Page 1

RUNNING HEAD

47

2008 BUTTERFLY REPORT ROB PARKER From the start, 2008 was destined to be a poor butterfly season. The previous wet year left low numbers of insects passing the winter of 2007/2008 as eggs, larvae, pupae or adults. Although much of that winter was relatively mild, the frosts of 23/24/25 March further reduced the number of survivors. Most species had a poor year, and a shortage of migrants suppressed variety as well as total numbers. Many observers commented that it was the worst season they could remember. Nationally, Butterfly Conservation declared 2008 the worst butterfly year for 25 years. Fortunately, there were a few bright spots to offset this gloomy assessment. Weather The winter months were mild judged by average temperatures, but spoiled by snow in March. Thereafter, mean temperatures for East Anglia were slightly above historic averages, subsiding to average by autumn (See table below). Spring was wet, and summer continued wet, with sun and temperatures close to normal. The rain and cloud reduced the number of days suitable for flying and mating, and butterfly activity was generally low. Table 1. 2008 Weather for East Anglia

Season

Winter 07/08 Spring Summer Autumn

Mean Temp Anomaly Sunshine Anomaly Rainfall

Anomaly

°C

°C

hrs

%

mm

%

5Â7 9Â3 16Â4 10Â1

2Â0 1Â1 0Â8 0

234 492 558 320

139 111 98 108

135 195 191 383

94 141 124 109

Source: www.metoffice.gov.uk/climate/uk Anomalies are measured against the 1961 to 1990 averages. A review of the number of days in spring when the sun shone in conjunction with temperatures of above 15°C (at the SNS weather station in Boxford) reveals that the maximum temperature remained below 15°C for the whole of March, and that only five days in April achieved that temperature without some rain. Unsurprisingly, transect walkers had great difficulty in getting any walks in within the stipulated weather criteria. May was slightly better, but there were still twelve days that failed to meet the basic butterfly flight criteria, delaying the emergence of species that had passed the winter as pupae. In June there were 13 days that provided little opportunity for flight, or pairing.

Trans. Suffolk Nat. Soc. 45 (2009)


48

Suffolk Natural History, Vol. 45

Monitoring the BAP Species There are now five Suffolk BAP priority species, and two in a new category of “for study only”. For the third year in succession, the Dingy Skipper was not found at RAF Barnham, and the colony may have been lost, although the habitat still looks adequate. There were no sightings from the isolated site at Center Parcs either. Although the King’s Forest survey turned up decent numbers, the overall picture gives serious cause for concern. The annual Silver-studded Blue count was more complete than 2007, but numbers were well below 2006 levels. The result of the translocation to Blaxhall Common was one of the high points of the season, and the newlyestablished transect recorded over a dozen butterflies flying close to last year’s release points during each week of the expected flight period. This first-year success is encouraging, but it is too early to assume that the new colony will survive, and the monitoring will be continued for five years at least. Meanwhile, the colonies at Martlesham Heath, Wenhaston Black Heath and Purdis Heath are all insecure, as the benefits of habitat improvement work have not yet kicked in. An independent ecological survey of selected colonies will be undertaken during 2009. The White-letter Hairstreak was the subject of a nationwide survey organized by the Herts & Middx Branch of Butterfly Conservation. This was remarkably successful, finding elm and White-letter Hairstreaks within 10 km of most of the targeted survey squares. In Suffolk we confirmed White-letter Hairstreak within 2 km of the target squares, and added no less than 10 new tetrads to our knowledge of the butterfly’s distribution. Clearly, this result confirms that the butterfly is more widespread than historic records suggest (although it is still discovered only by diligent searching). Since 1995, the White-letter Hairstreak has been found in almost 8% of the county’s 1089 tetrads, a result that reflects recording effort as well as any spread of the species. White Admiral is apparently expanding in Suffolk woodlands, partly as a result of intense recording activity. It has been noted in 56 tetrads (5%) in the past three years, compared with 13 (1%) in the 1983–1985 survey. The situation here is more favourable than in the UK as a whole. Grayling is in decline in Suffolk in a similar pattern to the UK-wide situation. In recent years, it has been lost from many inland locations and its present distribution is restricted to well-drained sandy soils of low fertility, where sparse grassland is found, mainly in the Brecks and the Sandlings. Separate detailed accounts for each of the above five BAP species follow as annexes. The 2007 revision of the UK BAP species lists two further species for enhanced monitoring. In both cases, the larval host plant is grass: The Wall is in decline in the UK and in Suffolk. In recent years, it has been lost from many inland locations and its present distribution is restricted to well-drained sandy soils of low fertility, where sparse grassland is found, mainly in the Sandlings and the NW corner of the county. Small Heath is in a less critical situation than the Wall, but appears to be losing ground on farmland amongst fertilized grass. It has been recorded from 168 tetrads in the past three years (15%), but numerical counts are falling at the few transect sites which still support it.

