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2012 BUTTERFLY REPORT ROB PARKER 2012 was wet, wet, wet, resulting in a good season for moss, algae and slugs. It was not so good for butterflies, and the verdict of most of our all-species transects showed it to have been the worst year for the past ten (or more) years. Like the previous year, it was a very confused season, but in a very different way, as we had no earliest or latest-ever records. Instead, the season was simply awful for most butterflies and observers alike. Our more widespread species were thin on the ground, and annual indices were lower than usual. There were very few migrants and the total species count was down at 33. On the other hand, the extra rain made the grass grow nicely and all of “the Browns” put in a strong enough performance. There was another silver lining too. The Silver-washed Fritillary continued its expansion and bred successfully in new woods. Good recording effort again resulted in decent coverage in the third year of the current five-year period. Annexes A & B provide analysis of the season's results and allow comparison with previous years. Weather A generally mild winter turned to drought in time for the announcement that a hosepipe ban was essential to refill reservoirs after two dry seasons, but this seemed laughable as we then experienced unusually high rainfall in spring, summer and autumn (see the table below). As usual, the averaging hides the spells of very heavy localized downpours, but it can be seen that spring and summer were cloudy, trending to cooler than average in autumn. It was the cloudy and wet nature of the season that had the most significant impact on butterflies. Although the grass grew well, and our grassland butterflies did rather better than usual, most other species suffered from the lack of warm sunny days in which to fly and mate. By the end of the year the aquifers had been replenished and the water table was high, but our butterfly counts were low. Table 1. 2012 Weather for East Anglia Season Winter 11/12 Spring Summer Autumn
Mean Temp
Anomaly Sunshine Anomaly Rainfall Anomaly
Deg C
Deg C
hrs
%
mm
%
5 9∙2 16∙1 10∙3
0∙7 0∙2 -0∙3 -0∙6
221 464 509 355
119 99 86 109
118∙8 195 253∙9 203∙8
81 143 158 114
Source: www.metoffice.gov.uk/climate/uk/2012. Anomalies are measured against the 1971 to 2000 averages [as last year].
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Residents - Winners & Losers A proportion of early sightings were Small Tortoiseshells and others emerging from hibernation in the few fine days at the end of February, but there was then a pause until 23 March when it suddenly became warm enough for the Peacocks, Brimstones, Commas and a few Red Admirals to appear across the county. Most garden recorders noted less butterflies than usual, particularly when commenting on the whole season. As last year, Common Blue, Essex and Small Skippers, had a poor year. Green Hairstreak and Orange-tip appearances were limited by the wet spring weather, and sixteen of our regular species were found in less than the tetrad count achieved in 2011 – itself a poor year. The Common Blue spring brood arrived late, and was very thin on the ground, whilst its summer brood was also later than usual, and erratic, generally thin, but with a few sites producing good showings. Other double brooded species were also affected, Brown Argus and Holly Blue were both weak, whereas the Small Copper recovered somewhat in its second generation. See Appendix A for a species by species comparison. Early & Late The humdrum weather resulted in a late spring and a cool, wet autumn, so that not a single earliest or latest-ever species record was broken. Monitoring the BAP Species There are seven Suffolk BAP species, including two in the “for study only” category. Silver-studded Blue The annual count was again mistimed; the emergence times fell back to those we used to expect ten years ago, confounding our expectations of another early year. We assembled a strong team, but once again we missed the peak – this time arriving too early. We returned a week later to find the numbers much closer to the peak, but the second count was curtailed by heavy rain and we had to abandon the afternoon counts. As a result, totals look low, but this is largely down to the number of sites we failed to visit. Only 16 out of a total of 47 compartments were adequately counted, seeing a total of just 1270, compared with 4542 last year. (See Annex C for full results). The colony translocated to Blaxhall Common in 2007 was again strong, with a record high one day count of 48, and the first sighting of a Sliver-studded Blue on the south side of the road. On the other hand, it was distressing to discover that not a single Silver-studded Blue was seen at Walberswick NNR, despite repeated visits during the flight period. That colony could be lost. Continuing habitat restoration at Purdis Heath by a team of local volunteers is a cause for satisfaction, and a single species transect will be properly established there for 2013. Dingy Skipper The Dingy Skipper was not found at Center Parcs or RAF Barnham, but the adjacent areas on the fringe of Thetford Forest and in the NWT reserve on Thetford Heath were both active, and a mating pair was seen on the latter
