BUTTERFLY MONITORING SCHEME Report to recorders 2004 The Butterfly Monitoring Scheme Report to Recorders 2004 J NICK GREATOREX-DAVIES & DAVID B ROY CEH Monks Wood Abbots Ripton Huntingdon Cambs PE28 2LS April 2005 CONTENTS Page SUMMARY 1 INTRODUCTION 2 Origins, organisation and aims of the BMS 2 Sites gained 2 Lost sites regained 3 Sites lost 4 Distribution of sites 5 UPDATES ON THE CONTINUED DEVELOPMENT OF THE 6 BMS AND TRANSECT RECORDING Development of transect recording 6 New BMS website 7 A new version of Transect Walker 8 SUMMARY OF THE 2001 SEASON 9 Weather summary for 2003 and 2004 9 Review of trends in 2004 9 Overall changes in abundance: another good year for butterflies 9 Overall changes in phenology 10 Changes in individual species: no highestor lowest indices 11 Spring species improved 11 Whites remain unchanged but Brimstone does well 11 Good year for Holly Blue but most other blues declined 12 A good year for fritillaries 12 Small Tortoiseshell fluctuations 12 A poorer year for migrants 13 Relatively small changes amongst the satyrids 13 Tabular summary of changes 2003 to 2004 14 COMPARISON OF THE 29 YEARS OF THE BMS 16 REFERENCES 17 PUBLICATIONS in 2004/5 17 ACKNOWLEDGEMENTS 18 APPENDIX I Collated indices graphs, 1976-2004 19 Page Figures Figure 1. Fluctuations in the mean index of abundance. 9 Figure 2. Variation in trends of generalist and specialist species measured from over 29 10 years (1976-2004). Figure 3. Trends towards earlier appearance of both spring and summer generations of 10 bi- or multivoltine species. Figure 4. Painted Lady collated indices 1976-2004. 13 Figure 5. Clouded Yellow collated indices 1976-2004. 13 Figure 6. Histogram showing the sum of the ranks of 33 species plus univoltine 16 Common Blue for the period 1976-2004. Figure 7. Log collated indices, 1976-2004. 20 Tables Table 1. Summary of changes 2003/4. 15 Maps Map 1. The distribution of BMS (including ECN sites) sites in 2004. 5 SUMMARY 1. This report reviews the national Butterfly Monitoring Scheme (BMS) for the 2004 season and marks the twenty-ninth year of monitoring since the scheme started in 1976. 2. The year 2004 was an above average year for butterflies in general, ranking 12th highest of the series (1976-2004) only slightly poorer than 2003 which ranked 10th highest in the series and was the best year since 1997. Of the 50 species and generations for which overall indices of abundance were calculated, 23 increased from 2003 to 2004, 26 showed a decrease and one no change. 3. No species produced their highest index though the Silver-washed Fritillary and the first generation of the Adonis blue produced their second highest index of the series. No species produced their lowest index. 4. There was an improvement in the indices of most species flying in the spring, probably largely due to the good summer of 2003. The Brimstone and Holly Blue did particularly well. 5. Most violet feeding fritillaries improved especially Silver-washed Fritillary and Dark Green Fritillary which both produced high indices. Satyrids showed small changes with many species retaining a high index and the Small Heath, which increased dramatically in 2003, showed a further increase. Conversely the Wall Brown remains very low declining further in 2004. After a big increase in 2003 the Small Tortoiseshell, which has shown large fluctuations in recent years, dropped by nearly 40% to produce an average index. 6. Migrant species did rather less well than in the good migrant year of 2003, particularly the Red Admiral, whose index dropped by 75% from 2003. It was the poorest year for this species since 1991. 7. The day-to-day operation of the scheme is run by Mr Nick Greatorex-Davies at the Centre for Ecology and Hydrology (CEH, formerly ITE), Monks Wood. Mr David Roy (CEH Monks Wood) has overall responsibility for management of the BMS. He is also responsible for the technical aspects of the scheme, and co-ordination of research using the BMS. The BMS is jointly funded by the Joint Nature Conservation Committee (JNCC) and by CEH. 8. Data were received from 134 transects (including 14 Environmental Change Network (ECN) transects) for the 2004 season. For 8 of these transects data too few for any annual indices to be calculated. Data from 2 transects were collected but were not submitted in time to be included in the analysis for this report. Five transects joined the scheme in 2004 and three rejoined. Two sites were lost from the scheme. 9. Data were received electronically from Transect Walker software from 47 transects; this is a slight drop from 54 in 2003. The new version of the Transect Walker software is undergoing final tests before being released later this year. 10. A three-year contract with Defra which commenced in January will enable the joining together of the two schemes run by Butterfly Conservation (BC) and CEH. It will also enable the development of an extension to the scheme to monitor butterflies in the wider countryside. 