At the moment there is a lack of instruments to support decision makers in land management projects which aim to evaluate, avoid or cure fragmentation of natural habitats (e.g. ecological networks). These instruments should allow for the development of plans to improve functional connectivity of landscapes as well as for the evaluation of alternative scenario’s. To provide such an instrument for land managers, this projects aims to develop a landscape connectivity model for bats (Chiroptera i.e. common pipistrelle Pipistrellus pipistrellus and serotine Eptesicus serotinus), an important indicator group for habitat quality and biodiversity in Flemish landscapes. Field data are already available, and will be further completed during this project, for two study site: a land re-allotment project in Herenthout-Bouwel and a nature development project in the Laanvallei. Complemented with data from the literature, these data will allow for the study of the quantitative relations between structural characteristics of the landscape and the mobility of bat species. The technical and biological expertise generated in the framework of VLINA-project 97/01 together with the available field data, will allow us to develop a functional landscape model which will be parameterised based on the data of one site. To asses the generality of the results, the model will be validated using the data of the second site.