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site. It is encouraging that the Dingy Skipper is clinging on in this area. In the King’s Forest, they are still breeding around the archery site and a few were seen scattered into the Chalk Lane area, where extensive felling has altered the appearance of the forest. See Annex D for more detail. White-letter Hairstreak This was one of the species that suffered from the wet summer. It was difficult to find many at the known strong sites, and many visits were fruitless in marginal weather. It was recorded from only 17 tetrads compared to 26 last year. See Annex E for more detail. White Admiral The White-Admiral also had another good season, being seen in 47 tetrads, including sightings from woods not previously known to house colonies. To some extent, this good result was down to our vigorous search of woodland for Silver-washed Fritillary. The colony in Bradfield Woods has now been present for eight consecutive seasons, and transect counts were at an all time high. See Annex F for more detail. Grayling Over the past four years, the Grayling population has remained stable in about 10% of tetrads, although a decline since the Millennium survey has been evident, particularly in the west. This year it was seen in good numbers at several of its Sandlings sites. See Annex G for more detail. The UK BAP list includes two study species for enhanced monitoring. In both cases, Wall and Small Heath, the larval host plant is grass:
Wall The Wall is in decline in the UK and in Suffolk, and a two year single species survey was undertaken in 2011/2012. The results have sadly confirmed the severity of the decline in Suffolk. A particular cause for concern is that our strongest population lies along the sea wall between Bawdsey and Shingle Street, where it faces disturbance from essential work on the sea wall in 2013 and more disruption later from the construction of the landfall site at which the cables from an offshore wind farm will come ashore. Results from the 2011/2012 Wall survey are to be found at Annex H. Small Heath This is in a much less critical situation than the Wall, indeed it seems to have benefited from the wet season, and was found in 25% of our tetrads this year. Even so, it has lost ground on farmland amongst fertilized grass. Its performance since 1995 can be judged from the table at Annex B. Purple Emperor The introduced Purple Emperors were still flying in Theberton Woods, although sightings were fewer this year. It is understood that some 2011 larvae were overwintered indoors and released this July ahead of the emergence of totally wild stock. There were no sightings from elsewhere in 2012.
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Migrants 2012 was a bad year for migration, with very few Painted Lady sightings in June, and only one Clouded Yellow all year. Only at the end of August and in the first week of September did we have a small scale immigration of Red Admiral, Painted Lady and Large White, probably accompanied by a few Small Tortoiseshell. In the final analysis, Painted Lady reached marginally more squares than it had done in 2011, and there were enough Red Admirals in autumn for us to feel they had had another good year. Silver-washed Fritillary The silver lining to this gloomy year was the continued spread of Silverwashed Fritillary. Pakenham Wood became the scene of great enthusiasm when visitors were able to count 20 or so cruising around the clearing over the public footpath. One observer saw three mating pairs, and his photograph of one pair included a third Silver-washed flying through the viewfinder. A summary of its status published in Suffolk Argus (Autumn 2012, p.5/6) gave the tally of woods in which it has been found as 17, not counting four which received a single brief sighting in 2011. It is definitely breeding in at least five of these, and we can hope that it has returned to Suffolk as a resident species. Unusual Species After last year's freak flurry of non-resident species, 2012 was back to normal, with a total species count of just 33. The only oddity was Marbled White which was again found in Landseer Park. Perhaps that population, presumably an unauthorized introduction, has taken hold; in any event, this year it had spread the short distance to the adjacent tetrad (still within Landseer Park). There were also three unexpected sightings of single Marbled Whites spread across the east of the county. Unusually, there were no Swallowtails this year. Recording and Geographic Coverage Good recording effort in the 3rd year of the current five year period brought our cover up to 890 tetrads (out of 1089). The results of BC's “Big Butterfly Count” were selectively incorporated. This is an exercise in popular science, with many novice recorders recording one location, so the contribution was mainly common species, in a few cases from tetrads that were previously “black holes”. The Big Butterfly Count has stirred fresh enthusiasm, and we have recruited a number of new recorders. The residual black holes and under-recorded areas are scattered across the county with the weakest area remaining the agricultural land in High Suffolk. Species Maps Distribution Maps for individual species have been prepared for our 31 regular species, and these are available for reference as required. The average number of species recorded per tetrad was just 9 for 2012, and stands at 11∙5 for the current five year period.
