Since 2008, partridge hunting in Flanders has been subject to a number of conditions. The first condition states compliance with an average density of at least 3 breeding pairs per 100 ha of open space. The Research Institute for Nature and Forest (INBO) is responsible for the calculation of these densities and advises the Agency for Nature and Forests (ANB) on this. This repository contains the source code to generate the layer with open space within hunting grounds in Flanders. The selection is based on relevant categories of the OpenStreetMap information. We aim to make the layer reproducible by making the code publicly available under an open source license. The code itself requires only freeware open source software (R and QGIS). The OpenStreetMap database updates continuously. Rerunning the code on the current database might yield a different layer. Therefore we also republish the snapshot of the OpenStreetMap data we used. When we need to update the open space layer, we will add an updated snapshot as a new version. Having both the code and the data available under version control, allows to recreate both the most recent version as any older version.