This was one of a number of posts I deleted earlier in the year to create space on the site but have I recreated it in light of the continued discussion regarding the bird currently present in Swanhurst Park, which is considered to be the same individual returning. It was originally suggested this bird may be a Caspian Gull. The counter arguments, summarised in this post, I think, pretty much put paid to that diagnosis but it was subsequently suggested that it may be a Yellow-legged Gull x Caspian Gull hybrid. I was of the opinion that there was nothing anomalous about it and thus no need to invoke a hybrid hypothesis. I have to confess that if the bird currently present is the same individual, then the grey tone does look a little pale in some photos but this may result from camera settings and light conditions when the photos were taken. In one set of images the grey tone appears darker in one shot than it does in the other two. I have yet to go back and see it for myself but here is the post from February.

As is often the case when one good bird is found, the resultant twitch yields another. In this instance it was a 1st W large gull which divided opinion between Caspian and Yellow-legged Gull. I discuss the bird here simply because the site offers the opportunity but recognise that most of the points raised have been made by other observers (including Donna Mallon and Dave Hutton who have kindly allowed me to use their images). The bird was a 1st W but had begun its moult in to 1st S, which is essentially the start of the progression to 2nd W plumage. This is evidenced by the replaced inner greater primary coverts which are well illustrated in the photo below. I have reproduced this shot, despite its poor quality, as it is the only one I have available to illustrate the upper tail. The solid black tail band was narrower than that often shown by Caspian Gull, had a neat, clean cut upper border lacking the vermiculations above it that are frequently shown by that species and the white outer web to the outermost tail feather was unbarred which is typical of Yellow-legged Gull. The heavy dark markings in the upper tail coverts may be within the range of variation for Caspian Gull (I am unsure) but would be unusual so late in the season, and were heavier than those exhibited by many Yellow-legged Gulls.

1st W Yellow-legged Gull, Sutton Park. 

This photo of a Juv. Yellow-legged Gull illustrates the typical tail pattern though the tail band is a little fuller and the outermost tail feather shows even more extensive white than that of the Swanhurst bird whilst the uppertail coverts are more sparsely marked.

Juv. Yellow-legged Gull, Draycote Water. Photo by Dave Hutton. 

The solid, dense, barred markings on the undertail coverts are particularly well illustrated in the next photo. These are again typical for Yellow-legged Gull but would be at the least unusual for Caspian Gull which generally has neat arrowhead markings. The retained greater coverts showed distinct transverse bars which are typical of Yellow-legged Gull and would again be, at the very least unusual, for Caspian Gull. Many of the second generation scapulars had broad dark transverse bars in the centres typical of Yellow-legged Gull. Those of Caspian Gull would generally be grey with narrow dark shaft streaks and sub-terminal spots or narrow anchor markings.

1st W Yellow-legged Gull, Sutton Park. Photo by Donna Mallon. 

Extensive brown feathering on the head and body is also evident here and would again be unusual in a Caspian Gull so late in the season. Classically, Caspian Gull will show fairly clean head and body plumage with a neat shawl of dark streaks at the base of the neck by this time of year. Though the extent of brown on the underwing coverts was within the range of variation shown by both species it would more likely be shown by Yellow-legged Gull in mid February.

1st W Yellow-legged Gull, Sutton Park. Photo by Donna Mallon. 

Whilst the bill may or may not have been within the range of variation shown by Caspian Gull (I am unsure) it certainly lacked the classically described profile of being long and parallel sided and whereas it was somewhat narrow compared to that of many Yellow-legged Gulls the profile was typical of that species with a distinctly hooked pale tip and a lower mandible which narrowed before the gonys resulting in a fairly sharp gonyedal angle. This photo of a 2nd W Yellow-legged Gull illustrates the bill profile in question.

2nd W Yellow-legged Gull, Draycote Water. 

The Swanhurst bird did have comparatively long legs but as the previous photo illustrates they are again typical of Yellow-legged Gull.

1st W Yellow-legged Gull, Sutton Park. Photo by John Judge.