Methods
Data from systematic studies control and report sampling effort allowing
to estimate standardized roadkill rates (number of individuals killed
per area and time span) for different species and areas. However, these
studies, and thus their data, are often limited to particular road
sections and periods of time. On the other hand, citizen science data
can cover wider spatial and temporal windows, but sampling is often not
regulated or quantified making the definition of standardized estimates
complicated. To avoid methodological issues, data obtained from these
two approaches are presented separately.