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2006 BUTTERFLY REPORT ROB PARKER 2006 was the hottest year ever for most of Britain, yet the arrival of spring was retarded, and most of our resident butterflies made a poor showing. On the other hand, White Admirals and White-letter Hairstreaks both flourished, and it was an outstanding year for migrants, with an exciting invasion of Camberwell Beauty. An extended summer was followed by a golden autumn that broke many of our latest season records, with Red Admirals flying right through November and December. Weather Maximum, minimum and mean annual temperatures for East Anglia were all about 1·6 Deg C above historic averages, with most of the extra heat coming in summer and autumn (see table below). After a mild, dry winter, spring became wet, with much of the rain arriving as heavy but localized downpours. High summer temperatures persisted through a sunny summer, which then extended into a golden autumn, with continuing sun (125% of normal) and temperatures beating historic averages by an extraordinary 2·7 ºC. Despite the sun, frequent heavy rain pushed rainfall figures to 130% of normal for autumn. This period generated plenty of late sightings as butterflies lingered at nectar prior to settling into hibernation. Table 1. 2006 Weather for East Anglia Season Winter 05/06 Spring Summer Autumn

Mean Temp

Anomaly Sunshine Anomaly Rainfall



% up





4·1 8·8 17·7 13·2

0·3 0·6 2·1 2·7

180·9 425·5 680·7 397·6

108 96 120 125

85·2 153·4 157·1 212·7

59 111 101 130

Source: Anomalies are measured against the 1961 to 1990 averages Monitoring the BAP Species This year, the Dingy Skipper was not found at RAF Barnham, which is very worrying, though the colony in the King’s Forest appears to be in good health. The isolated patch of habitat in Center Parcs at Elveden still supports a small colony. The Silver-studded Blue counts went well, with the preplanned dates hitting the peak flight period in most cases. One particularly encouraging discovery at Minsmere was that one colony has spread into an adjacent field in the process of reversion from agriculture to heathland. The bell heather is now

Trans. Suffolk Nat. Soc. 43 (2007)


Suffolk Natural History, Vol. 43

in prime condition there, and the count of 193 butterflies reflects a healthy new colony. Last year’s concern at Purdis Heath and Wenhaston Blackheath was softened by stronger counts, backed by improving habitat. The White-letter Hairstreak was again rather well recorded in 2006, with 17 sightings from previously unknown sites. Over the period since 1995, records have now been made from 102 tetrads (9%), although not all of these represent established colonies, and the steady increase is a measure of recording effort as well as any spread of the species. The strong performance last year, followed by the outstanding summer of 2006 has apparently led to an encouraging situation for this species. Separate detailed accounts for each of the BAP species follow as annexes. Residents Most of our resident species had a poor to middling showing. The Holly Blue has entered a trough in its regular cycle, evident in low counts in both generations. The Small Tortoiseshell was the first butterfly of the year for many observers, yet it was unusually sparse in summer and autumn. Its relatives, Peacocks and Commas were both in short supply, whereas the Red Admiral had a remarkable year. Many appeared early in spring, confirming that good numbers had successfully survived the mild winter in adult hibernation. The summer generation was numerous, and particularly evident right through autumn taking nectar and flying on bright days despite temperatures of around 8 ºC in November. Few observers had seen Red Admirals active in December before, but records were received of 26, including several on 30th, and one on New Year’s Eve. Its cousin, the White Admiral, also had a good season, with sightings from “new” woods in summer, and a recurrence of the partial second generation phenomenon – this time at 4 separate sites. Meanwhile, the grass-feeding species were mainly seen in average numbers, albeit for a protracted flight period. The previously noted decline of Wall, Grayling and Small Heath continues to be a cause for concern, though this year declines were in abundance rather than distribution. Essex Skipper, Small Skipper and Common Blue were all noted to be thin on the ground in certain localities. The Red Admiral became this year’s most widely reported butterfly, noted from 63% of tetrads visited, whilst the Small Tortoiseshell, last year’s leader, dropped right back to 10th place. Purple Emperor It is encouraging to report that about a dozen observers saw the introduced Purple Emperors in Theberton Woods. Both sexes were present, with a maximum of 5 in view at one time. No strays turned up elsewhere, giving hope that they are at home at Theberton and have a chance of establishing an enduring colony. Migrants & Oddities 2006 was an outstanding year for migration, with unexpected species of moth and butterfly turning up, as well as reasonable numbers of our regular visitors. The invasion of Camberwell Beauty was undoubtedly the highlight, beginning in the last days of July and the first week of August, when easterly winds

