THE HERTFORDSHIRE PURPLE EMPEROR APATURA IRIS LIZ GOODYEAR & ANDREW MIDDLETON JUNE 2003 Report supported by The Hertfordshire Natural History Society Front cover illustration by Liz Goodyear Index 1. Abstract 2. Introduction 2.1. Contributors 3. Historical Hertfordshire records 3.1. Purple Emperor A.iris species account by Brian Sawford (Sawford 1987) 3.2. Original and/or additional historical notes and reports concerning A.iris in Hertfordshire and adjacent areas 3.3. Further notes on later sightings of A.iris in Hertfordshire and adjoining areas, many previously unpublished, and some concerning additional records 3.4. Extracts from the Hertfordshire & Middlesex Branch of Butterfly Conservation’s Annual Butterfly & Moth Reports for 1995 ~ 2000 (Murray, Souter, Wood) 4. Surveying and results for 1999-2002 5. Annual charts for 1999-2002 5.1. 1999 5.2. 2000 5.3. 2001 5.4. 2002 5.5. Overview of the flight season 6. Individual accounts of locations found to have A.iris, 1999-2002 6.1. Site A 6.2. Site B Tring Park 6.3. Site C 6.4. Site D 6.5. Site E Broxbourne Wood Nature Reserve 6.6. Site F 6.7. Site G Broad Riding Wood / Broxbourne Common 6.8. Site H 7. Historic and potential areas for A.iris 7.1. Wormley, Bencroft, Danemead, Hoddesdonpark and Box Woods (TL30) 7.2. North Hertfordshire (Hitch Wood, Knebworth, Astonbury Wood and St. John’s Woods) 7.3. The Welwyn area (TL11 and TL21) 7.4. The Northaw and Cuffley area 7.5. North-east Hertfordshire 7.6. South-west Hertfordshire 7.7. West Hertfordshire 8. Notes on the habits of A.iris as observed in Hertfordshire 8.1. Male territorial activity 8.2. All other activity including grounding and female activity 9. Notes on distribution, weather and climate relating to A.iris in Hertfordshire, U.K. and Eurasia 9.1. A look back at the recorded distribution of A.iris in Hertfordshire 9.2. Notes on weather in Hertfordshire during the flight period and larval stages 9.3. Reference material and notes for A.iris distribution, climate and habitat associations 10. Maintaining and increasing available habitats 10.1. Sallows: flowers and seeds, species and leaves, lifespan, loss, biodiversity and surveying 10.2. Discussion of sallow numbers, larval predation and numbers of adult A.iris 10.3. Past management which has resulted in habitat for A.iris 10.4. Recent efforts for positive habitat management 10.5. Suggestions for managing for A.iris within different woodland systems 10.6. Action plans; liasing with woodland owners, managers and other relevant organisations 11. References Appendix I Extract from An Illustrated Natural History of British Butterflies by E. Newman (1874) Appendix II Some historical notes regarding A.iris in Essex, gathered during our studies Appendix III Abbreviations used within text Appendix IV Scientific names of taxa referred to in text 9.1a Colour images 1 ~ Abstract During the study period from 1999 to 2002, Purple Emperor Apatura iris was found to be resident at low density across three 10km squares in Hertfordshire. Several colonies were found or confirmed by patient observation and increased awareness, combined with a better understanding of the habits of A.iris , in particular male territorial activity. Gathered historical records indicate that A.iris has been present in Hertfordshire for many decades, probably since the first records in the 1800s. Colonies have been found to be associated with an abundance of sallows in coppice regrowth and plantation, generally up to 25 or 30 years old, in woodland complexes having a mature deciduous element. A.iris appears to have survived in Hertfordshire by being able to colonise new areas and woods, to some degree, as they have become suitable. After the loss of many sallows through thinning at one location, sightings of A.iris here were severely reduced the following summer, whilst other populations nearby and elsewhere in Hertfordshire appeared to remain stable. Notes are given on the observed lifestyle of A.iris and its habitats. Historical notes are presented, climate and ecology are considered, and progress with the A.iris Species Action Plan is detailed. Possibilities for management in favour of both A.iris and general woodland biodiversity are discussed. Ideal habitat for A.iris was not found to be widespread in Hertfordshire at present, however, given timely and appropriate decisions regarding woodland management and sallows, the species could be relatively simple to manage for on a less than annual basis. Liz Goodyear, Andrew Middleton, 7, Chestnut Avenue, 46, Bursland Road, Ware, Enfield, Hertfordshire, Middlesex, SG12 7JE. EN3 7EX. Telephone: 01920 487066 Telephone: 020 8245 0847 5th edition ~ September 2003 1 2 ~ Introduction ~ Liz Goodyear (LG) and Andrew Middleton (AM), June 2003 We would like to thank