Annual Transect Egg Count at West Williamston, Pembrokeshire

West Williamston’s annual egg count this year was carried out by 15 enthusiastic volunteers on a damp, grey Pembrokeshire day.  Travelling from all over south Wales.  The team also welcomed several new ‘hairstreakers’. 

The total number of eggs found was surprisingly high compared to reports of lower counts from other areas.  Blackthorn management has continued to be carried out on a rota basis by Nathan Walton, WTSWW officer and his volunteers, and it is worth noting that the areas where eggs laid were most concentrated correlates directly to the areas where most males were seen during August and September.

Aerial GPS locations of 2015 Brown Hairstreak eggs found along the foreshore transect (and beyond) with thanks to Stephen and Anne Coker

West Williamston SSSI Annual Brown Hairstreak Egg Count 
Sunday December 6th 2015. 
Blkthorn status   previous year
Blackthorn management
000 - 025
 Steven,  Anne,  Sarah & Gerry
v good

025 - 050
      “         “          “            “
v good

B Glade
      “         “        
V good

B Glade 2nd
      “         “         

050 - 075
      “         “          “            “

075 - 100
      “         “          “            “

100 - 125
Richard, Paul, Alan and Chiara

125 - 150
     “        “         “           “

150 - 175
     “        “         “           “

175 - 200
     “        “         “           “

Bracken Patch
Richard and Paul

200 - 225
Madeleine, George, Alan
v good

225 - 250
v good

250 - 275
      “     “     “       “      “

275 - 300
     “      “     “       “      “
v poor

Shallow Pool


300 - 325
David and John

325 - 350
     “           “          “           “

350 - 375
     “           “          “           “
  v poor

375 - 400
     “           “          “           “
  v poor

400 - 425

425 - 450
     “          “         “         “

450 - 475
     “          “         “         “

475 - 500
     “          “         “         “

This is the total written in diary on the day, after approximately 2 hrs

NB – Stephen and Anne Coker took GPS readings for all at end of December = 494
           Last year’s transect count total (2014) was 232

Egg survival summary from 2015 at West Williamston

Realising that I haven't yet written up the results of last winter's egg survival project I am posting a brief summary now before a much more satisfactory post with the results of our annual foreshore transect last month.                                                                                                              The chosen survey site was on the north side of top field, adjacent to the reserve’s small car park

The original aim of the survey was to try to assess the number of eggs predated by ‘unknown’ predators over the winter months, in order to establish base information for future surveys, including identification of possible predators.  

The survey was begun in September 2014, with fortnightly then monthy checks.  By March 2015  40 of the established 196 eggs were missing or predated, with a further 17 eggs found without tags. (A further 100 eggs were lost under different circumstances - see below).

The overall total of eggs surviving therefore was established as 78%. 
This compares well with survival counts carried out by David Redhead in the Midlands where survival rates appear to be slightly lower, being in the region of 75%. 
Could these be possible predators?
This survey was flawed and after 2 months there was a serious problem.
  • horses that graze the field broke managed to 'predate' several eggs along with the tender twigs they were on.
  • 85+ eggs were lost when the ‘over-enthusiastic’ contractor employed to top the meadow failed to see the young tagged Blackthorn and removed them too. These numbers were not included in the 196 eggs surveyed mostly by David Redhead, in a much denser area of blackthorn inside the fence.

This is an important learning curve, and the next egg predation survey will be carried out  with tighter limits and guidelines. Loss by horse and machine were not anticipated.
Encouragingly we established that the predation/egg loss was steady over the months from October to March.   In the past one of the 3 small sample survival counts had indicated that increased predation may have taken place very soon after the earliest eggs were laid i.e. possibly taken by  Warblers. 

These 3 old studies had resulted in  a higher survival percentage than the current study – they were all in the 80% band.  

Another late Brown Hairstreak sighting in S W Wales......further to Thursday's post, yesterday, I came across another female (in fairly fresh condition) flying below us on a habitat hotspot in Cwm Hiraeth, near Newcastle Emlyn in NW Carmasrthenshire - Teifi valley, where the species still thrives, largely due to high concentration of small holdings and low penetration of modern agriculture.

Anyone, who can contribute to other request on Thursday re growing blackthorn from seed, please share with us.

Whilst working out a coppicing plan, I disturbed a Brown Hairstreak this afternoon in a deep valley in a field of one of our few remaining southern Carmarthenshire sites. We've apparently gone from 56 sites in 2006 within 15kms of Carmarthen, down to just 6 still occupied. This includes one large site, part of which we manage.

On a related matter, although coppicing to regenerate via suckering is our main tool, the owner of one of the managed sites also wants to grow his own Blackthorn from seed (sloes) in his own tree nursery, so that they can be planted out into new hedges, and is asking for any tips on germination, growing etc. Does anyone have or can point me to suitable experience/advice please. Thanks.


I visited Grafton Wood yesterday for the first time since the cloudy, and hence somewhat disappointing, Open Day eight days ago. However it was a beautiful sunny day yesterday and I was rewarded with five sightings of separate female Brownies.

It was fairly chilly when I first arrived in the wood at 10:30, even though it was sunny, but it gradually warmed up and about an hour later I had my first sightings of two females in a large overgrown hedgerow, to the north of the main pond.

Half an hour or so later I bumped into Steve Williams and he told me he'd seen two females too, but in different locations to mine. We both went to investigate the area where he'd had his sightings and almost immediately found one of the females searching the blackthorn for suitable egg laying sites.

After crawling up and down various tiny blackthorn stems, this one (presumably?!) seems to have
got confused and I watched it lay an egg on a Field Maple sucker!