Trans. Suffolk Nat. Soc. 45 (2009)


RUNNING HEAD 2008 BUTTERFLY REPORT

49

Residents – Winners & Losers Most of our resident species had another poor showing. Notably, the Common Blue & Brown Argus were found in fewer squares than usual and their transect indices were well down. Compared with last year, only 64 Common Blues were counted on transects compared to last year’s 161. For the Brown Argus, the corresponding figures were 53 compared to 286 – a dramatic oneyear fall. Small/Essex Skippers were down to 40% of their 2003 levels judged by transect results, although the tetrad count was comparable to last year’s. Furthermore, flight periods seemed shorter than usual, which does not bode well for next season. Small Tortoiseshell and Peacock were both patchy, probably due to the presence of the recently arrived parasitic Tachinid Sturmia bella. Unexpectedly, an inward migration of Small Tortoiseshell boosted the numbers at the start of September. Several recorders noted that 2008 was “the year of the Whites”, although this perception was probably enhanced by the absence of anything else! Closer scrutiny of the overall figures suggests that the Green-veined White was actually less well represented than in recent years. The Red Admiral was not much in evidence in early spring as a result of the frosts, and the numbers at autumn ivy were also unimpressive, though it was still on the wing through October, along with Large Whites and Small Coppers. Purple Emperor The introduced Purple Emperors in Theberton Woods were still flying, although the shortage of sunshine provided few good viewing days. Migrants & Vagrants An early Large Tortoiseshell at Ipswich Golf Club was an unexplained vagrant, as was a second in September. Two Camberwell Beauty sightings were reported as well as two Swallowtails. Like 2007, the year was notably short of migrants, both butterflies and moths. A smattering of Painted Lady arrived, but Clouded Yellow was only reported four times all year. Early/Late Records Spring was neither early nor warm, and only two unusually early summer emergences were noted. A Meadow Brown on 5 May and a Small Skipper on 17 May were isolated and freakish occurrences, both being three weeks ahead of the established earliest ever records. Summer rain seemed to hold back emergences in some instances, with numbers rising quickly with the arrival of a couple of fine days, only to fall off again rather quickly. It seemed that the flight period was shorter than usual for most species. Autumn was unexceptional; some Large Whites and Red Admirals flew in November, but no later than ever records arose. Geographic Coverage Over 180 observers contributed records this year, covering 549 tetrads. 2008 brings cover of the county to 80% (865 tetrads) in the second five-year block since the end of the Millennium survey. In other words, there are still 223 tetrads still to be surveyed in 2009. Maps showing “black holes” were made available on the website to help recorders to visit as many as possible.

