Annual Report on Silver-studded Blue 2005

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 33 if the introduced Purple Emperor is included.

Analysis

Relative scarcity can be deduced from a count of the number of tetrads from which each species has been recorded. Our rarest native butterflies are usually the 3 BAP species, followed by the White Admiral. This year's league table reflects a numb~r of changes, with Clouded Yellow appearing high up as a result of the poor migration season. Encouragingly, White Admiral and Holly Blue are much improved, but worryingly, the Wall was only found in 6% of the squares surveyed. Year-on-year change is not simple to quantify: a straight tetrad count is less meaningful than the percentage of survey squares in which each species was found. Neither measure assesses a butterfly's abundance at its breeding sire as accurately as the "index" derived from transect walks.

Transects

Derailed data was submitted for the established transects at North Warren (Rob Macklin), Fynn Valley (Richard Stewart), RSPB Minsmere (Robin Harvey), Bradfield Woods (Steve Hunt), Center Pares (Graham Hersey-Green), Cavenham Heath (Michael Taylor), Walberswick (Adam Burrows) and Bury Sr Edmunds (Rob Parker). Four new transects have also produced results this season: Wolves Wood (Mark Nowers), Newsons Farm (Frances Bee), Barham picnic site (Nick Dickson) and Upper Abbey Farm (Trudy Seagon), bringing the roral to 12 full transects and 3 single-species transects. Special thanks are due to all those transect walkers for their regular monitoring, which provides an objective abundance count as well as site-specific observations, and flight times.

Annexes [to be published later]:

Scarcity 2004 & 2005 Analysis of 11 Years to 2005 Derailed reports for BAP species. Silver-studded Blue Dingy Skipper and White-letter Hairstreak

Annual Report on Silverstudded Blue for 2005

by Rob Parker

Season

2005 started late by comparison with the past 2 s.easons. A cool, wet spring protracted larval feeding, and the butterfly was not on the wing until June 18th, compared with June 7th in 2003/4.

A summer interrupted by heavy rain spoiled survey effort as well as depressing the peak figures at most colonies. Relatively low temperatures reduced the prospects for colonising activity late in the summer.

The Counts

The main count at Minsmere had been planned for June 20th, and a team of volunteers counted the two main colony areas until it became clear that the population was predominantly male, and well short of its peak. Unfortunately the re-count two weeks later was hit by torrential rain, and the third attempt was past the peak, so the results were unsatisfactory. Most other colonies were adequately counted, although recorders had to make several visits to get reasonable results.

An initiative to inuoduce mini transects at Minsmere got off to a poor start, but was trialled sufficiently to devise a workable plan for future years.

Results

The results for the season's counts are tabulated below, and are generally .Jess complete than usual. Although the results for Minsmere, Walberswick, Westleton Heath and Common, Upper and Lower Hollesley are not high, they do not give cause for concern. Furthermore, there is some encouragement from the recently established colonies at Parsnip Plantation and Rushmere Heath, both of which have shown a gentle increase in numbers. Furthermore, overall distribution maps for 2005 show records from 17 tetrads, which is the second highest count since 1995. On the other hand, there was a population crash at Purdis Heath, and just one butterfly at Wenhaston Blackheath. Although the numbers at Mardesham Heath are higher (377) the downward trend does give cause for concern. These 3 sites need heather management, and are dealt with inruvidually below.

Purdis Heath

Visits by 3 separate recorders found no more than 6 Silver-studded Blue, and none were found on the' adjacent Golf Course. This is a serious crash from the recent past: 2004:63, 2003:86, 2002: l 08, and 2001:145. In his 2003 report to Suffolk Wildlife Trust, 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. It is salutary that just 2 seasons after this alarm, the colony is in crisis. A number of discussions and an on-site meeting were held to assess the strength of the ant colonies and to consider appropriate heather management plans for the forthcoming winter. le was felt that past forage harvesting had been the correct technique, but that an insufficient area of pioneer heather had been created. To enlarge the area suitable for egg laying in 2006, forage harvesting will be undertaken to extend the width of each tract of cut heather. Adrucionally, a fresh tract will be cut to the south side of the footpath through the "main flight area".

Martlesham Heath

The count of 377 includes one well-populated flight area where the heather is re-growing following an accidental burn, so the reality of a low count in other areas is somewhat concealed.

The area in need of cutting is enormous and beyond the resources of the Martlesham Conservation Group. If English Nature funds can be released to enable forage harvesting in the (privately owned) airfield area, the colony will have a future, otherwise the prospects are not good.

Wenhaston Black Heath

For the third year in succession, the population has been barely detectable, and Silver-studded Blue have been noted only in the traditional ilight area, even though other areas of pioneer heather are now available nearby. Habitat work by the Wenhascon volunteer group continues.

~t

Silver-studded Blue

by Beryl Johnson

Monitored Silver-studded Blue sites listed geographically from the North

Location North Grid Reference Date Observer Male Female 74 TM4074

Blackheath Wenhaston TM420749 Jui Richard Havard 1 0

TM4874

Walberswick Comm' NNR TM491752 29-Jun Adam Burrows 26 10 72 TM4472

70 TM4670

AldrinQham Walks TM464612 1-Jul Rob Macklin 179 38

68 TM4468

Westleton Heath NNR

TM4569 29-Jun Adam Burrows 137 39 Westleton Common TM44306870 3-Jul David Rous 175 77 Westleton Football Pitch TM44406880 3-Jul David Rous 25 15 Minsmere Westleton Walks TM459689 Minsmere Sawmills TM452692 Minsmere Football Pitch TM451691 Minsmere Natteriack Pond TM451693 Minsmere SW Como' 1 TM450694 Minsmere Pit Como' 2 TM457692 Minsmere SE Como' 3 TM457691 Minsmere Como' 20 N TM446683 Minsmere S Como' 3 TM456693 Minsmere Central Como' 3 TM453693

TM4668

Minsmere Powerlines TM461683 Minsmere North Bridlewav TM468687 Minsmere Potbrioos TM468689 20-Jun Mel Kemo 47 0 Minsmere North Grimstones TM462688 20-Jun Mel Kemo 368 37 Minsmere E Como' 13 TM468681 Minsmere Como' 13 track TM464681 Minsmere Como' 13 Tanktrao TM466683 Dunwich Heath TM468687 1&03 Jui David Sutton 1 1

Como' 20 South Gravel Pit

66 TM4466

TM445670 TM449669

46 TM3246

Upper Holleslev MoD TM33344723 11-Jul David Mason 159 33 TM3446 "Lower Holleslev ""A""" TM342465 2-Jul Richard Stewart 325 142 "Lower Holleslev ""8""" TM343461 2-Jul Richard Stewart 244 91 "Lower Holleslev ""C""" TM350460 28-Jun David Mason 22 2

44 TM2044

Rushmere Heath TM202448 14-Jul David Mason 8 2 TM2244

Martlesham Heath

TM2445 10-Jul Phil Smith not split TM3244 Parsnio Plantation TM32724579 11-Jul David Mason 17 1

42 TM2042

"Ipswich Golf Club, Purdis" TM208432 Jui Neil Sherman 0 0 Purdis Heath TM21204270 6-Jul Richard Stewart 6 0

40 TM2040 Total

217

176 252 40 0 0 0 0 0 0 0 0 0 0

0 0 47 405 0 0 0 2

192

467 335 24

377

Industrial Estate TM207419 6-Jul Richard Stewart 47 20

2005 Totals 1787 508

67 2672