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 6^th 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

Read More

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.  

Read More