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. 
Area
No
Volunteers
Blkthorn status   previous year
Blackthorn management
000 - 025
37
 Steven,  Anne,  Sarah & Gerry
v good

025 - 050
91
      “         “          “            “
v good

B Glade
56
      “         “        
V good

B Glade 2nd
10
      “         “         
  ok

050 - 075
32
      “         “          “            “
 good

075 - 100
27
      “         “          “            “
  good






100 - 125
16
Richard, Paul, Alan and Chiara
poor

125 - 150
20
     “        “         “           “
poor

150 - 175
20
     “        “         “           “
ok

175 - 200
32
     “        “         “           “
good

Bracken Patch
2
Richard and Paul
ok






200 - 225
66
Madeleine, George, Alan
v good

225 - 250
32
                          
v good

250 - 275
01
      “     “     “       “      “
   ok

275 - 300
10
     “      “     “       “      “
v poor

Shallow Pool
03

  poor






300 - 325
02
David and John
    ok

325 - 350
02
     “           “          “           “
  poor

350 - 375
00
     “           “          “           “
  v poor

375 - 400
01
     “           “          “           “
  v poor






400 - 425
01
Nikki
  poor

425 - 450
07
     “          “         “         “
  poor

450 - 475
07
     “          “         “         “
  poor

475 - 500
08
     “          “         “         “
  poor

       Total
483
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.