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Analysis The species that put in an appearance this year are shown in Annex A, in order of scarcity, with a direct comparison to last year’s turnout. The wet season advanced Meadow Brown five places into the most common position, pushing Red Admiral back to second. Meadow Brown is generally accepted as Europe's most common species, so this is very apt. Red Admiral, on the other hand, is certainly not our second most abundant butterfly, but is large and easily recognized which means it never gets overlooked by garden recorders. Further up the table, the flourishing Silver-washed Fritillary has this year overtaken the flagging Wall. Trends over a longer period are presented separately at Annex B for our 31 regulars. The latest rolling five year figures cover 997 tetrads, and for most species, the long term distribution trend is reflected in the single year figures. However, this is not always the case. The Common Blue, for example, had a poor year in 2012 (found in 25% of tetrads recorded), although its position appears stable in the five year columns (found in 50% of the county). To those thinking about long-term declines, the table at Annex B merits close study. Transects Analysis of transect results gives a sharp view of trends, and 2012 results have been the weakest-ever, with most individual transects recording their all-species counts as lowest ever, or lowest for the last ten years. The 19 full transects walked this year all produced poor scores for Small/Essex Skippers and particularly poor for Common Blue. Small Heath and Grayling are not present at many sites and these reflected mixed results. Small Heath actually did well at North Warren and Walberswick, despite long term declines nationally. New transects at Knettishall Heath and Purdis Heath will come on line in 2013. Thanks are due to the following, who put in dedicated monitoring effort at: North Warren (Dave Thurlow), Minsmere (Robin Harvey/Katy Smith), Bradfield Woods (Steve Hunt), Center Parcs (Graham Hersey-Green), Cavenham Heath (Michael Taylor), Walberswick (Will Russell), Spring Lane (Rob Parker), Ramsey/Hintlesham and Wolves Wood (Mark Nowers), Newsons Farm (Frances Bee), Upper Abbey Farm (Trudy Seagon), Alton Water (Simon Waters), Manor Farm (Brenda Hudson) , Tythe Farm (Peter Vincent), Dunwich Forest 1&2 (Dayne West), Arger Fen (Gordon Kennett), Black Heath (Linda Hammond) and Nowton Park (Fay Jones). Single-species transects for Purple Hairstreak (Steve Hunt) and Silver-studded Blue (Terry Peake) also produced useful results. In almost every case, additional volunteers (not named individually) assisted the lead walker. The Combs Wood transect remains vacant and awaiting a volunteer walker.
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Annex A. Scarcity for 33 species seen in Suffolk in 2012. Tetrads per Species – 2011 & 2012 (Species listed in order of scarcity in % of 678 Tetrads 0∙1 0∙1 0∙3 0∙3 1∙6 0∙4 0∙6 0∙1 2∙2 3∙8 4∙6 2∙4 9∙1 4∙7 7∙1 17∙8 10∙6 12∙4 11∙7 17∙4 28∙6 29∙1 32∙4 21∙8 27∙7 24∙9 45∙9 40∙7 54∙0 42∙0 33∙3 53∙5 45∙4 47∙6 61∙8 56∙0 66∙7 53∙1
1 1 2 2 11 3 4 1 15 26 31 16 62 32 48 121 72 84 79 118 194 197 220 148 188 169 311 276 366 285 226 363 308 323 419 380 452 360
Species Long-tailed Blue Queen of Spain Frit. Dark Green Frit. Swallowtail Clouded Yellow Purple Emperor Dingy Skipper Marbled White Silver-studded Blue White-letter Hairstrk Wall Silver-washed Frit Green Hairstreak White Admiral Grayling Brown Argus Purple Hairstreak Painted Lady Essex Skipper Small Heath Common Blue Brimstone Holly Blue Small Skipper Large Skipper Small Copper Orange-tip Small Tortoiseshell Green-veined Wht Peacock Ringlet Speckled Wood Comma Gatekeeper Small White Large White Red Admiral Meadow Brown
Tetrads % of 575 *cf last None None None None 1 1 3 5 13 17 23 24 30 47 47 57 61 92 94 126 145 149 158 166 168 195 210 220 260 265 288 293 305 321 334 343 369 385
