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Brown Hairstreak in Worcestershire - Bulletin 35

October 2006

Dear Brownhairstreakers,

Despite the continuation of some half decent weather into early October, the two sightings on 24th September reported in the last ebulletin proved to be the last of the year. Looking back, it has been an interesting if somewhat unusual season. Compared to 2005, the butterfly was very late emerging with the first adult not being seen until 9th August (31st July, 2005).

Very, very few males were positively identified at all this year and the assembly trees, where we have seen adults over the last two years, were apparently unoccupied throughout the season. Evidence from our colleagues in Butterfly Conservation's Upper Thames branch suggested a switch this year away from ash in favour of oak, presumably in response to aphid abundance, and it may be that this happened in Worcestershire as well but we have no actual observations to support this.

Despite the late first sighting date, the first egg was seen on 12th August, four days earlier than last year, and many subsequent sightings were of egg-laying females. What we can say with certainty, is that there was no shortage of females with over 70 sightings reported in total which is undoubtedly a record for the county. Numbers peaked in the last week of August with no fewer than seventeen reported on 27th and twelve, two days later. The vast majority of these sightings came from Grafton Wood NR and the immediate surrounding area which is very rewarding for those of us who have put so much effort into creating suitable breeding habitat for the butterfly. Looking at the distribution map, however, we have adult records for only around 10% of the total number of 112 1km squares where eggs have been seen and I hope that next year we can encourage recorders to search further afield. Obviously, because the Brown Hairstreak is notoriously difficult to spot there is a tendency for people to gravitate to hotspots where they feel there is most chance of seeing the butterfly but, in terms of our wider conservation objectives, it would be helpful if time could be given to looking for adults elsewhere in the Forest of Feckenham. A good case in point were the discoveries, albeit accidental, reported in the previous ebulletin of adults at Trench Wood NR and near the M5 motorway. Incidentally, this latter record was incorrectly reported; the sighting was in SO9059 not SO9060 and on the eastern side of the motorway not the west! Apart from this, it was completely accurate!! It does remain, however, a new 1km square record and our most western sighting so far. For those wanting to know more about the history and current status of the Brown Hairstreak in Worcestershire, the article written earlier this year for the Worcestershire Record is now available via the website of the Worcs Biological Records Centre at www.wbrc.org.uk

One of the challenges we set ourselves this year was to try to get a feel for when most eggs were laid and we marked some blackthorn at the southern edge of Grafton Wood with this in mind. Eight eggs were initially found on 25th August and subsequent visits were made on 7th September and 8th October. On the second visit, all the original eggs were re-found but there was no sign of any additional eggs having been laid despite a careful search. However, by the time of the October visit while only seven out of the original eight could be relocated, a further four new eggs were found on nearby plants suggesting that egg-laying lasts well into September. This potentially is an interesting project which could be usefully repeated elsewhere within the butterfly's range but we really need a volunteer able to make more regular monitoring visits. This sounds like an ideal job for one of our local Hairstreak Champions and I would be pleased to hear from anyone prepared to give it a more systematic go next year.

The sighting at Trench Wood referred to above has prompted us to take a closer look at how we might improve the habitat there for Brown Hairstreaks and try to encourage more breeding within the main body of the wood. Blackthorn is presently very local at Trench and we hope, with the support of the Worcestershire Wildlife Trust, that we might carry out some new planting. As a first stage, Neil McLean, the Reserve Manager, has agreed to map the current distribution of blackthorn in the wood and identify some suitable areas. As mentioned in the last two ebulletins, we have a new supply of blackthorn whips available through our Nurturing Nature grant from the West Midlands Biodiversity Partnership so will earmark some of these plants for Trench Wood.

Over the last year or so, we have been very grateful for the support of Becky Lashley from the Worcestershire Biodiversity Partnership who has been a fantastic ally in helping us to reach the wider community including local schools. Unfortunately, Becky's Vision Mapping project is now coming to a close with the final three months spent drawing up vision maps for the nine parishes that make up the project area. These maps will then be open to public consultation before final approval and publication. Hopefully, part of the shared vision can be a landscape dominated by a network of wildlife friendly hedgerows and a countryside full of Brown Hairstreaks!

While the window for seeing adult butterflies on the wing may have closed for the year, there is now the opportunity to do your bit for Brown Hairstreak conservation by attending the regular work parties that take place on nature reserves within the Forest of Feckenham. As well as the Grafton work parties on the 2nd Sunday of the month, there is also a work party at Trench Wood on the 4th Sunday of the month meeting at the reserve car park at 10 am. New recruits always welcome.

Mike Williams,
Brown Hairstreak Species Champion