Arctic Guillemot ssp. hyperborea

Identification possible?

I’m back on 13th May on  Hornøya Island, Varanger, by myself for the best part of 4 hours. Just a wonderful time amoung the auks. Specifically Arctic Guillemots, Razorbills, Puffins and Brünnich’s Guillemots. Also Shag, argentatus Herring Gulls (including the kind of pale “is it a hybrid” types we get in winter in Britain). Otter, White-tailed Eagle, Scandinavian Rock Pipit and a lone Chiffchaff all add to the interest. Here’s a taste ; )

One which I spent a bit of time on were the Arctic Guillemots, ssp. hyperborea. In Britain we have southern (ssp albionis) and Northern Guillemots (nominate aalge). Very crudely I think the former breed in England and Wales, the latter in Scotland. N. Ireland probably has a bit of both (mostly Northern). Please correct if wrong! I found the wing of an Arctic Razorbill (nominate ssp. torda) at Cley, Norfolk back in the mid 80’s (ssp. islandica breeds in Britain).

The more northerly breeding Razorbills regularly head south in winter. The only way you can tell them though is on wing measurement. Hence tide line corpses are the normal means of their discovery. Back in the day, mine was about the 7th British record, though I think in reality they are regular in the North Sea.

Arctic Guillemots however don’t move so much (BWP) and seem to be genuinely rarer in British waters. The ‘Birds of Shetland’ (Pennington et.al.) lists just 3 records attributed to hyperborea based on measurements of tide line birds. I know there is a clinal aspect to characters and some features (such as extensive dark underwing ‘spotting’) while commoner in hyperborea can regularly be found in other forms.

Nevertheless, have a look at these:

So what I found was, while variation existed; some bird perhaps not really being detectable in British context, others were quiet distinctive. Most especially in having very extensive dark flank steaking. This extended right down to the legs and then out from the flanks becoming fine dark ‘crescents’ (formed by dark feather tips), which made the ‘dark streaked zone’ really very extensive on the body sides. On some these dark crescents,while weakly marked were easy to see on scope views extending right across the white underparts. Don’t remember that in the old school of Guillemot ID!

Dark spotty underwings are well known as a feature which increases in frequency as you move from Southern through Northern to Arctic breeders:

BWP indicates that while other taxa have pre-breeding moult which ends in March, hyperborea is later (from mid-April to late May). Thus these breeding adults are in spanking fresh plumage which includes, in some, obvious dark crescentic tips to the white underpart feathers. Combined with the blackish plumages, very extensive dark flanks marks, extensive dark underwing spotting- I wonder if you could ID one in Britain? Does the post breeding (July to November) moult produce this same dark crescents and if so would they be worn of in mid winter? Do Southern (albionis) and Northern (aalge) Guillemots ever show these dark crescentic marks? Fun to ponder!

A few more shots of Arctic Guillemots:

Showing appearance on water, inc. extent of flank streaking

I notice some still moulting out of non-breeding plumage (2nd cal yrs?) nevertheless had the same extensive flanks streaking when viewed on the water. More northerly breeders more often have full dark band across the throats in winter plumage than southern birds.

One on right with more of an ‘inverted V’ where dark meets white on neck, though not as striking as on Brünnich’s Guillemots. Bird centre left with weak pale gape or ‘tomium stripe’.

And in flight, flank streaking appearance from less to more obvious (dark crescents visible on the lower one):