Trans. Suffolk Nat. Soc. 45 (2009)


50

Suffolk Natural History, Vol. 45

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 total species count stands at 35, including the introduced Purple Emperor. The average number of species recorded per tetrad was 9Â0, marginally below the 2007 figure of 9Â1 (adjusted by late records). Analysis The 35 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. Our most widespread residents were Meadow Brown, Large White and Speckled Wood, with Red Admiral falling back from the lead to eighth this year. Other “common species” to lose ground materially included the Green Hairstreak and Brown Argus. Lesser declines were noted for Small Copper and Brimstone. The Common Blue had another below average year. 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 (note though, that 2006, 2007 and 2008 have all been poor compared to 2005). Trends over a longer period are presented separately at Annex B for our 31 regular species. The decline of the Dingy Skipper will not be reflected in the five-year analysis until 2009. Other species that have achieved wider distribution in the past five years than in the Millennium Survey continue to hold their positions. In particular, the Speckled Wood continues its progressive expansion. White Admiral and White-letter Hairstreak are again shown as if expanding, although this is largely due to the determined recording effort that has pursued them. Transects The “index” derived from transect walks gives a valid evaluation of a species’ abundance, whereas distribution maps fail to detect dilution until populations are seriously depleted. The 16 full transects walked this year did reflect falling numbers of Common Blue and Brown Argus, with a longer-term decline of several other species including Grayling and Small Heath. 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 (Will Russell), Spring Lane (Rob Parker), Combs Wood (Liz Cutting), Ramsey/ Hintlesham and Wolves Wood (Mark Nowers), Newsons Farm (Frances Bee), Upper Abbey Farm (Trudy Seagon), Alton Water (Simon Waters), Manor Farm (Brenda Hudson) and Tythe Farm (Peter Vincent). 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. Results from BMS transects nationwide show that twelve species recorded their worst-ever indexes in 2008. Eight of these species occur in Suffolk: Small/Essex Skipper, Large Skipper, Dingy Skipper, Orange-tip, Green Hairstreak, White-letter Hairstreak, Small Tortoiseshell and Small Heath. In most cases, the same species also performed poorly in Suffolk.

Trans. Suffolk Nat. Soc. 45 (2009)


RUNNING HEAD 2008 BUTTERFLY REPORT

51

Annex A. Scarcity for 35 species seen in Suffolk in 2008 Tetrads per Species - 2007 & 2008 (Species listed in order of scarcity in 2008) % of 509 Tetrads tetrads 2007 Species 0Â4 0Â2 0Â2 0Â4 0Â6 2Â0 5Â7 2Â9 4Â5 5Â3 4Â5 5Â9 9Â6 6Â3 17Â7 35Â4 17Â1 16Â3 21Â6 25Â1 24Â4 31Â2 34Â2 37Â3 40Â3 38Â7 33Â6 46Â4 66Â4 47Â7 59Â5 48Â7 56Â6 57Â2 54Â2 57Â8

Tetrads % of 549 2008 tetrads *cf last Remarks

2 Marbled White nil 1 Purple Emperor 1 1 Swallowtail 2 2 Dingy Skipper 2 3 Large Tortoiseshell 2 10 Camberwell Beauty 2 29 Clouded Yellow 5 15 Silver-studded Blue 15 23 White-letter Hairstrk 24 27 Wall 28 23 White Admiral 32 30 Purple Hairstreak 33 49 Green Hairstreak 35 32 Grayling 37 90 Brown Argus 38 180 Painted Lady 68 87 Small Heath 84 83 Essex Skipper 99 110 Small Skipper 125 128 Common Blue 128 124 Large Skipper 131 159 Small Copper 145 174 Brimstone 157 190 Holly Blue 197 205 Orange-tip 236 197 Small Tortoiseshell 241 171 Ringlet 246 236 Gatekeeper 281 338 Red Admiral 289 243 Comma 300 303 Small White 305 248 Green-veined Wht 307 288 Peacock 307 291 Speckled Wood 317 276 Large White 343 294 Meadow Brown 361

0Â2 0Â4 0Â4 0Â4 0Â4 0Â9 2Â7 4Â4 5Â1 5Â8 6Â0 6Â4 6Â7 6Â9 12Â4 15Â3 18Â0 22Â8 23Â3 23Â9 26Â4 28Â6 35Â9 43Â0 43Â9 44Â8 51Â2 52Â6 54Â6 55Â6 55Â9 55Â9 57Â7 62Â5 65Â8

