggesting that the species is regularly occurring. Other records of waterbirds at Richard-Toll include breeding Casmerodius albus, Threskiornis aethiopicus and Platalea alba, and wintering Nycticorax nycticorax (though several of the breeding records in particular are from earlier decades).
Non-bird biodiversity: The mammal Trichechussenegalensis (VU) probably still occurs in the river, although sightings are infrequent (a stranded individual was rescued from the river at Matam in 1997, several hundred kilometres upstream of Richard-Toll).
Pressure/threats to key biodiversity
The site is completely unprotected and there are dense centres of human population on the riverbanks, especially at Richard-Toll and Rosso (a river and border crossing to Mauritania). Overgrazing, deforestation, pollution and disturbance constitute existing or potential problems throughout the entire site. Despite this degradation, the site remains important for birds (especially biome-restricted species) and is considered to merit IBA status. Future work may lead to the identification of a smaller site of greatest importance, which would be amenable to some form of conservation action, and possibly the designation of protected-area status. The ‘Organisation pour la Mise en Valeur du fleuve Sénégal’ (OMVS) was established to ensure sound and integrated management of the whole river basin (including artificial flood releases controlled by two major dams—one in Mali and the other above St Louis at Maka Diama). This has never functioned as intended and the main objectives were, in any case, increases in irrigated agriculture (especially rice) rather than any environmental considerations. A workshop in 1995, under the auspices of the OMVS, discussed the problems of managing water-bodies in the Senegal river basin and resulted in recommendations for minimizing environmental and health impacts. An initiative to establish a National Wetlands Network (Réseau Zones Humides du Sénégal) is also intended to lead to wider application of the Ramsar principles of wise use, to cover wetland areas which have no formal protected-area status. It is not clear how effective these measures will be in relation to the site.
BirdLife International (2019) Important Bird Areas factsheet: River Sénégal (Ntiagar to Richard-Toll). Downloaded from
http://www.birdlife.org on 20/11/2019.