0∙2 0∙2 0∙5 0∙9 2∙3 3∙0 4∙0 4∙2 5∙2 8∙2 8∙2 9∙9 10∙6 16∙0 16∙3 21∙9 25∙2 25∙9 27∙5 28∙9 29∙2 33∙9 36∙5 38∙3 45∙2 46∙1 50∙1 51∙0 53∙0 55∙8 58∙1 59∙7 64∙2 67∙0
0∙11 0∙39 0∙88 5∙90 1∙02 0∙77 0∙87 1∙77 0∙57 1∙73 1∙15 0∙56 1∙00 1∙29 1∙40 1∙26 0∙88 0∙89 0∙85 1∙32 1∙05 1∙36 0∙80 0∙94 0∙84 1∙10 1∙50 0∙95 1∙17 1∙17 0∙94 1∙06 0∙96 1∙26
Remarks
few migrants Introduced Landseer + 3 a weak count wet summer Survey plus BBC dispersal conts wet spring a good year poor year few migrants a decent year poor year poor year
a short spring
decent showing
a good year
*cf last Indicates the proportion of last year's cover achieved in the current year. 33 species seen in Suffolk 2012 (including Purple Emperor & Marbled White)
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Annex B. ANALYSIS - 2004 to 2012 Long term trends - for residents and regular visitors. Survey from: to:
2004 2008
2005 2009
2006 2010
2007 2011
2008 2012
Period: Tetrads:Species/Tetrad:
5yrs 918 12∙7
5yrs 994 13∙1
5yrs 1003 13∙4
5yrs 1003 13∙6
5yrs 993 13∙8
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
362 296 347 8 104 394 683 685 632 522 108 116 81 369 21 215 404 502 68 655 403 644 621 557 636 136 95 593 699 473 236
390 296 412 8 118 442 785 775 718 552 113 128 79 376 22 260 475 504 71 699 604 698 700 635 724 120 104 663 789 528 234
411 292 439 8 118 461 806 799 731 565 119 147 83 402 21 292 505 498 79 720 615 701 714 663 720 115 108 701 805 571 241
405 278 462 7 85 463 820 813 765 618 134 159 79 397 21 297 499 520 78 751 557 689 721 672 738 100 104 725 804 587 252
422 283 475 7 69 450 832 811 765 612 119 178 76 417 20 279 513 500 93 750 537 687 714 694 740 96 104 732 816 634 271
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Annex B. ANALYSIS – continued Survey from
2008
2009 2010
2011
2012
Period: Tetrads:Species/Tetrad:
1yr 549 9
1yr 645 10.3
1yr 575 9.7
1yr 677 8.7
1yr 575 9
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
125 99 131 2 5 157 343 305 307 236 35 33 24 145 15 38 128 197 32 289 68 241 307 300 317 28 37 281 361 246 84
169 106 199 5 57 199 469 425 392 244 41 56 16 188 17 128 249 153 26 283 447 398 408 351 411 36 54 354 434 268 100
161 88 176 4 8 195 344 384 292 266 51 66 26 190 15 111 222 231 51 320 125 282 305 299 281 27 42 326 353 250 100
148 79 188 4 11 197 380 421 366 311 62 72 26 169 15 121 194 220 32 452 84 276 285 308 363 31 48 323 360 226 118
166 94 168 3 1 149 343 334 260 210 30 61 17 195 13 57 145 158 47 369 92 220 265 305 293 23 48 321 385 288 126
Trend
Weak Migrant variable
Strong recently
Gaining Stable Gaining
Doing well Doing well Migrant variable Decline checked Strong Still doing well Serious Decline Weak but stable
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Annex C. Annual Report on Silver-studded Blue for 2012
Season The wet spring and summer of 2012 retarded the appearance of argus to the timing of the 1990s and made it difficult to get a good count at many sites. The Minsmere count on 26 June was premature, the back-up count on 5 July was rained off, and most of the minor colonies went uncounted this year. The lack of good flying weather must have inhibited breeding opportunities, and in all it was a disappointing season. Results of Annual Count Whilst the main sites were counted, mostly just off the population peak, many of the lesser sites again went uncounted. A total of only 16 out of 45 sites were counted, and the resulting total figure of 1270 looks distressingly low. But most colonies are in reasonable health, although there are five where there is cause for concern. At Walberswick NNR not a single SSB was found, despite repeated visits, and it would appear that this important colony has been lost. The heather encroachment at Minsmere Potbriggs was not completed last year, but will be tackled this winter. Weak Colonies The colonies