Trans. Suffolk Nat. Soc. 43 (2007)



brought an influx from Poland or southern Scandinavia. The bulk arrived down the coast of Norfolk and Suffolk, with just a few in Essex. A total of 42 confirmed Camberwell Beauties were logged in Suffolk during a gentle progression inland. Some lingered several days in one garden, generally feasting on fallen fruit. A few eventually reached Cumbria, and even Northern Ireland. Some may have been counted twice, but many more will have slipped in unnoticed. Most of the sightings were from householders who do not normally participate in butterfly recording, and many keen butterfly-watchers failed to get a glimpse of one. In overall quantity and duration, the invasion was very similar to 1995 – the last “Camberwell Beauty year”. Painted Lady arrived as usual, but did not achieve outstanding numbers anywhere. Clouded Yellow appeared in good numbers, with 48 sightings, including a proportion of the pale female form helice. This year however, three knowledgeable recorders saw not the whitish helice, but the brighter lemon yellow of a Pale or Berger’s Clouded Yellow. Unfortunately, these 2 species are so similar, that differentiation is impossible without capture, and such sightings normally fall into the uncertain file. On this occasion, they were found again in September, in a field near Wenhaston, having apparently bred there. Several males were caught and positively identified as Pale Clouded Yellow – a record of national significance, which is expected to be published in 2007. Tails of the unexpected arose close to Lowestoft, when a Long-tailed Blue was found taking shelter inside an open-ended poly tunnel. Enthusiasts who turned up to photograph it initially expressed the view that it would have come in with an imported plant, but changed their opinion on discovering that the facility was used for the propagation of aquatic plants only, and that no nursery stock had been imported. Furthermore, it is an acknowledged strong migrant (despite its size), and had been common in the Netherlands at the time of the prevailing easterly winds. July also brought three widely spaced sightings of Silver-washed Fritillary, another species alien to Suffolk. All of these were confidently identified, and two were photographed. None was in typical woodland habitat, and all appear to be strays, in a year that has seen a nationwide surge in sightings of this large fritillary. A single female Dark Green Fritillary also put in an unexplained appearance at Wangford Warren on 1 Jul. The only Swallowtail of the year was seen north of Woodbridge. There was also a single Large Tortoiseshell, on elm in Waldringfield on 3 Aug. One confirmed, but unexplained, Chalkhill Blue turned up at Ipswich Golf Course on 10 Aug. Additionally, Bath White and Marbled White sightings were noted as unconfirmed possibles in this remarkable year. Early/Late Records Spring brought only one earlier-than-ever record; an extraordinarily early Small Copper on 27 March. The golden autumn, on the other hand brought a surge of later-than-ever records: Grayling 1 Oct, Small Heath 13 Oct, Small White, Green-veined White, Holly Blue and Speckled Wood all on 5 Nov. Red Admirals were active on sunny days throughout November; and 26 sightings were logged in December, the last (another latest-ever record) on New Year’s Eve.

Trans. Suffolk Nat. Soc. 43 (2007)


