Kumlien's Gull - 1998 - first for Pembrokeshire

Larus glaucoides glaucoides

At about 16:30 on 1st February 1998, for the first time of the year, I found myself checking the gull roost at Llys y Fran Reservoir, after (yet another) fruitless search for lesser spotted woodpecker in the woodland at the northern end of the reseroir.  A number of gulls, mostly adult lesser black-backed gulls Larus fuscus or the race graelsii, were already on the reservoir.  Fairly quickly I located a 1st winter glaucous gull Larus hyperboreus amongst them and soon afterwards another 1st winter "white-winged" gull.  From its size and structure it was obviously an Iceland Gull Larus glaucoides, but some features were not consistent with a nominate race bird (the race we normally see in Pembrokeshire).

I was in no doubt that I was watching an Iceland gull, with glaucous, herring Larus argentatus and Lesser black-backed gulls present close by or next to the bird for comparison, but the bird was unusually dark for this species.  At rest the exposed primaries were pale brown with whitish fringes, not the usual white of a nominate glaucoides.  The tail was seen twice when bathing and had a distinct darker band.  On the open wing, the outer 3 or f primaries were marked with pale brown on the outer web (which was obviously the brown markings I could see on the primaries at rest).

I left the reservoir at 17:00 (when the gates closed), having watched the bird for about 20 minutes.  After reference to literature at home that evening, I felt fairly sure that the bird was a Kumlien's gull Larus glacudoides kumlieni, so I telephoned several local birders to alert them to this possibility.  A telephone conversation later that evening with Graham Walbridge, a member of the British Birds Rarities Committee (BBRC) convinced me that this was so.  The news was released onto national and regional 'birdlines' that evening.

The following evening I was joined at the reservoir by Stuart Devonald and two other local birders, where we soon located the bird.  We were able to confirm the features I had noted the previous evening and fortunate also to find an adult ring-billed gull Larus delawarensis amongst the other gulls.  On the 3 Feb the bird was also seen by others, including Jon Green and Jack Donovan, and again on 5 Feb when a number of observers saw it.  All agreed with my identification.  Just to prove that regular coverage of a site usually brings rewards, an Iceland gull was discovered on the 3 Feb, which I also saw on the 4th.  This enabled a good camparison with the Kumlien's gull (although I failed to see them both at the same time), which helped support the identification.  The Kumlien's gull was not seen after 5 Feb, despite regular watching of the gull roost.

Detailed description:

Size/structure: Overall, the bird was essentially as nominate Iceland gull Larus glaucoides glaucoides, ie similar to lesser black-backed gull in size, fairly lightly built for a 'large' gull and with delicate features.  The only structural difference to glaucoides that I noticed was the slightly shorter primary projection, which was only noticeable at rest, but this shorter winged impression could not be confirmed as no 'proper' flight views were ever obtained of the bird.  In overall size it was difficult to differentiate from an 'average' lesser black-backed gull, with which it was usually directly comparable.

Bare parts: The leg colour was not seen well, but was a shade of pink.  The bill was quite slim and small, no different from a glaucoides Iceland Gull.  It was largely black with a very small paler purplish area at the extreme base, largely on the lower mandibile, but this was often not visible.  The eye was dark.

Wings: Most views of the wings were at rest, ie just the exposed primaries.  The open wing was seen just a handful of times by me on the two occasions that I saw the bird.  At rest, the primaries were pale brown in the centre, with a neat whitish fringe, which appeared as a series of 'hooks'.  Four primaries could be see beyond the longest tertial at rest.  The longest primaries extended beyond the tail at rest but, to my eyes, not as far as most Iceland gulls I have seen, but obviously longer than Gaucous Gull.  On the few times that I saw the open wing as the bird bathed, the outer primaries had an obviously darker mark on the outer web.

Head: Creamy brown (but darker than the glaucoides present on 4 Feb), with a darker shadow around the eye, especially above it.

Upperparts: Same base colour as the head, but mottled with fairly heavy regular dark bars.

Underparts: Pale milky brown (but darker than the glaucoides present on 4 Feb), with obvious large darkish brown bars on the undertail coverts.

Tail and rump: Only seen on a couple of occasions as the bird bathed.  Rump same as mantle but more coarsely barred.  Tail had an obvious band - appeared quite even but broken towards the tip.

Overall plumage: When compared to the glaucoides on 4 Feb, which I would describe as a fairly typical individual, the overall plumage tone of the Kumlien's gull was a colder, grey brown colour, lacking the ghostly feel a glaucoides Iceland gull has.

Epilogue

This was exciting period of Llys-y-fran reservoir, with several new records.  A 1st winter glaucous gull roosting dialy from 1 Feb to 4 Mar (with a second bird from 5 to 6 Feb); an adult ring-billed gull on five dates from 2 - 8 Feb; a 1st winter Iceland gull on 3 and 4 Feb; and an adult Mediterranean gull Larus melanocephalus on 5 Feb.  Now we all know where to go when other popular gull roosts aren't producing unusual gulls, or even as a first choice!

Kumlien's gull breeds in north-east Canada and winters there and in coastal eastern North America.  It is a vagrant to Europe.  Most records occur when there are also higher than usual numbers of nominate glaucoides.  At the end of 1998, the subspecies was removed from the list of birds considered by BBRC for the following reasons:

The BBRC feels that there are a number of problems with this form.

• since the recent interest in the identification of the subspecies, it seems that Kumlien's gull is best considered a scarce winter visitor.
• the range of plumage variation is such that it is difficult to establish clear divisions between nominate Iceland gull, particularly in first-year plumages
• whilst a number can be safely identified, this is not true for many, as we know that birds indistinguishable in the field from the nominate race both breed and winter in areas where Kumlien's gull is 'meant' to occur.  In Britain we are therefore limiting ourselves to identifying only a proportion of the extra-limital visitors
• because of the problems of identification, the lack of clarity as to which birds are Kumliens', the shifting nature of its taxonomic status in Britain, which may represent a change of occurrence but is more likely to reflect a change in observer behaviour, we feel that the process of record assessment is not achieving anything scientifically.

This should not put us off looking for Kumlien's gull - 'classic' birds are still identifiable (especially adults), but some birds will have to be left as only possibly this form.  This record has been accepted by the BBRC so should give other observers an idea of what to look for in a first winter bird, to be certain of a Kumlien's gull.  With some concentrated offort, we shouldn't have to wait too long for our next record and the first of an adult bird.

For futher reading, see Gulls by P J Grant, and the article 'Plumage Variation in Kumleins' Iceland gull' by Kevin J Zimmer, pubihsed in Birding, October 1991.

David Astins

Pembrokeshire Bird Report 1998