Walking back towards the pond, Steve then spotted another female flying and basking on a different stretch of hedgerow. No more sightings at the pond, although I'd earlier met someone who'd seen a female in an Oak tree there first thing in the morning at around 9:30.

At about 2:15 Steve and I both decided to call it a day and walk back to the car park. However
on the way back, Steve pointed out the area where he'd had his first sighting of the day - on a hedgerow roughly halfway between the church car park and the wood. Believe it or not, within a few seconds there it was - flying out of the hedge and stopping to bask just in front of us.

This was the fifth separate female I'd seen on the day, and shortly afterwards I spoke to another guy who'd had a sighting of a female right in the middle of the wood. That one, together with the one seen early on near the pond, plus my five sightings, meant that at least seven separate female Brownies had been seen in or near the wood yesterday. Evidence that the flight season is still very much alive!

Blasted to Kingdom Come...

The Gloucestershire - Wiltshire border suffers from a foul and abusive climate...

The sun reappeared on Friday August 28th, after several days of wind and rain.  I went out streaking, of course, but struggled to see a single battered male before cloud billowed up around 10.30.  My guess is that the males have been blasted away here, though there certainly should be egging females lingering on.  

The North Wilts flight season seems to end early - the butterflies are usually gone by the end of the first week of September, after starting circa 26th July (25th July this year).  Males disappear around 20th August leaving a tail of females.  

The brevity of the flight season here may have something to do with habitual foul and abusive weather during August...

Had August been better I would have returned to Shipton Bellinger in pursuit of that elusive century...  As it is, I'm going to Knepp Wildlands in West Sussex for a few days this week.  Knepp also supports a strong population.  Watch this space...

Weather-beaten but undeterred

After a highly promising start to the season, Pembrokeshire Brownies have been battered by nine successive days of storms, wind and rain.

Saturday 29th August provided a short window for any remaining betulae to get down to business again, but in a four hour visit between 10am and 2pm, I only managed to find one solitary female doing so, although she did provide a fascinating 20 minute tutorial regarding behaviour.

Previously, I'd only ever seen females lay eggs in isolation, but this one laid two, one after the other, on the same fork of a blackthorn sucker.

The images below show this process taking place, with the two freshly laid eggs then photographed immediately after the butterfly had moved away. This individual had a deformed right hindwing which, whilst unfortunate for her (though it didn't seem to impair her flight), allowed the abdomen to be clearly seen during ovi-positing.

She was found at 1.33pm and remained in ovi-positing mode until 1.54pm when she flew out into the open field before veering back round towards the shrub line whereupon I lost sight of her.

This site really needs some fine weather over the next couple of weeks. The Hairstreaks are there (albeit in reduced numbers thanks to the storms), but they are largely imprisoned by the atrocious conditions, meaning that egg-laying is simply not on the agenda except for during rare and brief bright periods.

The big descent has started out west

15th August 2015
On day one of the Hairstreak Weekend at the West Williamston WTSWW Reserve in Pembrokeshire 27 Brown Hairstreaks were observed - a record for the site in one day - we see Matthew's 76 as a challenge for the 2016 event.
Our 27 were also mainly males spread across two sets of ashes and an isolated ash but 5 were low level females of which 3 were observed egg laying. After they had disappeared 15 bright white shiners were discovered including one triplet and one doublet.
One set of ashes were under surveillance from 07:30am and the first male flight was observed at 08:05am. For the next two hours things were pretty hectic with three dog fights observed when a pair of males spiralled high above the ashes. Things began to quieten down after 10am and the last male flight was observed at 10:40am. The first female descended just before midday but it was just over an hour before egg laying was observed. All went quite when clouds rolled over the sun about 2pm.

16th August 2015

Day 2 was a shadow of Day 1 - only 10 Brown Hairstreaks seen - all up in ashes and relatively lethargic and definitely no more egg laying. The weather on the two days was similar. Typical betulae behaviour - one day all guns blazing, the next spent in harbour refuelling.

17th August 2015
Another visitor reported a total lack of action at West Williamston but meanwhile they were putting on a show at the Teifi Marshes WTSWW reserve in north Pembrokeshire with four sightings. Three low level nectarers on hemp agrimony were seen by Maggie Sproule & Sarah Bebb. From Maggie's photos two were definitely males and the third almost certainly so (only underside seen). The fourth was heading for the hemp agrimony when the two incumbents decided to see it off.

Below is a non-nectaring female at West Williamston photographed by Jerry English on 15th August and a nectaring male at Teifi Marshes phtographed by Maggie Sproule on 17th August.

As far as I can ascertain Teifi Marshes is the only site in Wales where nectaring Brown Hairstreak are seen - can anybody please explain this to me?

11th August - Grafton Wood

Apologies for the lateness of this!

Had a successful day at Grafton Wood on 11th with Simon Primrose and Richard Smyth. 4 different Brown Hairstreak (3 male, 1 female), all in different areas of the wood (one of these seen by John Tilt). 3 Small Copper, Purple Hairstreak, Brimstone, Painted Lady, multiple Silver-washed Fritillary, Common Blue and the usual suspects - Peacock, Meadow Brown, Gatekeeper, Ringlet, Small White, Large White, Green-veined White. Also found a poor White-letter Hairstreak that was in the process of being chomped by a crab spider.

A quick reminder to everyone visiting over the next few weeks - the orchard hedgerow is still out of bounds and should be avoided. It is NOT on a public footpath and is private land. The Brown Hairstreak is very widespread within the wood and can literally be seen anywhere! To aid new visitors, there are now signposts and maps up showing the best areas to find the Brown Hairstreak.

The Grafton Wood Open Day is on 30th August this year and is bound to be a great social occasion, combined with some good sightings of Brownies. Hope to see some of you there :)