0Â93 1Â85 0Â93 0Â62 0Â19 0Â16 0Â93 0Â97 0Â96 1Â29 1Â02 0Â66 1Â07 0Â39 0Â35 0Â90 1Â11 1Â05 0Â93 0Â98 0Â85 0Â84 0Â96 1Â07 1Â13 1Â33 1Â10 0Â79 1Â14 0Â93 1Â15 0Â99 1Â01 1Â15 1Â14

Intro’d at Theberton BAP sps in trouble

poor migration year stable BAP species BAP species new BAP species

new BAP species significant decline poor migration year

another weak year weak weak

a better year

falls back 6 places falls back 4 places

gains 4 places commonest

35 species seen in Suffolk in 2008 (including introduced Purple Emperor) *cf “last” indicates the proportion of last years cover achieved in current year.

Trans. Suffolk Nat. Soc. 45 (2009)


52

Suffolk Natural History, Vol. 45

Annex B. ANALYSIS – 2000 to 2008 A measure of Abundance – for residents and regular visitors

Survey from: to:

2000 2004

2002 2006

2003 2007

2004 2008

5yrs 5yrs 5yrs 878 865 868 11Â9 11Â8 12Â1 Tetrads from which recorded Small Skipper 261 290 322 Essex Skipper 240 253 267 Large Skipper 228 259 295 Dingy Skipper 7 7 8 Clouded Yellow 192 87 111 Brimstone 249 290 317 Large White 579 617 599 Small White 576 622 606 Green-veined White 520 572 552 Orange Tip 401 455 439 Green Hairstreak 83 85 88 Purple Hairstreak 109 112 120 White-letter Hairstreak 43 54 70 Small Copper 297 310 341 Silver-studded Blue 20 20 20 Brown Argus 160 169 193 Common Blue 327 367 383 Holly Blue 370 476 419 White Admiral 36 46 61 Red Admiral 538 571 577 Painted Lady 410 396 448 Small Tortoiseshell 538 615 621 Peacock 468 527 532 Comma 403 457 475 Speckled Wood 535 572 565 Wall 200 183 163 Grayling 107 107 107 Gatekeeper 495 524 504 Meadow Brown 582 615 591 Ringlet 334 378 397 Small Heath 195 205 209

5yrs 879 12Â6

5yrs 918 12Â7

349 281 325 8 119 368 637 657 594 480 103 123 75 371 21 230 402 454 65 640 472 655 585 526 608 160 100 558 648 438 229

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

Period: Tetrads:Species/Tetrad:

Notes: Rare migrants excluded Late records for 2006 incorporated

Trans. Suffolk Nat. Soc. 45 (2009)

2001 2005


RUNNING HEAD 2008 BUTTERFLY REPORT

53

Annex B. ANALYSIS – continued

Survey from: to:

2004

2005 2006 2007 2008

Period: Tetrads:Species/Tetrad:

1yr 536 8Â5

1yr 500 10

1yr 557 9Â4

1yr 509 9Â1

1yr 549 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

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

158 100 161 4 55 176 305 296 212 221 36 44 35 163 15 86 203 179 39 369 271 269 282 281 288 44 52 261 335 210 95

110 83 124 2 29 174 276 303 248 205 49 30 23 159 15 90 128 190 23 338 180 197 288 243 291 27 32 236 294 171 87

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

Trend

Serious concern

Well recorded Stable

Expanding

Expanding Declining Declining

Declining

Trans. Suffolk Nat. Soc. 45 (2009)