about which concern has been expressed since 2005 are Purdis Heath, Blackheath, and Martlesham Heath. All –are the subject of ongoing conservation work, but it is too soon to express great conviction that the problems are over. The habitat improvement at Purdis Heath could result in discernible benefits in the next few years, and a single-species transect has been established to monitor progress. Martlesham Heath is a larger site with a larger population, whilst Black Heath (Wenhaston) is a smaller population and still fragile. The Minsmere Potbriggs site must also be a cause for concern. The 2008 count there found 60 butterflies, but noted encroachment by bracken. Since then, the bracken has overwhelmed the site and the population too; it is likely to take several years after the bracken treatment (eastern half weed wiped 2011 and 2012) before the butterfly population can recover. Possible Local Extinction at Walberswick NNR Counts at the Walberswick site, close to the New Delights Walks, declined gently from 40 in 2005 to 31 in 2009, but no Silver-studded Blues have been seen there since. This population collapse is worrying, particularly as –count visits were made this year, but they failed to find a single Silver-studded Blue at this National Nature Reserve. The bell heather still looks good, but it seems likely that the colony has been lost. Flooding of the lowest part of the site may have been a contributary factor, but this should not have spoiled the habitat higher up.
Dunwich Forest Compartment In the Dunwich Forest, the Westleton Heath population has re-colonised a former forest compartment, and this was reported as a positive development last year. Although no formal count was made this year, it was disappointing to note how vigorously the bracken had invaded the site.
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Blaxhall Common The transect walk at Blaxhall Common achieved another good year, finding a new highest count of 48 Silver-studded Blues. They were on the wing over a seven week period from 26 June to10 August. For the first time, an observer saw one to the south of the B1069. This marks ongoing geographic expansion during five successful seasons after the translocation, a benchmark for the successful establishment of the colony.
Tabulation The results of the 2012 counts are tabulated in the accompanying spreadsheet. Of the 16 sites surveyed, three were unoccupied, including Walberswick NNR where the colony appears to have been lost. The total count represents just 23% of the 2006 datum, the result of an incomplete survey in a below average year. Past tabulations have shown Upper Hollesley Common 3d and Dunwich Heath; both sites have occasionally recorded strays, but since neither of them are established colonies, they have now been delisted, leaving 45 sites to be monitored when possible. 2012 COUNTS – Monitored Silver-studded Blue Sites listed geographically from the North Location Blackheath Wenhaston Walberswick NNR Dunwich Forest Area 4 Westleton Heath NNR Westleton Common Westleton Football Pch. Minsmere Foraged Sq. Minsmere Reversion Fd. Minsmere Sawmills Minsmere Football fld. Minsmere Natterjack pit Minsmere SW Comp 1 Minsmere Pit Comp2 Minsmere SE Comp 3 Minsmere Comp 20 N Minsmere Comp 20 S Minsmere S Comp3 Minsmere Central C.3 Minsmere Powerlines Minsmere N. Bridleway Minsmere Potbriggs
Grid Ref. TM420749 TM451727 TM461702 TM4569 TM443687 TM444688 TM459689 TM451689 TM452692 TM451691 TM451693 TM450694 TM457692 TM457691 TM446683 TM445680 TM456693 TM453693 TM461683 TM468687 TM468689
Observer
♂
♀
Total
11-Jul Jul
R. Havard W. Russell
3 0
1 0
24-Jul 12-Jul 12-Jul
W. Russell D. Rous D. Rous
12 86 9
3 21 2
5-Jul
M. Kemp
207
69
4 0 0 15 107 11 0 276 0 0 0 0 0 0 0 0 0 0 0 0 0
Date
Continued over page
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2012 COUNTS –continued Location
Grid Ref.
