Arctic Guillemot ssp. hyperborea

Still Identifiable

Hypothesis: Despite not even being recognized as a valid taxon in some quarters, some Arctic Guillemots ssp. hyperborea may be identifiable within and outside of their range (as wanderers/vagrants) by dark crescentic barring over the underparts. NGB birders report:
 

Gullfest 2014,  Zac Hinchcliffe,  Next Gen Birders

check out this fella picked out by Gullfesters yesterday:

Arctic Guillemot ssp. hyperborea, Hornøya Island, Varanger. 21 March 2014, Zac Hinchcliffe. The breeding guillemots here are of the Arctic form. Some have dark crescentic marking across the underparts which may be a character only found in this taxon. This individual takes the character it to a whole new level!

Arctic Guillemot ssp. hyperborea, Hornøya Island, Varanger. 21 March 2014, Zac Hinchcliffe. The breeding guillemots here are of the Arctic form. Some have dark crescentic marking across the underparts which may be a character only found in this taxon. This individual takes the character it to a whole new level!

 

hyperborea– Identification possible?

reblogged from 2012 – MG

I’m back on 13th May 2012 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 GuillemotsAlso 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.

3 old taxa:

Southern Guillemot (ssp albionis) 

Northern Guillemot (nominate aalge)

Arctic Guillemot (ssp hyperborea)

Very crudely  southern albionis breed in England and Wales, and nominate ‘Northern aalge breed  in Scotland. N. Ireland probably has a bit of both (mostly Northern).

Arctic Guillemot ssp hyperborea presumed to be a rare vagrant.

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. 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.

Do Southern (albionis) and Northern (aalge) Guillemots ever show these dark crescentic marks?

Some Distinctive

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.

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?

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):

 

 

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