In connectivity conservation and ecological network planning, the selection of focal fragmentation-sensitive species represents an a priori step. Despite their strategic role, selection of focal species has often been carried out following non-objective approaches. If this is done, actions of planning and conservation, especially in relation to biodiversity conservation, could be ineffective. We propose an expert-based approach to select focal species on the basis of sensitivity to three components of habitat fragmentation (habitat area reduction, increase of habitat isolation, increase of edge effect and landscape matrix disturbance) and of intrinsic ecological traits of the species (trophic level, dispersal ability, body size, niche breadth, rarity). A case study on terrestrial mammals of an area in Central Italy (province of Rome) shows that the species selected through this approach largely coincide with the species recognized in the literature as being fragmentation-sensitive. In this paper we present a conceptual framework to select focal species and to define a schematic methodology for ecological network planning and monitoring.