Report on 2007 Translocation

Report on 2007 Translocation of Silver-studded Blue, Plebejus argus, to Blaxhall Common, Suffolk.

This report covers the translocation of Silver-studded Blue to Blaxhall Common SSSI. The activity was organised jointly by Butterfly Conservation (Suffolk Branch) and the Suffolk Wildlife Trust in pursuance of the objectives of the Suffolk Local Biodiversity Action Plan [1]. The active phase was completed on 8 July 2007.

Approvals.

The necessary consents were obtained in advance from Natural England, Butterfly Conservation Head Office, landowners at the donor sites - (R.H & R. Paul for Sutton and Hollesley Heaths SSSI (Lower Hollesley Common), and RSPB for MinsmereWalberswick Heaths and Marshes SSSI (Sawmills site), and at the receiving site, Blaxhall Parish Council. The detailed proposal was submitted to Natural England [2] on 30 Jan 07. A final check for the presence of Lasius ants was successfully conducted on 9th May, and letters of consent [3] were issued on 13th June.

The Plan.

The proposal specified two separate translocations, one from each of Lower Hollesley and the Sawmills colony near Minsmere, one to be conducted at the peak flight period, and the other two weeks later. The intention was to move as many mating pairs as possible, with the balance made up to 30 adult butterflies from each donor site. See [2] for full detail.

Timing.

Following an unusually hot April, the 2007season began early, and the first Silver-studded Blues made their appearance in Suffolk on 4th June, two days earlier than ever previously recorded. In view of this, the first translocation was conducted on 18

June.

First Translocation – 18 Jun 07.

A SWT/BC volunteer team of 5 entered the Sawmills site at 11:30 with the weather as forecast: 17C and overcast with a light breeze. Initially, the numbers of butterflies were low, particularly females, but by 12:30 the day was warmer, with a few sunny intervals, and we had little difficulty finding roosting Silver-studded Blues and potting them. Shortage of sun

meant that there was limited flight activity, and we saw no pairings, so we concentrated on collecting females. Their condition was variable; some were very fresh, whilst others had evidently been on the wing for some days, so the chances are good that they had already mated. The proportion of partly blue females (rather like the named aberration var. masseyi) seemed higher than normal, but perhaps this was noted simply because we were handling and inspecting them, rather than just counting them. The 2007 flight season was running early; there were almost as many as would be normal at the peak of the season.

The butterflies were collected in clear plastic pots and transferred to a fine mesh enclosed cage, which gave them an opportunity to pair, but none of them did so. In all 20 females were taken, and 10 males. Some rejection behaviour was noted, suggesting earlier pairing had occurred. Fortunately the threatened showers avoided Minsmere and Blaxhall, where we arrived and made the releases at 14:30 at three pre-planned spots:

1. The open area of short Erica that was once an informal car park at TM3791 5675. Here we released 3 males and 7 females.

2. The area of the ancient mound at TM3789 5689. 4 males & 8 females were released.

3. The open area formerly used by travellers at TM3781 5692. The remaining 3m & 5f were released.

Behaviour on release was encouraging. Although a few drifted off in the westerly breeze, most remained feeding on the Erica very close to the release sites, which are separated by about 100m. Each is close to a recently foraged area with pioneer growth already visible, and ant activity in evidence.

Second Translocation - 3 Jul 07.

The pre-planned translocation from Lower Hollesley was executed on 3 July in bright weather during a generally showery week. All 30 butterflies were taken from Lower Hollesley "A" , where they were sufficiently abundant that there was no need to visit the "B" colony. One mating pair was found and moved in cop. The balance comprised 19 females in variable condition and 9 fresh males, making another batch of 10m & 20f in total. These were released at Blaxhall Common from 12:00 to 12:30; using the same 3 release points as the first batch 15 days previously. Most remained in the immediate vicinity of the release points, just resting on heather. After the releases, a single male was encountered in the north of the common, presumably a survivor from the 18 June release.

The Team

The translocation was organised jointly by the Suffolk Branch of Butterfly Conservation and the Suffolk Wildlife Trust.

