In the UK Butterfly Monitoring Scheme (UKBMS), annual data on the population status of butterflies is derived from a wide-scale program of site-based monitoring and sampling in randomly selected 1km squares. The sampling framework comprises: (1) Weekly butterfly transects (Pollard walks); (2) Reduced effort surveys of habitat specialist species (including timed counts of adults, single species transects, and egg and larval counts); and (3) the Wider Countryside Butterfly Survey (WCBS). The resulting UKBMS dataset is one of the most important resources for understanding changes in insect populations and answering policy questions relating to status and trends in biodiversity…

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