Weekly monitoring along transects is conducted. Butterflies are one of the easier insect groups to identify and monitor and are known to respond rapidly to changes in vegetation abundance and quality. The Protocol adopted by ECN is that already in use for the national Butterfly Monitoring Scheme, operated jointly by the Centre for Ecology & Hydrology and the Joint Nature Conservation Committee and organised by the Biological Records Centre. This existing scheme provides a strong background of information for comparison with ECN data.