Mapping critical and sensitive areas in the buffer zone of the W’s - Transfrontier Biosphere Reserve Within the Ecopas framework, which is an Eu environmental cooperation program, a critical and sensitive areas mapping has been developed in order to support the decision within the Rbt/W governance (Burkina Faso, Benin, Niger). The Rbt/W system equilibrium relays on both geographical interaction and distribution of critical areas located on the cross border of the three countries involved. If one of those collapses, a chain of critical events might take place with heavy consequences for other border areas, as well as within the W Park itself. Concerning monitoring and intervention strategy, Ecopas and its partners focus their actions in those crowded areas (environmental conflicts, land pressure, cattle migration, institutional crisis).