Evaluation de la fonctionnalité des corridors de déplacement du cerf dans le bassin genevois

Abstract

Assessment of the functionality of wildlife corridors used by red deer in the Geneva basin The red deer population located west of the Jura Mountains is expanding its range. For the past fifteen years this expansion has also affected the lowlands of the Geneva basin. When entering the Plateau area, the red deer face a landscape highly fragmented by urbanisation. In addition their natural habitats are broken up and are often reduced to small patches. In this context it is hard to imagine how a red deer population manages to find all the resources required for survival, and how the animals manage to connect the scattered habitats in their area. A study was initiated in 2009 in order to assess this population's use of the space available. Sixteen individuals were fitted with GPS collars in order to monitor their movements. The results show that these individuals manage to connect a set of habitats, forests and agricultural areas, thanks to the presence of transit corridors, the whole system forming a network superposed on the urban network. It was however observed that the functionality of these corridors is often threatened and that their size has been reduced in the last decade. However, even though the landscape matrix is dominated by agricultural environments and is strongly fragmented, the animals are, at present, able to find enough resources by moving between habitat patches using the network which remains. The area thus used to satisfy their essential needs is surprisingly small.