54

Suffolk Natural History, Vol. 45

Annex C. Annual Report on Silver-studded Blue for 2008 Season 2008 began slowly, with some frosts and snow and sleet storms in April, followed by cool days with heavy cloud and very few days above 15°C. The first males were flying by 15 June (later than 2007 by eleven days). Peak counts at most sites were achieved during the last days of June and the first week of July. Positive Developments Recent extensions of range have been maintained and there has been encouraging consolidation in Minsmere’s reversion field, which recorded an impressive count of 526. Recent gains at Upper Hollesley, Lower Hollesley and Parsnip Plantation have been maintained. Two newly-found colonies (Lower Hollesley Compartment 1e and Industrial Estate/Jacobsen) have been added to this year’s table. Blaxhall Common Translocation The newly established transect walk at Blaxhall Common worked nicely, and found about a dozen Silver-studded Blues on the wing over a four week period from 4–26 July. Both sexes were found, and their flight areas were in the vicinity of the release points, and also over an area of mature heather some 100 m NW of the closest release point. A full report on the translocation has been published as a special edition of the Suffolk Argus. Although this first season success is just a start, it is nonetheless a very satisfactory beginning. The fresh colony will be closely monitored for at least five years. Weak Colonies The three colonies about which concern was expressed in 2005 to 2007 are all still extant, with management work improving the habitat. At Wenhaston (Blackheath) the recently foraged area was again in use. At Purdis Heath, the foraging has extended the pioneer heather area, though the count was no stronger than last year. Work at Martlesham Heath has opened a corridor through gorse, but the scale of the management task remains a challenge for the Conservation Group. All of these weak colonies will be professionally surveyed during 2009. Survey Results The 2008 counts were more complete than 2007 (which had been disrupted by poor weather) and an excellent total of 46 sites were visited out of 47 – more than last year, thanks to the establishment of three extra colonies. The resulting total figure of 4052 compares reasonably (at 74%) with 2006’s high count of 5470. At three individual sites, the 2006 count was exceeded this year, although at the insecure colony at Wenhaston, the figure was just 33%, and the Walberswick NNR counts have halved over the past four years. Despite last year’s poor showing, most of the colonies are in decent health. The mini transects at Minsmere reached a peak on 30 June, five days after the main count. The distribution map for the 2008 counts shows records from 15 tetrads, and is reproduced below. Such a map shows presence, but does not reveal the condition of each site or its butterfly colony. In general, the larger, wellmanaged coastal sites are doing well, whilst the isolated inland sites are those where the colony has a weaker tenure.

Trans. Suffolk Nat. Soc. 45 (2009)


RUNNING HEAD 2008 BUTTERFLY REPORT

55

2008 Count Map: 15 tetrads (minor change at Walberswick, otherwise as 2007).

YEAR on YEAR Totals for main sites Location Blackheath Wenhaston Walberswick NNR Aldringham Walks Westleton Heath NNR Westleton Common Minsmere Sawmills Minsmere Potbriggs Minsmere North Grimstones Blaxhall Common Upper Hollesley MOD Lower Hollesley 'A' Lower Hollesley 'B' Lower Hollesley 'C' Martlesham Heath Purdis Heath Industrial Estate Total

Grid Ref.

2005 2006 2007 2008

TM420749 TM451727 TM464612 TM4569 TM44306870 TM452692 TM468689 TM462688

1 36 217 176 252

24 37 154 164 365 ~ 1094 47 148 405 757

TM33344723 TM342465 TM343461 TM352458 TM2344 & 2444 TM21204270 TM207419

192 76 467 271 335 234 24 55 377 280 6 25 67 127 2602 3811

13 32 32 130 131 231 47 338 60 51 131 63 26 159 15 71 1530

8 22 67 75 335 563 60 600 15 176 176 283 66 126 16 66 2654

Trans. Suffolk Nat. Soc. 45 (2009)


Suffolk Natural History, Vol. 45

56

Monitoring The results of the 2008 counts are summarised below. Of the 47 listed locations, 46 were successfully surveyed, although 13 were unoccupied. A year-on-year comparison for the main sites reflects a better year than 2007, but still rather weak, averaging 70% of the 2006 count: 2008 COUNTS –Monitored Silver-studded Blue Sites listed geographically from the North (46 sites counted out of 47 with 13 empty) Location Blackheath Wenhaston Walberswick Comn NNR Walbers NNR, Newdelight 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 Minsmere Gravel Pit Blaxhall Common UHC 3d Upper Hollesley MOD SCDC Lower Hollesley 'A' Lower Hollesley 'B'