11. Recent and forthcoming publications using data from the BMS are listed. 12. Appendix I contains graphs showing annual fluctuations in the all-sites collated indices from 1976-2004 1 INTRODUCTION The purpose of this report is to review the Butterfly Monitoring Scheme (BMS), to summarise the results of the scheme for the year 2004 and to provide updates on recent developments in transect recording. The main aim is to give feedback to the many transect recorders, site managers and site owners involved with the scheme. Origins, organisation and aims of the BMS The BMS was launched in 1976 by Dr Ernie Pollard based at the Institute of Terrestrial Ecology (ITE) at Monks Wood. The scheme was initially financed jointly by the Nature Conservancy Council (NCC) and ITE. Since 1991 it has been jointly financed by the Joint Nature Conservation Committee (JNCC) (acting on behalf of the statutory conservation agencies (successors to NCC): English Nature, Countryside Council for Wales, Scottish Natural Heritage and the Environment and Heritage Service Northern Ireland), and ITE (now the Centre for Ecology and Hydrology (CEH)). The day-to-day operation of the BMS continues to be run by Mr Nick Greatorex-Davies and Mr David Roy has overall responsibility for the management of the scheme. Dr Ernie Pollard retired from active involvement in the scheme in 1998 (apart from walking a transect as part of the scheme) but still provides advice when required. The BMS has benefited greatly from close collaboration with Butterfly Conservation (BC) for several years. We are now entering a formal partnership, funded by a multi-agency consortium led by Defra, to integrate the BMS and BC transect schemes with the aim of launching a combined scheme in spring 2006. See the ‘Updates’ section of the report for the full details. The primary aims of the scheme are to provide information at regional and national levels on changes in the abundance of butterfly species, to detect trends which may indicate changes in their status and to provide a reliable long-term reference against which population changes in species studied elsewhere on individual sites, or in other countries, can be monitored. It also aims to monitor changes at individual sites and, by comparison with results elsewhere, to assess the impact of local factors such as habitat change caused by management. The scheme also provides information on aspects of the population ecology and phenology of individual species, both in relation to the effect of environmental changes (including climate change) and as a contribution to butterfly ecology. Sites gained Five new transects were brought into the BMS in 2004. Three of these were in Scotland and two in England. These are Aberarder and Scamodale in Highland, and Cragbank near Hawick in the Borders. Two transects are in England, these are Torrington Commons in Devon, and Wootton Coppice in Hampshire. Aberarder is a high altitude single species transect that was set up in 1995 on the high slopes of Creag Meagaidh to monitor the Mountain Ringlet. Small Pearl-bordered Fritillary, Dark Green Fritillary, and Scotch Argus are also recorded on the transect. A second transect (called Creag Meagaidh) on the lower slopes of the mountain is already part of the BMS. 2 Scamodale is on the west shore of Loch Sheil, west of Fort William. It is a single species transect that was set up in 2003 to cover the habitat and flight period of the Chequered Skipper. The recording period also covers the flight period of several other scarce species which occur at the site, these are Pearl and Small Pearl-bordered Fritillaries and Green Hairstreak. It is primarily a wet heathland site where tussocks of Purple Moor Grass abound bordered by actively managed plantation coniferous woodland. Data for both 2003 and 2004 have been added to the BMS database. Cragbank is a National Nature Reserve in the Scottish Borders a few miles SE of Hawick near the Northumberland border. The transect was set up in 2004 mainly to monitor the population of Northern Brown Argus that occurs on the site. It was hoped that coverage could be maintained throughout the season but this may not be feasible. The site is mostly a small (8.8.ha) ancient ash-elm-hazel woodland but in addition has some moderately herb-rich grassland on the upper edge of the woodland where the Northern Brown Argus occurs. Torrington Commons is at Great Torrington, a few miles south of Bideford in Devon. The transect began in 2003. The site is particularly good for the violet feeding fritillaries.