Suffolk Natural History, Vol. 43

Geographic Coverage Records were received from 522 tetrads, which is better than 2002–2004, but does not quite match 2005’s high of 530. Over 200 regular recorders contributed.. Our distribution maps are improving as an increased number of observers record butterfly numbers, rather than simply presence. Species Maps Distribution Maps for individual species have been prepared for our 31 regulars, and these are available for reference as required. This year’s unusually high species count stands at 40 including the introduced Purple Emperor and the unexpected irregulars noted above (but excluding the unconfirmed Bath White & Marbled White). The average number of species recorded per tetrad dropped from 10 in 2005 to 8·9 in 2006, reflecting a generally poor year for the widespread species. Analysis Relative scarcity can be deduced from a count of the number of tetrads from which each species has been recorded. Figures for 2005 and 2006 are given in Annex A, and are also shown as a percentage of the recorded tetrads. This year’s league table begins with the unexpected migrants merging with our BAP species. The White Admiral and White-letter Hairstreak have both done rather well, whereas the Small Tortoiseshell is no longer our most widely distributed butterfly. Worryingly, the decline of the Wall continues, and it was found in only 6·3% of the squares surveyed. The change from last year to this is expressed in the “c.f. last” column, and it can be seen that most species had a reduced distribution this year. Trends over a longer period are presented separately at Annex B. Distribution mapping does not assess a butterfly’s abundance at its breeding site as accurately as the “index” derived from transect walks. Generally, a fall in index figures will be detected prior to a diminishing distribution. Transects New transects were started this year at Alton Water, Coddenham Manor Farm, Combs Wood, Fressingfield Tythe Farm, Landguard, Ramsey & Hintlesham Wood, bringing the total to 18 full transects – better coverage than ever before. The amalgamation of existing arrangements to create the UK Butterfly Monitoring Scheme adds a new dimension to national butterfly monitoring, allowing population variations to be estimated alongside distribution data. Special thanks are due to all our transect walkers for their commitment to regular monitoring at: North Warren (Rob Macklin), Fynn Valley (Richard Stewart), Minsmere (Robin Harvey), Bradfield Woods (Steve Hunt), Center Parcs (Graham Hersey-Green), Cavenham Heath (Michael Taylor), Walberswick (Adam Burrows), Spring Lane (Rob Parker), Combs Wood (Liz Cutting), Ramsey/ Hintlesham & Wolves Wood (Mark Nowers), Newsons Farm (Frances Bee), Barham picnic site (Nick Dickson), Upper Abbey Farm (Trudy Seagon), Alton Water (Simon Waters), Manor Farm (Claire Studman), Tythe Farm (Peter Vincent), and Landguard (Dave Burgess).

Trans. Suffolk Nat. Soc. 43 (2007)



Annex A. Scarcity for 40 species seen in Suffolk in 2006. Tetrads per Species – 2005 & 2006. (Species listed in order of scarcity in 2006). % of 500 Tetrads Species tetrads 2005

0 ·2 0 ·4 0 ·0 0 ·0 0 ·8 3 ·4 0 ·2 7 ·8 4 ·4 8 ·6 6 ·4 9 ·2 2 ·6 7 ·6 10·6 18·8 21·4 27·0 32·6 56·2 24·2 28·8 48·8 35·8 37.6 60·4 66·8 19·0 60·4 49·8 53·4 63·4 63·2 61·4 58·8 57·0

1 2

4 17 1 39 22 43 32 46 13 38 53 94 107 135 163 281 121 144 244 179 188 302 334 95 302 249 267 317 316 307 294 285

Dark Green Frit. Long-tailed Blue Chalkhill Blue Large Tortoiseshell Purple Emperor Swallowtail Pale Clouded Yellow Silver-washed Frit. Dingy Skipper Silver-studded Blue Camberwell Beauty Wall White-letter Hairstrk Green Hairstreak White Admiral Purple Hairstreak Clouded Yellow Grayling Brown Argus Small Heath Essex Skipper Small Skipper Brimstone Holly Blue Large Skipper Small Copper Orange-tip Ringlet Common Blue Green-veined White Small Tortoiseshell Painted Lady Peacock Gatekeeper Comma Small White Large White Speckled Wood Meadow Brown Red Admiral

Tetrads % of 522 Cf Remarks tetrads last* 2006 1 1 1 1 1 1 3 3 4 15 30 34 35 36 39 43 51 52 84 93 96 144 149 155 156 162 182 185 187 188 223 232 232 234 242 256 260 267 304 324

0 ·2 0 ·2 0 ·2 0 ·2 0 ·2 0 ·2 0.6 0 ·6 0 ·8 3 ·0 5 ·9 6 ·7 6 ·9 7 ·1 7 ·7 8 ·5 10·1 10·3 16·6 18·3 18·9 28·4 29·4 30·6 30·8 32·0 35·9 36·5 36·9 37·1 44·0 45·8 45·8 46·2 47·7 50·5 51·3 52·7 60·0 63·9

unexplained rare migrant unexplained 0·99 0·49

0·99 0·87 29·59 0·86 1·57 0·83 1·20 0·92 3·87 1·35 1·56 0·98 0·88 1·05 0·90 0·54 1·27 1·11 0·74 1·02 0·98 0·61 0·66 2·41 0·76 0·93 0·89 0·80 0·81 0·86 1·02 1·12

introduction rare migrant vagrants precarious less casual sight’gs good migrant yr decline new sites found expanding good migrant yr numbers low good year declining poor year

entering a trough

wet spring

poor year very poor year good migrant yr weak showing

remarkable yr

40 species seen in Suffolk in 2006 (including introduced Purple Emperor) *cf last indicates the proportion of last years cover achieved in current year.