Minsmere N. Grimstones TM462688 Minsmere E Comp 13 TM468681 Minsmere C.13 track TM464681 Minsmere C.13 Tanktrap TM466683 Minsmere Gravel Pit TM449669 Aldringham Walks TM464612 Blaxhall Common TM377566 Upper Hollesley MOD TM333472 SCDC TM335471 Lower Hollesley 'A' TM342465 Lower Hollesley 'B' TM343461 Lower Hollesley 'C' TM350458 LHC Barthorpes small TM349460 LHC compt 1e TM346462 Firebreak TM350456 LHC compt 8c TM338468 Rushmere Heath TM202448 Martlesham Heath TM2344 Parsnip Plantation TM327458 Ipswich Golf Club TM208432 Purdis Heath TM212427 Ransomes CWS TM207419 Ind. Est. Jacobsen TM200410 Ind. Est. lagoon fringe TM207415 Sites counted: 16 of 45 with 3 empty Datum good year: This year as
Trans. Suffolk Nat. Soc. 49 (2013)
♂
♀
Total
5-Jul M. Kemp
311
74
12-Jul D. Thurlow 27-Jul T.Peake 25-Jul N. Mason
20 38 46
3 10 21
4-Jul R. Stewart 4-Jul R. Stewart 13-Jul N. Mason
34 73 37
3 9 18
0
0
1 0 14 21
1 0 3 3
385 0 0 0 0 23 48 67 0 37 82 55 0 0 0 0 0 117 2 0 17 24 0 0
2012 Totals: 912
241 143 8
Date
23-Jul 13-Jul 16-Jul Jul Jul 5-Jul
Observer
D. Basham P. Smith A. Morgan N. Sherman J. Dowding J. Dowding
5-Jul J. Dowding
2006 Totals: 3617 % of 2006:
1270 5470 23%
BUTTERFLY REPORT 2012
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Annex D. Dingy Skipper Survey, 2012 Overview There have been a couple of interesting developments with Dingy Skipper in 2012, despite a cool wet spring which deferred the flight season and compressed survey opportunities into relatively few sunny days. The presence of a colony at the northern end of the NWT reserve on Thetford Heath was confirmed, with the butterfly again flying in the nearby forestry restock area, but not on RAF Barnham. The core of the King's forest colony seems healthy around the Archery area, and it was very encouraging to find it flying to the north along Chalk Lane and to the south in the Wordwell rides, where none have been seen for a few years. 2012 Survey This year's survey involved 16 recorders, although many of these attended the pre-arranged searches which turned out to be too early. Searches at Center Parcs and RAF Barnham again failed to find any Dingy Skippers. The first sighting on the county border at the Devil's Dyke was on 7 May, but none were seen in Suffolk until 18 May. The weather improved thereafter, and returning individual recorders found them flying in King's Forest from 22 May to 28 May. Although the highest one-day count was just twelve, the numbers seen in different areas suggest that more were present (Chalk lane 10, Archery area 9, Wordwell 8). The sightings at Thetford Heath and the Thetford Forest are pleasing, and a number of former sites were also checked, albeit with negative results. The sites visited are listed below, with more detail. RAF Barnham TL8580/8680 A thorough search was made in suitable weather on 24 May, but once again not a single Dingy Skipper was seen. Some bird’s-foot trefoil was present, and although some of the habitat looks suitable, most of the former flight area is shaded out. It seems that although the Dingy Skipper is breeding on the adjacent Thetford Heath, it has gone from the Barnham SSSI. Last seen here in 2005. Thetford Rifle Range (MoD) TL8481 A visit here in good weather on 25 May confirmed the apparent suitability of the sward on the around the firing ranges. To date, no Dingy Skippers have ever been seen here. Thetford Forest/Thetford Heath TL8480 For the first time this year, we were able to visit the Thetford Heath nature reserve (staying clear of the stone curlew breeding area) and confirmed the 2011 observation by the NWT warden. In good weather on 24 May we found three Dingy Skippers roosting not far from the pit in the north west of the heath, but not in the pit itself, although this looked like perfect habitat. The presence of a mating pair was particularly encouraging. A minimum of three more were found in the re-stock area just north of the St Edmunds Way.
