I was without photo editing software for a while following a recent computer upgrade so I have only just been able to revisit the awful collection of ‘dot shots’ which were all I managed to get of the recent Kumlien’s Gull in Warwickshire. Below is what is probably the best of the flight shots, in which the contrast between the dark outer primaries and paler inners is just about visible.
Juv. Kumlien’s Gull Weston Landfill Warks.
Dan Watson also sent me this link http://www.tertial.us/gulls/tkg.htm to a US site which proposes a 28 point scale with the aim of developing a frame of reference for the discussion of ‘1st cycle’ thayeri/kumlieni/glaucoides (at least I think that is the aim!). I am not sure what I think about it and to be fair the author himself poses the question ‘What does the total score mean?’. His answer is that he doesn’t know but just for fun I calculated the score for the bird above (using field descriptions not the photos) and arrived at a total of 21. On this scoring system that puts it in what the author refers to as ‘the intergrade zone between kumlieni and thayeri’. If kumlieni represents a population of Thayer’s Gull x Iceland Gull hybrids then this bird would have to be a Kumlien’s Gull at the dark end of the spectrum. If kumlieni is treated as a race of Iceland Gull (or even as a stabilised species with hybrid origins) then on this scoring system the bird would fall in the hybrid zone between that form and Thayer’s Gull. I think it is very close to some of the individuals here http://birdingfrontiers.com/2014/03/05/dark-1st-cycle-kumliens-gulls/ and if Peter Adriaens is happy these are Kumlien’s Gulls then that is good enough for me.
Finally a question I have not previously posed. Could the bird be any other kind of hybrid? To answer this I pose another question, are there any anomalous features?
1. The bird was large but I wouldn’t say it was any larger than the Kumlien’s Gull which toured the Midlands early in 2009 an interesting account of which can be found here http://www.birdingtoday.co.uk/birdwatching_articles_18.html . I can remember that concerns were raised by birders in Leicestershire and Bedfordshire regarding the size of this bird.
2. The head and body plumage was dark and rather fine but I would say consistent with some of the birds here http://birdingfrontiers.com/2014/03/05/dark-1st-cycle-kumliens-gulls/ . As with all other plumage the appearance of the head and body varied with the light. Close up and in poor light on 17/01 individual white feathers were visible in the face and neck but I have one extreme long range photo taken in strong light in which the front of the lower neck appears streaked.
3. In my original description from 13/01 I refer to the median coverts as appearing paler than the rest of the upperparts, attributing this (probably incorrectly) to fading. Martin Elliott has raised concerns that in some photos the inner greater coverts appear rather uniform. I suspect that this may be another feature which was heavily influenced by light conditions but it remains the one potential serious anomaly in my opinion.
If an alternative hybrid origin were supposed then the question of parental identity would be begged. I can see no obvious features which would be readily attributable to any forms outside the glaucoides/kumlieni/thayeri complex and I will now shut up about it unless somebody relocates it.
High hopes that the ‘white-winger’ drought might relent following the gale force NW winds this week were dashed. I did the gull roost at Draycote Water every night and two 2nd W Caspian Gulls were the only good birds I could find aside from a couple of Yellow-legged Gulls.
2nd W Caspian Gull Draycote Water
I did finally get round to visiting Draycote in the day time where the European White-fronted Geese and drake Smew were still present.
European White-fronted Goose Draycote Water
Smew Draycote Water