Trans. Suffolk Nat. Soc. 43 (2007)

Suffolk Natural History, Vol. 43


Annex B. ANALYSIS - 1995 to 2006 A measure of Abundance – for residents and regular visitors Survey from: to:

2000 2004

2001 2002 2005 2006 2003 2004 2005 2006

Period: Tetrads:Species/Tetrad:

5yrs 878 11·9

5yrs 5yrs 1yr 1yr 865 864 448 530 11·8 12 9·4 8·4

1yr 1yr 500 507 10 8·7

Tetrads from which recorded Small Skipper Essex Skipper Large Skipper Dingy Skipper Clouded Yellow Brimstone Large White Small White Green-veined White Orange Tip Green Hairstreak Purple Hairstreak White-letter Hairstreak Small Copper Silver-studded Blue Brown Argus Common Blue Holly Blue White Admiral Red Admiral Painted Lady Small Tortoiseshell Peacock Comma Speckled Wood Wall Grayling Gatekeeper Meadow Brown Ringlet Small Heath

261 240 228 7 192 249 579 576 520 401 83 109 43 297 20 160 327 370 36 538 410 538 468 403 535 200 107 495 582 334 195

290 253 259 7 87 290 617 622 572 455 85 112 54 310 20 169 367 476 46 571 396 615 527 457 572 183 107 524 615 378 205

Notes: Rare migrants excluded

Trans. Suffolk Nat. Soc. 43 (2007)

322 267 295 8 111 317 599 606 552 439 88 120 70 341 20 193 383 419 61 577 448 621 532 475 565 163 107 504 591 397 209

114 88 90 5 40 100 251 245 203 151 29 40 25 141 18 82 156 82 17 288 275 289 219 221 245 83 52 194 235 150 93

121 102 90 7 36 106 283 293 257 199 31 37 13 160 11 65 164 185 13 225 143 332 231 198 270 66 34 248 291 161 93

135 107 121 4 13 163 316 317 302 244 43 46 22 144 17 53 188 281 32 285 95 334 302 267 307 39 38 249 294 179 94

Trend 144 96 156 4 51 149 260 256 188 182 36 43 35 162 15 84 187 155 39 324 232 223 232 242 267 34 52 234 304 185 93

precarious strong year

strong recording

serious decline



Annex C . Annual Report on Silver-studded Blue for 2006

Season Despite another cool, wet May, the butterfly was on the wing from 14 June. The subsequent hot July allowed unhindered survey effort and produced a high overall count, generally at peak population dates. The protracted heat apparently encouraged the dispersal habit, and towards the end of the season, strays were found at a number of site extensions. Survey Results The total count of 5470 might sound high for a scarce butterfly, but this rather masks less satisfactory colony strengths in several places. Mini transects at Martlesham Heath and Minsmere assisted local management, and confirmed timing for the main counts. The results for the season’s counts are tabulated below, and are very encouraging. The recently established colonies at Parsnip Plantation and Rushmere Heath have again shown a gentle increase in numbers. A major good news story emerged at Minsmere, where one of the reversion fields is now well covered with pioneer heather, and has been colonised by Silverstudded Blues from the adjacent “Football Pitch” area. No less than 193 were counted there on 4 July, adding an excellent new colony, and leading the way for future heathland re-creation plans. A spread across a road has also been 2006 Count Map

