Evolution of Sudano-Sahelian African Elephant population numbers : stakes for conservation

The first objective of this thesis was to analyze the evolution of Sudano-Sahelian African elephant populations in a context of environmental challenges and increasing human demography. The second objective was to propose solutions for elephant conservation in the Sudano-Sahelian context. To fulfill these objectives, aerial surveys have been carried out in every protected area harboring a known population of elephants. This work was first implemented at a local level on several study cases and finally at a global level. Results of aerial surveys estimate the current elephant number at minimum 7,745 elephants, about 2% of the African elephant total population. This confirmed that the elephant populations have been progressively fragmented and confined to few protected areas representing 5% of the Soudano-Sahelian strip. The long term (four decades) elephant population trends has been studied by comparing our results with the database of the study area. The half of the monitored population collapse during the last 40 years. The viability of small elephant population of 200 elephants and below is critical and several of them collapsed. Contrasted local situation have been observed : if a number depletion is often observed, in some protected areas elephant populations are stable or increasing. Although, trends of other large mammals’ population is not linked to that of the elephants. This result allow to conclude that the elephant is not a good indicator of the abundance of other large mammals’ population. Causes of elephant populations’ depletion are both due to climate change (global drought) and socio-economic (human demography and land use pressure) issues. An appropriate and permanent field management, a better valorisation of elephants and the creation of negotiated corridors with local people could garantee the future of Sudano-Sahelian African elephants