Niayes (from Dakar to St Louis)

Country/territory: Senegal

IBA criteria met: B1a, B3a (2019)
For more information about IBA criteria, please click here

Area: 4,000 ha

Nature - Communautés - Développement

Site description (baseline)
This site consists of a string of permanent freshwater lakes and additional temporarily wet depressions (niayes) lying along a line running north-east from the outskirts of Dakar to around 60 km south-west of St Louis. The lakes lie behind the ridge of coastal sandy dunes, in shallow depressions at 1–4 m above sea-level, over a distance of c.150 km. They are replenished both by rainfall and from the underlying water-table, which lies close to the surface. The wetlands cover 40 km² at low water; at high water, all the lakes can increase their surface area five-fold. The largest lakes lie at the southern end and include Nhiarhol Pool and the lakes Mbao, Mbeubeussé, Retba, Tanma, Youyi (or Malika) and Ourouaye. Lake Retba is the largest, with an open water surface of 5 km by 1.7 km wide at low water. Niaye Hann Mariste consists of a depression covering a surface area of about 30 ha (1.3 km by 200 m), but this dried out completely in 1997 due to evaporation, compounded by abstraction of water for agriculture and building construction. The surrounding vegetation is subjected to seasonal inundation and the area is characterized by the oil-palm Elaeis guineensis. There are also elements of vegetation more typical of the Sudan–Guinea Savanna biome and Guinea–Congo Forests biome (e.g. Prosopis africana and Ficus capensis). These are able to flourish here due to the high moisture content of the soils, which results from the water-table lying close to the surface and the moisture-bearing Alizé winds blowing in from the Atlantic. The whole site is very important in terms of human use, for cattle-grazing, fishing, vegetable, fruit and rice-growing and market gardening (estimated at 90% of national production). Many of the individual lakes also have religious and cultural significance.

Key biodiversity
See Box for key species. The lakes were included for the first time in the African Waterbird Census in 1997, when nearly 4,000 birds were counted. The niayes have also been the subject of a number of recent more detailed studies (notably by Pierre Reynaud and colleagues at the Institut de recherche pour le développement, IRD), which reveal them to be some of the most ornithologically diverse and most threatened sites along the whole coast of Senegal. In Niaye Hann Mariste alone, Reynaud has recorded 147 bird species, including 51 breeding. The niayes as a whole are particularly important for a wide variety of breeding and wintering waterbirds and also raptors. Up to 500 Phoenicopterus minor were recorded at Lac Tanma in 1990, Falco naumanni is reported in small numbers from the site and there are huge roosts of Milvus migrans.

Phoenicopterus ruber is a regular winter visitor and the site appears to play a key staging role for birds coming from regions further north (Baillon pers. comm.). A maximum count of 3,000 was recorded in 1975 on Lac Tanma; if these numbers are a regular occurrence, they will additionally qualify the site as an IBA. Similarly, a maximum number of 3,200 Recurvirostra avosetta recorded on Lac Youyi in 1975 would qualify this lake as an IBA in its own right, if regularly occurring; the species is also regularly recorded elsewhere within the site. In addition to those in the Box, other species wintering in significant numbers include Egretta garzetta and Anas clypeata. There are records of large numbers of wintering and passage Sterna sandvicensis (7,500 between site SN006, Parc National de la Langue de Barbarie, and the town of Kayar; plus 13,000 from Kayar to Cap Vert) and S. albifrons (1,500 between Kayar and Cap Vert). In both these cases, the numbers will include birds using the niayes, but these counts also cover a wider area including the whole coastal strip. Breeding birds recorded on the site include Phalacrocorax africanus. Six species of the Sudan–Guinea Savanna (A04) biome have been recorded from this site (see Table 2), reflecting the humid coastal climate, which encourages vegetation-types typical of more southerly zones.

Non-bird biodiversity: None known to BirdLife International.

Recommended citation
BirdLife International (2023) Important Bird Area factsheet: Niayes (from Dakar to St Louis). Downloaded from on 01/06/2023.