Grid Ref. TM420749 TM491752 TM451727 TM464612 TM4569 TM44306870 TM44406880 TM459689 TM451689 TM452692 TM451691 TM451693 TM450694 TM457692 TM457691 TM446683 TM445680 TM456693 TM453693 TM461683 TM468687 TM468689 TM462688 TM468681 TM464681 TM466683 TM468687 TM449669 TM377566 TM337480 TM33344723 TM3357447121 TM342465 TM343461

Trans. Suffolk Nat. Soc. 45 (2009)

Date

Observer

29.07 Richard Havard Not counted 08.07 Adam Burrows 01.07 Rob Macklin 08.07 Adam Burrows 01.07 David Rous 01.07 David Rous 01.07 Mel Kemp 01.07 Mel Kemp 25.06 Mel Kemp 25.06 Mel Kemp 01.07 Mel Kemp 01.07 Mel Kemp 01.07 Mel Kemp 01.07 Mel Kemp 01.07 Mel Kemp 01.07 Mel Kemp 01.07 Mel Kemp 01.07 Mel Kemp 01.07 Mel Kemp 01.07 Mel Kemp 25.06 Mel Kemp 25.06 Mel Kemp 01.07 Mel Kemp 01.07 Mel Kemp 01.07 Mel Kemp .07 01.07 Mel Kemp 01.07 David Mason 04.07 David Mason 04.07 David Mason 04.07 David Mason 01.07 Richard Stewart 01.07 Richard Stewart

ƃ

Ƃ Total 5

3

18 58 67 294 11 4 445 492 137 54 10 199 32 60 0 0 0 0 0 52 528 0 0 0 0 32 13 0 151 2 155 243

4 9 8 41 0 3 81 71 29 19 3 91 10 9 0 0 0 0 0 8 72 0 0 0 0 10 2 0 25 2 21 40

8 0 22 67 75 335 11 7 526 563 166 73 13 290 42 69 0 0 0 0 0 60 600 0 0 0 0 42 15 0 176 4 176 283


RUNNING HEAD 2008 BUTTERFLY REPORT

57

2008 COUNTS – continued Location Lower Hollesley 'C' LHC Barthorpes small LHC compt 1e Firebreak LHC compt 8c Rushmere Heath Martlesham Heath Parsnip Plantation Ipswich Golf Club, Purdis Purdis Heath Industrial Estate Ind. Est. Jacobsen Ind. Est. lagoon fringe

Grid Ref.

Date

TM352458 TM3495346020 TM34644620 TM350456 TM3382846820 TM202448 TM2344 & 2444 TM32724579 TM207415 TM21204270 TM207419 TM2041 TM207415

30.06 30.06 30.06 30.06 30.06 08.07 13.07 04.07 .07 04.07 24.06 24.06 24.06

ƃ

Observer

Ƃ Total

David Mason 56 10 66 David Mason 35 1 36 David Mason 10 6 16 David Mason 6 1 7 David Mason 11 4 15 David Mason 0 0 0 Phil Smith 84 42 126 David Mason 58 15 73 Neil Sherman 0 0 0 Neil Sherman 12 4 16 Julian Dowding 49 17 66 Julian Dowding 6 2 8 Julian Dowding 0 0 0 2008 Totals: 3389 663 4052

Some of the results are shown graphically below. The slight recovery at Aldringham Walks is reassuring.