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Center Parcs, Elveden TL810805 This isolated colony existed on a small site that has been losing its suitable habitat to a build up of coarse grass. The cutting & rotovation work has not really created significant patches of bird’s-foot trefoil. Center Parcs staff visited the area regularly in May, without seeing any Dingy Skippers. Last seen here in 2006. In King's Forest (overall): First found on 22 May (later than usual). Best count: twelve on 26 May. Latest sighting: 28 May. Extent: From Wordwell to Chalk Lane, but confined to two tetrads, without any to the west of the B1106 this year.
King’s – Chalk Lane area (TL8275 and TL8374) Seven were seen in the Chalk Lane area on 28th May. King’s – Archery Restricted area TL833737 The best count here was just nine Dingy Skippers on 22nd May, by which time the weather had improved, but no mating pairs were seen this year. The secluded open area between the mature beech to north and plantation to south which seems to be the main breeding site (TL834739) was only inspected once in fair weather though. King’s – Griffin’s Covert (East of Archery area, TL837732) A few sightings were made east of the Archery area this year, but further north than Griffin's Covert. King’s – Wordwell area TL834733 By 28 May, eight Dingy Skippers were flying in the Wordwell ride and along the e–w access track. It is encouraging that they have discovered the recently -widened areas. King’s – West of B1106 This area was again given a cursory check in 2012, but none were seen. Annex E. White-letter Hairstreak – 2012 Following two strong seasons, 2012 was rather flat. Although the five year rolling total remains strong at 76 tetrads, White-letter Hairstreak was seen in just 17 this year (3% of the county). It suffered from the wet summer, but so did the recorders, who had less opportunity to check its regular colonies. As a canopy butterfly, it is sometimes found by chance when it comes down to eye level on a fine day, but there were few fine days this summer. The future of the White-letter Hairstreak in Britain is still viewed with concern because of the long-term consequences of Dutch Elm Disease. Yet it remains an under-recorded species that can be found in most places where elm survives – provided sufficient effort is put into a search. In Suffolk, it frequently turns up on elm in established hedgerows, where they are free to move along when Dutch Elm Disease moves in.
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Annex F. White Admiral 2012 White Admiral, like Silver-washed Fritillary was one of the positive performances of 2012. It was seen in 47 tetrads (8∙2% of the surveyed area), with records from several woods not previously known for colonies. Partly, this was due to our searches of promising under-recorded woodland in pursuit of Silver-washed Fritillary, and both species seem to favour similar habitats – large damp woods with clearings or broad rides (obviously with violets and honeysuckle as larval host-plants and supplemented by bramble or thistle as nectar sources). This year it was found in greater numbers too, with counts at Bradfield Woods as high as 19 on one day, and a season total of 84 on transect, and this in a wood that did not have a regular colony nine years ago. Its five-year total of 93 tetrads is the highest-ever (8∙5% of the county) is a pleasing result for a BAP species. Annex G. Grayling 2012
Grayling 2012 showing East-West split (47 tetrads). The only transect with Grayling in the west of the county is Cavenham Heath, and the annual count there hit an all time low in 2010, but has recovered slightly in 2011 and 2012, but still remains well below its 2002/3 highs. Added to the UK BAP Priority species list in 2007, the Grayling has lost 45% of its UK distribution over the past 30 years, and is now essentially a coastal species. Losses have been no less dramatic in Suffolk, and it is now very
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localised in its favourite Breckland haunts and extremely rare in Mid Suffolk, although it remains widespread in the Sandlings. Overall, its distribution has remained stable since 2000, being found in 9% of the county. This year, several recorders found unusually high counts on some Sandlings sites, although a comparison between east and west reveals that both tetrad counts and numbers seen have been dropping off in the west of the county for the past three years, whereas results from the east have improved slightly to provide the counterbalance. Annex H Wall Brown Survey: 2011/2012 SNS/BC Single-species Survey. The organized survey started by selecting 15 paired tetrads, one which had Wall records in the previous two years, paired with an adjacent tetrad with records from four or five years back, but none since. The idea was to get surveyors to find them flying in the primary good site, and then (ideally on the same day) to search the secondary tetrad in the hope of finding that they were still resident there too. 15 volunteers enrolled to provide cover of those squares, and some late additions extended the original plan with four extra unpaired tetrads. A total of 55 people contributed records, from their own gardens, in a couple of cases. 