the Hertfordshire Natural History Society for sponsoring the report. It is intended to bring together all the information which has been gathered so far regarding A.iris past and present in Hertfordshire, and it details any progress we may have made with the project as Purple Emperor A.iris species co-ordinators for the Hertfordshire & Middlesex Branch of Butterfly Conservation. For many years we have both had a special interest in butterflies, some of the many creatures now in serious decline, but nothing could have been more rewarding than to have found such a splendid butterfly as the Purple Emperor A.iris still to be present in some of our woodlands. Our first encounters with Hertfordshire’s A.iris in 1999 have led us to spend July of the last three years searching out the species in any likely spot. Having spent so much time walking various woods in all seasons looking for suitable habitat, it became clear that A.iris had survived in Hertfordshire through chance rather than by any directed actions. So the project took on a wider scope in Hertfordshire of achieving a better understanding of A.iris and its habitat needs, and encouraging suitable woodland management. Since 1999, we have managed to find A.iris at six locations in two 10km squares. We have also observed territorial activity at five of these locations, and it may be the first time that the discovery of such activity has been reported in Hertfordshire. We have also encouraged others in the search for A.iris in woods with public access, such as led to the finding of a territory at Tring Park by Brian Jessop in 2002, and making more observations in Broxbourne Wood Nature Reserve where Lissa Smith first had sightings in 2001. These field observations have been strongly backed by our habitat surveys and assessments, and in our view this is the only way that validated and realistic suggestions can be fed back into the woodland management process to the benefit of A.iris in Hertfordshire. Luckily, Butterfly Conservation had just published the following (see 10.6 for more details), so we have found ourselves attempting to address ready made objectives as best we could using our own resources: • Purple Emperor A.iris Species Action Plan (Bourn & Warren 2000) ~ SAP • Regional Action Plan, Thames Region, as it relates to A.iris (Clarke & Bourn 2000) ~ RAP We have also put much of our personal time and effort into raising awareness amongst those concerned with woodland management as to the presence and needs of A.iris, for example by sending out information packs and arranging site visits. A.iris is the only high priority species in the region, nominated as such by Butterfly Conservation, that has been recorded in each of the last four years in Hertfordshire and that is known to have several colonies in the county. As such, and by our efforts, the species is now to be considered as an Hertfordshire Biodiversity Action Plan Species. However, the project is only just getting underway and we feel that there is still much to be learnt and done. We would like to thank the following (see also Section 2.1 for contributors and 11 for references): • All woodland owners and managers who have been helping with the project • The increasing number of observers, many of whom have contributed to this report (2.1) • Brian Sawford for his positive approach to records of A.iris in The Butterflies of Hertfordshire • All those who have contributed to this report and/or allowed us to use their work • All those organisations, and their staff, who have been helping with the project • Ken Willmott for his various informative publications on A.iris • John Murray ~ Hertfordshire & Middlesex Branch of Butterfly Conservation Annual Butterfly & Moth Reports • Lynda Alderson, Rothamsted Research, and Richard Barker, Royston (Iceni) Weather Station, for the provision of meteorological data Please note ~ A.iris can be seen in at least two Hertfordshire woods where there is open public access. We believe there may be a few more colonies still to be found, so anyone interested in A.iris has every chance to contribute to the Hertfordshire project. However, positive management in private woodland is also essential to the success of the project, and this can only be achieved by respecting any wish regarding site confidentiality. Apologies are made in advance for any errors or omissions in this report. 2 2.1 ~ Contributors We would like to thank the many people who have helped in so many ways with this project, such as: watching for A.iris ; writing sightings reports both recent and historic; giving information that has helped with the study; for museum collection and literature searches; for allowing access to private woodland; and for considering positive habitat management. We hope that all