Annual SSB Counts 350 300 250 Aldringhm

200

Walbers

150

Blackhth

100 50 0 1

2

3

4

5

Trans. Suffolk Nat. Soc. 45 (2009)


58

Suffolk Natural History, Vol. 45

Annex D. Dingy Skipper Survey, 2008 Summary The survey involved 19 people, and 34 man-days, but searches at Center Parcs and RAF Barnham failed to find any Dingy Skippers. To guard against an early start to the season, checks were begun at the King’s Forest in fine weather on 26/4. First flights were noted on the county border along the Devil’s Dyke on 5/5, and in the King’s Forest on 13/05 (a week’s delay is normal). The flight season apparently reached a peak in the week 18 to 24 May. Cool wet weather thereafter made for few sightings. The latest was on 31/5. Another year without any sightings at RAF Barnham or Center Parcs is of grave concern. The Dingy Skipper is losing ground and if the colonies at these two sites have been extinguished, the King’s Forest is now the only remaining Suffolk population. Even there, the original Wordwell ride produced only a single sighting this year, although the butterfly was found to be spreading out from the Archery area to other apparently suitable rides. Possibly these were stray singletons though; there was no evidence of breeding away from the Archery area. The sites visited are listed below, with more detail. This year’s effort was concentrated on the most promising sites, including the peripheral areas of the King’s Forest. RAF BarnhamTL 8580/8680 – An extensive search in good weather on 7 May found the bird’s-foot trefoil was present, but under-developed, and no Dingy Skippers were seen. Another visit was made in cooler weather on 19 May (immediately after the first sighting in King’s Forest) but none were found. A third visit had to be cancelled, and whilst the warden’s routine inspections failed to see any, the 2008 searches were by no means conclusive proof that the colony has been totally extirpated. Center Parcs, Elveden TL810805 –This isolated colony exists on a small site that is progressively losing its suitable habitat to a build up of coarse grass. Four pairs of eyes, including BC’s Eastern Region Conservation Officer, conducted a search in bright intervals on 21 May, but without finding a single Dingy Skipper. Center Parcs staff made further visits in better weather, but still saw none. Discussing the possibilities for managing the site, it was concluded that there was nothing to be lost by creating a long curve of bare soil in the prime area near the drainage ditch. This would set the grass back and disturb the seed bank, triggering re-growth of bird’s-foot trefoil. A sideby-side mown/rotovated strip is proposed, taking care to preserve the milk parsley growth favoured by the bumblebees. In King's Forest: First found 13/5 (after a good negative check on 7/5) Best counts: 21 on 18 May, also 21 on 24 May, in different places. Latest sighting 31/5

Trans. Suffolk Nat. Soc. 45 (2009)


RUNNING HEAD 2008 BUTTERFLY REPORT

59

King’s - Chalk Lane area (TL 8275 & 8374) TL827752 - 18/5 (1), 24/5 (1), 31/5 (1) TL826754 (1) & 829753 (1) & TL833749 (1 in the heathland reversion square, further east) all on 24/5 King’s - Wordwell area TL834733 13/5 First sighting of 2008, and the only one at Wordwell Negative searches in good conditions on: 18/5, 21/5, 24/5 (by 2 separate parties), 28/5, 31/5. Looking grim, really. The habitat is deteriorating somewhat along main ride, but decent bird’s-foot trefoil growth along east-west access track (full length checked). In December 2008, the Forestry Commission undertook special felling to widen the ride by felling 30 m of pine from the eastern side. This will let more sunlight in and should improve the habitat quality. King’s - Archery Restricted area TL833737 The secluded open area between the mature beech to north and plantation to south seems to be the best-used habitat (TL834739), but the northern margin of the east-west ride south of the Archery hut is productive too, as is the northsouth conservation ride bounding the archery restricted block. Sightings have also been made on the eastwards extension of the east-west ride to TL836735. The highest one-day count in this area was 20 on 18/5. Mating pairs have been found on 3 occasions (18/5 (1) & 24/5 (2)). King’s - East of Restricted area This year, encouragingly, 2 sightings have been made further east than ever before (well, back to 1995, anyway). One was at TL837737 on 24/5, and the other was on 23/5, at TL839732 where there is some Lotus. The ride extends east into the next tetrad, although none were seen flying in the apparently suitable habitat there. Annex E. White-letter Hairstreak – 2008 The future of the White-letter Hairstreak in Britain is viewed with some concern largely because of the uncertain consequences of Dutch Elm Disease. Yet it remains an under-recorded species that can be found in most places where elm survives whenever intensive effort is put into a search. A nationwide survey during 2008/2009 rather proved this point by finding the butterfly (or its early stages) within a few kilometres of most of the randomly selected squares. In Suffolk we confirmed White-letter Hairstreak within 2 km of the target squares, and added no less than ten new tetrads to our knowledge of the butterfly’s distribution. Clearly, this result confirms that the butterfly is more widespread than historic records suggest (although it is still discovered only by diligent searching). Since 1995, the White-letter Hairstreak has now been found in almost 11% of the county’s 1089 tetrads, a result that reflects recording effort as well as any spread of the species. Elm is still widely spread across the county, particularly in hedgerows, where the butterfly can survive

