Monitoring van libellen in Nederland

The current method to monitor dragonflies in The Netherlands is outlined. Counts of dragonflies are carried out along the shore of reproduction sites. A count is valid only when some conditions are satisfied like fine weather, time of the day and time of the year. The use of densities along the water is discussed and it is set forth that densities reflect actual population size and indirectly reflect the quality of the reproduction site. It is expected that the sensitivity of the discussed monitoring method is satisfactorily for most species. For some species, namely those with extremely low densities, those which spend most of their time away from water and migrants the sensitivity is likely too low to assess trends.