By Yoav Perlman
mandtii Black Guillemot featured on Birding Frontiers in the past – see here and here. It also featured in Martin’s Challenge Series – Winter book. While to my understanding previous claims (e.g. East Yorkshire 2013, Cumbria 2013 and maybe a couple more) were abnormal arcticus rather than mandtii, this recent bird found by the sharp Dave Roberts on December 7th off Cut End in Lincolnshire does tick all the boxes and is a strong candidate to become a first for Britain.
Just a quick taxonomic reminder: Black Guillemots can be divided into two distinct groups – High Arctic (mandtii, from Arctic E N America across the arctic rim via Svalbrad to NE Siberia and Alaska) and Low Arctic (arcticus N America and W Europe, islandicus Iceland, faeroeensis Faroes and grylle Baltic). As far as I know nobody has any current plans to split them, though some years ago AOU treated them as separate species for a while. However, I find this a sexy taxon, that brings to mind eiders, Ivory Gulls and other stuff Martin loved to study. I should go and see it…
These are the first images I saw of the bird, by Graham Catley on December 9th. HUGE crops, taken in adverse light and weather conditions, they give the feel of a ‘proper’ birding experience!
First photo – on the water. Striking white appearance! Head is almost all white with just a little bit of dark feathering in the top crown. Very white mantle and rump too. The big white wing patch is completely white as well, with no dark coverts.
Then it took off – and revealed the diagnostic wing pattern. First the underwing. Limited black on remiges (primaries and secondaries) – arcticus tends to have all black remiges.
Upperwing pattern, already visible in these difficult shots, ends the discussion IMO. The white primary coverts are diagnostic for mandtii. Some mandtii have white bases to primaries too, in a pattern resembling skua underwing, but not all. The pattern shown by the Lincolnshire bird, creating a ‘pointed’ wing patch rather than oval, is similar to Svalbrad birds from Dan Brown’s post.
Next day, Steve Gantlett got better photos of the bird – still heavy crops in bad light conditions, but the features mentioned above become very clear in these pics. Snow white! Just a small greyish cap:
White median primary coverts are diagnostic. Interestingly, in these photos delicate pale primary bases can be seen:
White bases to primaries and secondaries, extending the white part of the underwing, are beautifully pictured here. Again, hint of white primary bases in rear wing:
For reference, here is the plate from Challenge Series – Winter. Sorry about the lousy scan. Drawings by Ray Scally.
Oh, how Martin would have loved this.
Many thanks to Graham and Steve for allowing me to use their great photos here.