14 Tetrads

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Suffolk Natural History, Vol. 43

noted at Lower Hollesley C, and this is shown as a fresh colony on the table. At Upper Hollesley, there has also been spread into the SHDC area where heather has been cut. Even the small area of translocated heather surrounding the lagoon at the Ransomes industrial estate has attracted butterflies in its first season, though it remains to be seen whether these will stay to breed on that margin. The distribution map for the 2006 counts shows records from 14 tetrads, and is reproduced below. Such a map does not reveal the condition of each site or its butterfly colony. In general, the larger, well-managed coastal sites are doing well, whilst the isolated inland sites are those where the colony has a weaker tenure. In 2005, three apparently failing sites attracted particular concern, and each is dealt with separately below. Two satisfactory common themes are that butterflies were still present this year, and that appropriate steps are being taken to recover suitable habitat. Purdis Heath In his 2003 report to SWT, Neil Ravenscroft warned that the over-mature condition of the heather, the low proportion of Erica, and the absence of ant colonies all presented grounds for concern. A site visit in September 2005, following the population crash, confirmed the very low density of Lasius ants around the former prime site, and stepped up the forage harvesting programme, creating an enlarged area of pioneer heather for egg-laying, with bare ground for the ants. This year’s extensive survey work confirmed the absence of Silver-studded Blues in the former flight area, but did find a total of 25 spread across 3 separate areas of the heath. The best of these lies on a slope cleared of bracken, where the heather is now about 15cm high. Recently foraged strips with some re-growth of Erica were also attracting a few females, and others were flying in the south of the site over an area burnt out about 7 years ago. A further site meeting, led by English Nature, established that the present owners were content for Ipswich Golf Club to continue cutting the heather and for Greenways to stage further volunteer work parties to control scrub. Plans for winter 2006/7 include further cutting, including part of the former flight area. Martlesham Heath The count of 280 is down on last year’s 377, but was conducted in windy conditions. A major summer fire in the north of the heath has destroyed trees, but did not have much impact on the flight areas. The area in need of management is enormous and beyond the resources of the Martlesham Conservation Group. An English Nature-led site meeting established where funds might best be used. A preliminary cut of bracken is planned in the (privately owned) airfield area, followed by forage harvesting and bracken control. A draft management plan has been drawn up with the assistance of English Nature. Wenhaston Black Heath The count of 24 SSB late in the season, at our most northerly and somewhat exposed site, is encouraging, following a three-year period when the population has been barely detectable. Heather cutting to extend the area of pioneer heather may have paid off, as some females were seen beyond the traditional flight area. Habitat work by the Wenhaston volunteer group will now benefit from a grant, which has allowed the purchase of a forage harvester.

Trans. Suffolk Nat. Soc. 43 (2007)



Monitoring The results of the 2006 counts are summarised below: 2006 COUNTS Monitored Silver-studded Blue Sites listed geographically from the North Location

Grid Ref.



Blackheath Wenhaston Walberswick Comn NNR Aldringham Walks Westleton Heath NNR Westleton Common Westleton Football Pitch Minsmere Foraged Square Minsmere Reversion Field Minsmere Sawmills Minsmere Football pitch Minsmere Natterjack pond Minsmere SW Comp 1 Minsmere Pit Comp2 Minsmere SE Comp 3 Minsmere Comp 20 N Minsmere Comp 20 S Minsmere S Comp3 Minsmere Central Comp 3 Minsmere Powerlines Minsmere North Bridleway Minsmere Potbriggs Minsmere North Grimstones Minsmere E Comp 13 Minsmere Comp 13 track Minsmere Comp13 Tanktrap Dunwich Heath Gravel Pit Upper Hollesley MOD Lower Hollesley ‘A’ Lower Hollesley ‘B’ Lower Hollesley ‘C’

TM420749 TM491752 TM464612 TM4569 TM44306870 TM44406880 TM459689 TM451689 TM452692 TM451691 TM451693 TM450694 TM457692 TM457691 TM446683 TM445680 TM456693 TM453693 TM461683 TM468687 TM468689

30.07 23.07 04.07 23.07 03.07 03.07 04.07 04.07 01.07 01.07 04.07 04.07 04.07 04.07 04.07 04.07 04.07 04.07 04.07 04.07 01.07

Richard Havard Adam Burrows Rob Macklin Adam Burrows David Rous David Rous Mel Kemp Mel Kemp Mel Kemp Mel Kemp Mel Kemp Mel Kemp Mel Kemp Mel Kemp Mel Kemp Mel Kemp Mel Kemp Mel Kemp Mel Kemp Mel Kemp Mel Kemp

