Mapping the distribution of dragonfly records in atlases illustrates how the known range of species has changed, but it is a blunt instrument for monitoring dragonfly populations at a national or local scale. This is best referred to as surveillance monitoring and requires a regular flow of records from many sites all across Britain. In DragonflyWatch, surveillance is being carried out using information from Site Lists gathered during single visits to dragonfly breeding waters. Periodic status reports will be published on this website. As well as providing national population indices, the results will also allow Britain to contribute to Europe-wide dragonfly monitoring.
In order to monitor change at individual sites, however, greater detail is needed and so other methods are more appropriate. Site monitoring needs commitment and concerted input over a number of years in order to obtain meaningful results. The method used needs to be robust to changes in habitat and ideally changes in people, and must be applied consistently. Guidance on how to monitor important dragonfly sites is given here.
These recording forms may be useful:
Monitoring methods are not suitable to determine the value of a site for dragonflies. This is best done by obtaining evidence of presence, abundance and breeding during a series of visits during fine weather. Visits should be spread over the flight season and ideally over several years, to account for annual population fluctuations. The information gathered can be assessed against criteria for Priority Sites (also known as Key Sites).