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Brown Hairstreak in Worcestershire - Bulletin 25

March 2006

Dear Brownhairstreakers,

Sorry that early March has rather crept on to mid-March before I have managed to get round to the latest Bulletin but since my return from holiday I have needed to give priority to a promised article for the newsletter of the Worcestershire Biological Records Centre. This article tells the story of the Brown Hairstreak in Worcestershire so far and hopefully will provide a useful reference for all those concerned about the conservation of this beautiful and scarce insect. The article will appear in the next issue of the "Worcestershire Record" which is due out in April. The newsletter is available by subscription only (min. £10 per year) from the WBRC, Lower Smite Farm, Smite Hill, Hindlip, Worcester WR3 8SZ and is extremely good value. Alternatively, the article can be accessed via their website www.wbrc.org.uk although it may take a further time before it is posted.

While there may not have been a Bulletin for a few weeks, this certainly does not mean a lack of activity on the recording front. In Bulletin 23 I laid down the very optimistic challenge of whether we could reach the magic ton of squares for the Brown Hairstreak before the end of the winter. Thanks to the efforts of principally Trevor Bucknall over the last few weeks, we have amazingly achieved this and more. At the time of writing we are now up to 109 1km squares, a 100% increase on the number of known squares since this time last year - an absolutely fantastic effort and a big thank you to all our local Champions who have helped us reach this incredible figure. Amongst the new records, were 2 eggs found at last in Trench Wood which is the first confirmed breeding there for over 100 years! Trench Wood now becomes the fifth Worcestershire Wildlife Trust reserve to hold Brown Hairstreaks.

For those who are marking up their own distribution map, the new squares are SO9258/9259/9360/9460/9560/9561/9661/9359/9562/9662/9155  and SP0159/0261/0161/0260/0259/0361/0262/0258/0357/0355/0356/0256.

This increase in records over the last two years is very apparent from the attached map (with thanks to Bert Reid). The light blue circles represent the known distribution in 2004, the yellow circles represent squares added in 2004/5, while the brown circles are the squares added over the past winter.

Perhaps the most fundamental question, however, is whether what we have seen particularly over the past couple of years in terms of new records is just a reflection of increased recording effort or represents a genuine expansion of range? It is difficult to be sure and probably the answer is a bit of both. Certainly, the local Brown Hairstreak Champions scheme together with the Vision Mapping project of the Worcestershire Biodiversity Partnership has recruited new recorders who have been trained and encouraged to search for eggs. It is also true that we have looked for eggs in areas where we would not even have considered looking five years ago and, each time we have been successful, it has encouraged us to widen our search area still further. I do also feel, however, that the good management around the core area of Grafton Wood and nearby woods has helped to build up population numbers in a way that has aided dispersal and we have found eggs this winter in areas where we have previously drawn a blank. As far as the wider countryside is concerned, there is still a long way to go before Hairstreak-friendly hedgerow management becomes the norm (in fact one of the new hedgerows where Trevor recently found eggs had been flailed a week later!) but there is no doubt that our partnership with DEFRA particularly on the back of the new agri-environment scheme is bearing fruit and we are seeing increasing numbers of landowners joining the scheme. One of the participants on our most recent training day has already reported that he found Brown Hairstreak eggs on his farm at Bradley Green and now wants to make sure that future management of his hedges will enable the butterfly to thrive.

The other question of course is just how wide is the distribution of the Brown Hairstreak in Worcestershire and at what point will we reach the limit of its range in the county? This I guess is really the $64m dollar question! My own suspicion is that we are not there yet and there are almost certainly further squares to be added. It is important to recognise, however, that we are still talking about a butterfly with a very limited range in the county and, despite all the additional records, the Brown Hairstreak is still very much restricted to east Worcestershire. As a number of recorders will verify, finding eggs is not easy and, while we have documented our successes in this Bulletin, we are not always successful and many squares have been searched which have failed to turn up eggs. Despite the best efforts, for example, of Becky Lashley and the children from Himbleton 1st School on their egg hunt in February, the square around the village is still blank. There are also still gaps in our distribution map around Crowle and Bishampton where our searches up to now have not been successful. Today was another good case in point, when I explored the length of Bredicot Lane from Spetchley X-roads finding lots of super blackthorn but I was almost into Crowle before I recorded my first egg. Time is running out for this season and we have perhaps just another couple of weeks to search for eggs before the blackthorn is in blossom. Come April, it will be time to start looking forward to the Grafton Wood open day on 23rd and our summer programme of events. This year, we plan to follow up on our Brown Hairstreak larval studies of 2005 beginning with a Caterpillar Crawl on Sunday, 28th May, meeting at Grafton Flyford Church at 11.00 am. We have marked up a large number of eggs in preparation for this event so it should prove a good opportunity for everyone to get their eye in on finding caterpillars.

Mike Williams,
Brown Hairstreak Champion