2011 Results The bad news is that, for the second year in succession, not a single Wall was recorded from West Suffolk (TL tetrads). Five paired tetrads were thoroughly searched. Results for TM were also disappointing, with most sightings being close to the coast, and, in known strong colonies. At least, the survey improved our understanding of where the best remaining coastal habitat is still occupied. It appears that the Wall is only hanging on close to the sea or river estuaries, usually where unkempt grasses grow unmown on embankments and sea walls. The most westerly record was from Thorpe Bay on the Orwell estuary (TM2537), and the furthest inland was Bredfield (TM2753). The northern areas of Lowestoft & Gorleston (TG) were not target tetrads, but the Wall is holding on there relatively well. In all, Wall was recorded from 30 tetrads in 2011, as against 27 in 2010 – so the considerable extra recording effort produced mostly negative results, without the surge of sightings that might have been expected. 34 target tetrads were selected, and 30 of these were visited at least once, but four went unvisited. Only two primary "promising/strong" squares had Wall sightings. (but in neither case were they found both in 1st and 2nd generations). None of the secondary squares had any Wall sightings (all of these had Wall five or six years previously). Four extra unpaired squares were surveyed by volunteers joining after the main allocation, but none were seen in these squares either. The majority of sightings came in from roving recorders, plus a few from the Wider Countryside Butterfly Survey and the Big Butterfly Count. A total of 66 Wall records were noted, many from Shingle Street, Bawdsey & Boyton areas. A total of 30 tetrads had Wall records. Most sightings were of singles;
Trans. Suffolk Nat. Soc. 49 (2013)
BUTTERFLY REPORT 2012
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the highest number seen together was six. This in itself reflects a declining population. The map below shows how coastal the distribution has become.
2011 Wall in 30 tetrads – (4∙4% of 677) – but none in TL (West Suffolk).
2012 Wall in 23 tetrads – mostly coastal & river estuaries.
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2011 Wall in 30 tetrads – (4∙4% of 677) – but none in TL (West Suffolk).
2012 Results Monitoring the Wall remained a priority, so recorders extended for 2012. The survey continued, but using different ground rules. The 2011 targets were clearly optimistic. So no targets were set in TL for 2012. Nonetheless, there was some encouraging news from TL, as there was an unconfirmed sighting of two Walls close to Sedge Fen. Infill targets were set for coastal tetrads in TM and TG, and continued monitoring of last year's TM targets was undertaken. However, the results have been generally disappointing, with almost all sightings coming from the known hot spots from Shingle Street to Boyton and Bawdsey. Wall was seen in a total of just 23 tetrads in 2012. The survey sadly confirmed that the Wall is moving east even faster than we already knew. Coastal Work The Environment Agency has an ongoing programme of coastal defence work, and this is planned to reach the Bawdsey/Shingle Street seawall in 2013, potentially disturbing our best Wall habitat. In addition, the Environmental Information Summary for the proposed East Anglia ONE offshore wind farm reveals that its undersea cables are likely to come ashore at Bawdsey - crossing one of our strongest Wall colonies. In both cases, appropriate mitigation measures are under discussion. The Decline of the Wall over Successive Surveys
Table extracted from Annex B The Decline of the Wall over successive five year periods From
1995 2000
2001
2002
2003
2004
2005 2006 2007
2008
to
1999 2004
2005
2006
2007
2008
2009 2010 2011
2012 5 yrs
Period 5 yrs
5 yrs
5 yrs
5 yrs
5 yrs
5 yrs
5 yrs 5 yrs 5 yrs
Wall
200
183
163
160
136
120
2009 2010 2011
350
115
100
96
And for successive single year periods to 2012 1 Year 2003 2004
2005
2006
2007
2008
2012
Period
1yr
1yr
1yr
1yr
1yr
1yr
1yr
1yr
1yr
1yr
Wall
83
66
39
44
27
28
36
27
31
23
Trans. Suffolk Nat. Soc. 49 (2013)