TM462688 TM468681 TM464681

01.07 Mel Kemp 04.07 Mel Kemp 04.07 Mel Kemp

Rushmere Heath Martlesham Heath Parsnip Plantation Ipswich Golf Club, Purdis Purdis Heath Industrial Estate Ind. Est. lagoon fringe

14 25 106 127 302 20 2 120 766 252 29 14 392 163 57 0

0 0 106

10 24 12 37 48 154 37 164 63 365 2 22 1 3 73 193 328 1094 81 333 10 39 9 23 249 641 79 242 23 80 0 0 0 0 0 0 0 0 42 148

545 0 0

212 0 0


757 0 0

TM466683 04.07 Mel Kemp 0 0 0 TM468687 0 TM449669 04.07 Mel Kemp 23 13 36 TM33344723 03.07 David Mason 58 18 76 TM342465 03.07 Richard Stewart 202 69 271 TM343461 03.07 Richard Stewart 193 41 234 TM352458 03.07 Nick Mason 48 7 55 TM350456 28.06 David Mason 9 1 10 TM202448 16.07 Jeff Higgott 8 2 10 TM2445 9&11.07 Phil Smith not split 280 TM32724579 03.07 David Mason 18 18 TM207415 06.07 Neil Sherman 0 1 1 TM21204270 06.07 Neil Sherman 18 7 25 TM207419 20.07 Julian Dowding not split 127 TM207415 20.07 Julian Dowding not split 8 2006 Totals: 3617 1438 5470

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Suffolk Natural History, Vol. 43

Annex D. Dingy Skipper Survey, 2006 SUMMARY The 2006 survey was a mix of good and bad for our Dingy Skipper colonies. The colony in the archery area of King’s Forest was again found to be flourishing, but the Barnham colony may have been extinguished. Other sites checked were all in line with 2005 results. The butterfly was on the wing by 12 May, just 2 days after it had appeared on the Devil’s Dyke in Cambs. The unusually wet month of May again had a disruptive effect on our monitoring effort, but the flight period continued until 8 June in the King’s Forest, with one straggler still flying on 13. All visits were conducted with the landowner’s consent, or along public rights of way. A total of 9 sites were visited during the 2006 flight period. Dingy Skippers were found only at the established sites, including an isolated, but stable colony at Center Parcs. The butterfly appears to be losing ground, even within its very limited domain in the Suffolk Brecks. This year, it was recorded from only 3 tetrads. Other UK counties are known to have experienced a poor year for both the Dingy Skipper, and its larval host plant (Bird’s-foot trefoil). The sites visited are listed individually below, as main, defunct or for future investigation. MAIN COLONIES RAF Barnham [TL8580/8680] – Three visits were made to the Barnham Training Area, but not a single Dingy Skipper was seen. The first check was a thorough search of the normal flight area, made on a cool overcast 19 May. This revealed that the sheep had not returned to grazing, and the protective fence had not been completed, though the posts had been erected. The bird’sfoot trefoil was growing again after last year’s grazing, but was not at that time in flower. A similar negative search was made on 25 May, as the wet weather continued. At last, in ideal weather, a further survey was conducted on 8 June, but again, none were found, although they were flying that day in the King’s Forest. This gives cause for serious concern, at what ought to be our strongest colony, which is now looking more like a defunct site. King’s Forest (Wordwell) [TL834732] – This site recorded a maximum count of 12 on 23 May, and again the Dingy Skippers were flying further to the south and west than the main ride. The plantation to the north west of this area has been clear felled in recent months, partially opening a route between the Wordwell ride and the Archery site, although this is unlikely to become hospitable to Dingy Skippers in the short period of re-growth. King’s Forest (Archery) [TL831737] – The area used for archery practice, part of which is kept mown, had Dingy Skippers by 12 May. On 14 May, a party of 13 volunteers found 20 flying. Although this was less than last year’s exceptional count of 107, the butterflies were well spread around the rides, and the colony is clearly healthy. The rough area at the southern edge of the mature forest had less bird’s-foot trefoil, but more butterflies than the mown areas. Subsequent visits by a variety of recorders found Dingy Skippers flying until 13 June.

