Eastern Subalpine Warbler at St Davids Head

I was working on Skokholm on 13th April when I got a call from Ken Thomas, a long-time visiting birder from Neath, to say he had found a Subalpine Warbler out at the Head. Tragically (for me) I was stuck, not due to leave for another day so I contacted local birders to pass on the information and left it at that except to put a belated note and grid reference on the Pembs Blog when I reached the mainland. I also had a look around the area Ken specified as soon as I could but no luck. I did try to contact Ken again but failed. I spoke to him again several days later and he told me he had taken some photos and we made vague arrangements to meet up which never came to fruition and it wasn't until I bumped into Ken and wife Ann at the Head again that we spoke some more. I asked a bunch of questions and ran through some features differentiating Eastern Subalp from Western. I must have hit a chord because Ken sent me a text after looking at the pics again and then dropped by the house with his camera. I wasn't at all surprised to see what looked like a pretty good candidate for an adult male Eastern Subalpine Warbler. Incidentally, there was another Eastern bird reported from Shetland around that time as I recall.

These are all Ken's photos, I've cropped, slightly adjusted exposure and sharpened them a little but nothing else.

Photo 1

Photo 2

Photo 3

Photo 4

Photo 5

Photo 6

The first thing that struck me was the intensely coloured dark purply reddish throat, sharply demarcated from the rest of the underparts. The tone is a kind of brown ochre red rather than orangy/pink as might be expected for Western. Also in Western the strong colour should extend onto the flanks and contrast with the pale belly. In this bird the flanks are pale, apart from a very few streaks on the upper flank/breast and, as far as I can tell, concolourous with the rest of the underparts. Photos 2, 5 and 6 leave no doubt about how well marked the sub-moustachial stripe is. It's pretty stonking, another good feature for Eastern.

I think the bird is an adult rather than 2nd cal yr since the orbtal ring is strongly coloured orangy-red around a darker iris. Given this then the wing coverts, secondaries and tertials might be expected to be warmer brown in Western which is also darker blue-grey on back/mantle/head than Eastern, which is supposed to be a paler bird re the upperparts generally and this bird is quite a pale blue-grey with rather grey-brown flight feathers, the head appears darker than back and mantle at times, (though a caution that this is based solely on the photos and, it seems to me, photos can sometimes be problematic for judging subtle colour tones).

A recent paper by Lars Svensson (British Birds Nov 2013) set out new identification criteria re the pattern of T5 which is unfortunately no use using the photos we have here. It also suggested a three way split into three species Western, Eastern and Moltoni's including a re-ordering of scientific names.

At present BBRC examines records of Eastern Subalpine Warbler, there having been 43 accepted records to the end of 2013. There has been one previous accepted record in Pembrokeshire, on Ramsey in May 1993.