Mimosa asperata and Salix chevalieri grow above a Cyperus maculatus understory. Northern Delta Characterized by emergent sand ridges which sustain the palm trees Hyphaene thebaica and Borassus aethiopum, the gum arabic tree Acacia nilotica, Guarea senegalensis, Mimosa asperata and Ziziphus mauritiana. Fauna The delta is home to birds in large numbers including hundreds of thousands of wintering garganeys, pintails and ruffs and breeding colonies of cormorant, heron, spoonbill, ibis and other waterbirds including the endangered West African subspecies of black crowned crane (Balearica pavonina pavonina). Most large mammals have been removed from the area by the human population. Mammals remaining include the African manatee, known as the sea cow which lives in the rivers and feeds on underwater plants. And the rivers are rich in fish including two endemics; the Mochokidae catfish Synodontis gobroni and a cichlid, Gobiocichla wonderi. Threats and preservation The construction of a large irrigation project upstream of the Inner Niger Delta threatens its ecology and the livelihoods of its inhabitants. The 100,000 ha project is an extension to the area irrigated by the Office du Niger through the Malibya canal. The extension, which was under construction in 2010, is financed by the Libya Africa Investment Portfolio which will also have the right to exploit the irrigated land. According to James Leten, a researcher, the project will reduce the area under deep inundation in the Inner Niger Delta by 43 percent. The area under deep inundation is crucial for pastoralists, because only there Borgou (Echinochloa stagnina) grows, a plant which is particularly nutritious for cattle. Nomadic pastoralists come from as far away as Burkina Faso and Mauritania to allow their cattle to graze on the Borgou of the Inner Niger Delta. According to a report in Jeune Afrique, the researcher tried to alert the authorities about the need to find alternative livelihoods for the pastoralists, apparently without success. Three Ramsar sites, a total of 1,620 km2 have been declared in the delta; Lac Horo, Lac Debo, and the Séri floodplain. But the delta is largely unprotected and at the same time fishing and farming in the delta is vital to the livelihoods of the people of Mali. Low water levels in the rivers, lack of rain, increasing human population and a break-up of the traditional tribal arrangements for sharing the resources of the delta are all factors that may contribute to severely damaging the ecosystem. In particular