Trans. Suffolk Nat. Soc. 43 (2007)



King’s Forest (Chalk Lane) [TL827752] – Several recorders found a few Dingy Skippers along Chalk Lane, on the parallel track to the north, and at the heathland regeneration area. The tree felling discussed with the Forestry Commission has not yet come to pass. None of the 2004 records of strays further east and north were reproduced, despite several independent searches. Elveden (Center Parcs) [TL810805] – A visit on a cool, overcast 19 May found just one Dingy Skipper flying and staff revisiting subsequently saw 3, confirming that the colony is still active. The area mown as the bird walk is being managed with the Bird’s-foot trefoil in mind. It was recommended that some of the gorse be cleared and that the bare soil area of the drainage ditch needs to be cleared of self-seeded trees, which are creating unwanted shade. DEFUNCT SITES King’s Forest (John O’Groats Cottages) [TL818737]. This area, and the sector to the north of it, contains a number of isolated patches of bird’s-foot trefoil growing in sheltered rides. Two unexpected sightings in the TL818758 vicinity give hope that they may have re-colonized. This area becomes a priority for further survey work in 2007. Kings Forest South [TL7872/8073/8272SW] – Not specifically targeted this year, but no casual records received. Barnhamcross Common [TL864811] – This site lies adjacent to RAF Barnham, and occasional strays are seen on the south edge of Barnhamcross Common, which lies in administrative Norfolk, but in Suffolk’s biological recording area. Two visits were made to the southern margin, but no Dingy Skippers were found. This is hardly surprising, given the absence of activity on RAF Barnham. Marmansgrave Wood [TL8480] – One negative search along the footpath confirmed the view that this former site may be considered defunct. OTHER SITES (for future searches, but not checked in 2006) Sketchfar [TL836801] – The sheep-grazed area in the Elveden Estate’s Sketchfar domain has one promising looking corner, which deserves a visit next year. It lies close to the defunct site at Marmansgrave Wood. Euston Quarry [TL896775] – This wonderful CWS has everything that ought to make a good Dingy Skipper site, including Bird’s-foot trefoil and a Common Blue colony. It was not checked this year. Cut-off Channel [TL7386] – During Norfolk’s 2004 survey for Grizzled and Dingy Skipper, both were found along the watercourse known as the Cut-off channel, which has a chalky double embankment along a nine mile stretch in Norfolk. Visits to the Suffolk stretch were made on 12 May (after finding DS flying in nearby Norfolk), but there was a shortage of Bird’s-foot trefoil, and nothing was seen. Thetford Rifle Range [TL8480] – This MoD site lies in Administrative Norfolk, but is in Suffolk’s biological recording area. It has plenty of Bird’s-foot trefoil in a suitably sheltered area, and was walked extensively in 2005. Although the habitat looked excellent, it was disappointing not to find any Dingy Skippers.

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Suffolk Natural History, Vol. 43

Annex E. White-letter Hairstreak – 2006 The White-letter hairstreak has been accepted as a Suffolk BAP species, and the Species Action Plan is awaiting publication. At national level, the future for the White-letter Hairstreak is viewed with some concern largely because of the uncertain consequences of Dutch Elm Disease. The recently published “The State of British Butterflies” presents its ten-year population trend as a loss of 63% in Britain. In Suffolk, we have been working so hard to unearth surviving colonies of this previously under-recorded insect, that distribution figures appear to show a substantial increase. Analysis shows that the number of tetrads occupied by White-letter Hairstreak has increased from 40 to 102 since the Millennium survey, but this apparent spread must be treated with caution. On the one hand, the butterflies are showing some adaptability in leaving elms infected by the disease, and they are moving on to younger suckers elsewhere. This adaptability could be an effective survival mechanism, but it also leaves dots on distribution maps at sites not permanently colonised, and is thus misleading. Our volunteer recorders are also becoming more skilled at finding small colonies at the same time as the butterflies are becoming easier to find due to lower elm canopies and successive hot summers. That said, the White-letter hairstreak was recorded from 35 tetrads in 2006, including observations from no less than 17 fresh squares. This brings the total to 102 tetrads in which it has been found at some time in the last 12 years (a remarkable 9·3% of all tetrads). It is clear that the butterfly is surviving at many small sites spread across the county, many of them no more than a stretch of roadside elm hedge. Future monitoring will include participation in a nationwide initiative, which has been launched at: Rob Parker 66 Cornfield Road Bury St Edmunds Suffolk IP33 3BN

Trans. Suffolk Nat. Soc. 43 (2007)


Rob Parker

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