Trans. Suffolk Nat. Soc. 45 (2009)


60

Suffolk Natural History, Vol. 45

the ravages of Dutch Elm Disease by moving on to suckers not yet affected by the disease. In 2008, the White-letter Hairstreak was recorded from 24 tetrads (4Â6% of the 547 squares surveyed). It is clear that the butterfly is being found at many small sites spread across the county, many of them no more than a stretch of roadside elm hedge. Many of these represent transient populations as distinct to well-established colonies. Annex F. White Admiral 2008 White Admiral is apparently expanding in Suffolk woodlands. It has been noted in 67 tetrads (6Â1% of the county) in the past four years, compared with 13 (1%) in the 1983–1985 survey. The situation here is more favourable than in the UK as a whole, where its decline resulted in its being added to the UK BAP priority list in 2007. It inhabits damp woods with plenty of honeysuckle, and seems to have settled recently in several smaller woods that are not longstanding colonies. It is known that unofficial releases have been conducted in Dunwich and Tunstall Forests over a period of years (and probably in Theberton Woods too). Over the same period, climate change appears to have had a beneficial effect, and second generation emergences have been noted in good years (but not 2008). Progressive recording efforts have resulted in an increase in the tetrad count, but not all of the sightings indicate permanent colonization. Nonetheless, the past four years have produced good numbers, and it is encouraging to have a UK BAP species dong so well in Suffolk. In 2008, White Admiral was recorded from 32 tetrads (5Â8% of the 547 covered). Annex G. Grayling 2008 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 localised in its favourite Breckland haunts and extremely rare in Mid Suffolk, although it remains widespread in the Sandlings. The Grayling is an insect of dry sandy grassland, and has a generally coastal distribution. It also has a fondness for conifers on dry sandy heathland, and can be found in the Brecks as well as the margins of Dunwich, Tunstall and Rendlesham forests. Formerly, it was regularly found in the general countryside too, but the agricultural clay of High Suffolk no longer supports it, and the distribution maps have thinned out, with few sightings outside of the prime areas of Suffolk Coastal district. The maps below illustrate this trend, and show Graylings in only 6Â7% of the surveyed area now, compared to 13Â5% found over the nine years since the Millennium. The colonies of the Brecks have now become isolated. It is still recorded on three transects (Cavenham Heath in the Brecks, Fynn Valley and North Warren), but numbers are falling on all threewalks. Rob Parker 66 Cornfield Road, Bury St Edmunds, Suffolk IP33 3BN

Trans. Suffolk Nat. Soc. 45 (2009)


RUNNING HEAD 2008 BUTTERFLY REPORT

61

Grayling distribution

2000 to 2008 5 squares, (13Â5% of 1000 surveyed)

2008 single-year 37 squares, (6Â7% 0f 547 surveyed)

Trans. Suffolk Nat. Soc. 45 (2009)

2008 BUTTERFLY REPORT  

Rob Parker

Read more
Read more
Similar to
Popular now
Just for you