Understanding and predicting how bird populations and land cover respond to natural and anthropogenic changes is a major challenge for environmental planning. Multi-agent modelling enables horizontal relationships (spatial configurations) and vertical relationships (socio-economic organisation) to be integrated. GEMACE is a multi-agent model for simulating farming-hunting-duck interactions in the Camargue (Southern France). For an archetypal region, we simulated land-use conversion and ecological change in space and time resulting from the interaction between environment and human drivers. A wintering duck population is simulated and distributed heterogeneously in its habitats. The duck population is affected by various environmental factors such as land-use changes, wetland management, hunting harvest, and disturbance. Land-use decisions are made at farmland level by farmers and hunting managers. Important biophysical drivers are water and salt through land relief, land-use history, infrastructure, spatial neighbourhood, and current land use. Important human drivers are the economic conditions of the world agricultural market and land-use strategy. Through three scenario runs, we discuss the implications that can be drawn from this modelling application with regard to the viability of a spatial conservation management alternative and multi-field research on sustainable development.