Friday, 27 July 2018

They were there all along!

I unfortunately couldn't make the Lake Vyrnwy daytime event earlier this month to look for Welsh Clearwing, but as RSPB Warden one of the jobs on my to do list when I got back from holiday was to survey a couple of plots for the clearwing in the same area.

1+ BOS score
No BOS score
This survey involves looking at individual trees and taking measurements to determine whether they are suitable for Welsh Clearwing and make an assessment as to what management we could do to improve the tree. As mentioned in Sue's blog of the event, clearwing required the lower trunk to be exposed to the sun and therefore we remove some of the lower overhanging branches. There is a score we give each tree which is called the Branches Over Skyline (BOS) score that is a figure between 0 and 8. Splitting the tree into eighths (if looking down on it) you need to decide how many segments have a gap between the lower branches and the horizon. To make the tree favourable for clearwing it should have a score of 4 along with a girth (circumference) of 100+cm.

Welsh Clearwing exuvia
With no signs found during the event I didn't have my hopes up for finding anything, so when I came across a tree that was riddled in old exit holes and spotted the distinct orangy exuvia protruding from the bark I was rather surprised and pleased! But even more surprisingly was the fact that I found a total of 9 exuvia on this single tree. I didn't find anymore signs during my survey but I was only surveying specific areas so there could have been more elsewhere. Hopefully these 9 adults will have had a successful breeding year and we will have more to find in the future!

Denisia similella
The excitement didn't finish there though! While walking through the wood I happened to look down on my survey sheet and noticed a small micro moth sitting there. A quick look revealed it to be Denisia similella which I stumbled across 3 years ago while doing the same survey. In 2015 it was considered to be a first for Wales and we at the RSPB soon nicknamed it 'Dennis'. So I'm assuming this to be the second record and evidence that there must be a small population in the area.

Gavin Chambers, RSPB Warden


  1. Top finds, Gavin!

    It's good to know both species are still around - seems like we must have just been unlucky with the clearwings for the event.


  2. Well done Gavin - and interesting to hear about the BOS score too. I'm sure everyone will be sorry to have missed seeing them, but will also be really glad to know that the Welsh Clearwings are there after all.
    A great find!

  3. Yes, a good find Gavin, well done, as Sue has said it's good to know that the Welsh Clearwing is still in the county.