The team involved in this project includes a few permanent members of staff of Butterfly Conservation, the Suffolk Wildlife Trust and the RSPB, but the majority of the team were volunteers from those organisations and the Suffolk Naturalists ’ Society. Although the actual translocation was completed in 2007, the ongoing monitoring and site maintenance will require an enthusiastic volunteer team for years to come. The existing local SWT group at Blaxhall Common will continue doing the site management, and their leader, Terry Peake, will also organise the new transect walk. Those who have participated to date include:

Blaxhall SWT Volunteers T. Peake (Warden) A. Chapman J. Day S. Exton J. Forbes M. Forbes A. Freer S. Freer G. Haywood-Smith L. Merrion F. Pynn A.Salisbury H. Taylor R. Turner

Butterfly Conservation M. Austin M.Farrow J. Foster R. Foster A. Johnson B. Johnson S. Keeley R. Parker S. Peck G. Proctor S. Wolfe

SNS Mr. Blacker Snr N. Blacker N. Cuming N. Mahler

Other SWT N. Mason (Hollesley Warden) K. Thacker S. Thacker

Staff Participants R. Harvey (RSPB), M. Kemp (RSPB), D. Kidney (Natural England), D. Mason (SWT), S. Hearle (Butterfly Conservation)

Early Monitoring.

During a walk round the intended transect route 10 days after the first translocation, David Mason (SWT) found one male and one female on Section 4, northwest of the most northerly release site. The follow-up visit on 8 July was a success, and also found that area occupied. A team of 19 BC/SNS volunteers walked the intended transect route on a broad front, and found as follows (5 days after the second release):

Release Point 1. One male was found in the immediate vicinity, and a second flew through later.

North-western end of transect. Two males and two females were found roosting in medium height heather along Section 4 of the transect, close to the stump, which is 100m west of Release Point 2.

Release Point 2. At least 8 (approx 4f & 4m) were found resting within 20m of Release Point 2, which is the patch of short heather formerly used by travellers. As we moved into the area in the sun, they began to fly, so we avoided double counting, but there were probably more than just 8. Most were roosting on Calluna rather than the Erica which was in flower, and always nearby.

Release Point 3. The hillocks of the tumuli looked suitable to the human eye, but had been abandoned by the butterflies, possibly because it is the highest point of the common, and catches the wind.

The overall impression was that the butterflies have moved a little northwest, but are settled into the habitat. It is encouraging to have found at least 14, five showery days after the release. Doubtless others remained on unvisited parts of the common. We must hope that plenty of eggs have been laid.

A few informal visits produced sightings in the following weeks, but by 26th July, unsurprisingly, there were none left on the wing.

Future Monitoring.

A single-species transect has been established, and volunteer walkers found. They have walked it for the remainder of this season for familiarisation. It begins further south than the first release point, and stretches further northwest than any of the 3 release areas. Next season ' s results will show whether the translocation has been an initial success, and future years will determine whether the colony becomes properly established and extends. Under the relevant guidelines for Introductions and Translocations [see Table on page 15], we are encouraged to continue monitoring the site for 10 years.

Site Management.

Already a SSSI, the site is managed in pursuit of the Lowland Heathland habitat action plan [4]. The common has been brought up to a suitable condition for Silver-studded Blue by the endeavours of SWT staff and a team of local volunteers. Heather cutting, silver birch removal, bracken control and the creation of bare areas have all been necessary. This work has been done largely by local volunteers, acting through SWT, and with the financial support of SITA (landfill grant) and Natural England. A continuing commitment to heathland management is essential to maintaining the right habitat for the butterfly.

Volunteers.

This project has harnessed the endeavours of the existing team of Blaxhall Common volunteers, led by Terry Peake, and of active members of the Suffolk Naturalists ’ Society, Butterfly Conservation and the Suffolk Wildlife Trust. At least 33 individuals contributed to work during the first

year.

Financial Support.

A grant from the Connect Fund, administered by the Suffolk Coast and Heaths Unit, supported project expenditure. This included volunteer expenses, an interpretation board, and the production of this report. Publicity.

Press releases resulted in two articles appearing in the Eastern Daily Press and one broadcast on BBC Radio Suffolk. These undoubtedly had an educational effect on the public, as well as drawing attention to the good work being done by SWT and Butterfly Conservation.

Lessons Learned.

It was not possible to collect mating pairs on the days that the translocations were planned, and this could mean that fewer eggs were laid than we would have wished. Partly, this was the result of setting a date in advance and finding that the weather, whilst meeting our minimum criteria, fell short of perfect mating conditions. Better results might have been achieved with a more flexible approach to timing.

Enough Eggs?

Conceptually, our two batches of 20 females might have laid 100 eggs each, leaving a total of 4000 ova to overwinter. Allowing for 90% predation in the early stages, 400 adults might emerge in 2008, 200 being females; a five-fold increase over the number released in 2007. That would be a firm foundation for the future, but such projections can be over-optimistic!