22.214.171.124 Butterflies are well-documented, recognisable and popular with the public.
126.96.36.199 Data is available for 42 of the 50 regularly occurring butterfly species in the South West since 1990, from annual abundance data collected at 300 monitored sites.
188.8.131.52 The species can be divided into two categories: habitat specialists that are largely restricted to blocks of semi-natural habitat and wider countryside species that can utilise a broader range of habitats, including linear features across intensively managed countryside (Asher et al., 2001). Butterfly indicators can play an important role in assessing habitat diversity, habitat fragmentation and the impacts of climate change.
184.108.40.206 Butterfly numbers have fluctuated greatly from year-to-year largely according to weather conditions and the assessment is based on an analysis of an underlying 'smoothed' trend. This analysis shows that both habitat specialist and wider countryside species have declined substantially since 1990.
220.127.116.11 For habitat specialist species, the smoothed index in 2008 was significantly lower than over the period 1990-2007, with the 2008 index 65% lower than in 1990. Similarly for wider countryside species, the smoothed index was significantly lower in 2008 than from 1990-2007, with abundance halving since 1990.
18.104.22.168 For 15 of the 42 species assessed, the trend was classed as a rapid decline, including for seven habitat specialists. One species increased rapidly (the calcareous grassland specialist, the Adonis Blue), whilst 26 species
had a stable trend. The habitat specialists in significant decline were High Brown Fritillary, Grayling, Duke of Burgundy, Wood White, Chalkhill Blue, Silver-studded Blue and Grizzled Skipper.
22.214.171.124 This indicator is a multi-species index compiled by the Centre for Ecology and Hydrology and Butterfly Conservation, primarily from the UK Butterfly Monitoring Scheme. Annual indices for each species at each site
were calculated from weekly counts over the season (Rothery and Roy, 2001).
126.96.36.199 The indicator has potential to be updated annually.