Gull sp? Poolsbrook 17/2/07

On Saturday 17th February 2007 I visited Poolsbrook CP to look for Gulls. On arrival I scanned through the flock looking to see if any of the white-winged Gulls that have been around were present. None were but a dark Herring Gull type immediately caught my eye. This bird was striking due to a dark area formed by the tertials inner greater coverts and median and lesser coverts. As the bird turned to face away from me I was struck by the rather dark heavily marked undertail coverts and what appeared to be a completely dark tail. By now I was beginning to think of the possibility that it could perhaps be a smithsonianus but a few seconds later, before I could get my camera out, it flew off towards Barrow Hill Tip. In flight I felt sure it had a completely dark tail though I only saw the upperside very briefly and it seemed that any chance of identifying it had gone. Over the next couple of hours a first-winter Iceland Gull came and went and I was joined by Adam Sas. Eventually a large group of Gulls arrived from the Barrow Hill direction and I immediately picked this bird out in flight from its tail pattern and was able to get the photos below when it landed. Although not a full description I hope below to outline some of the differences this bird showed from nearby Herring Gulls.

                              1                              2                               3

Apart from the distinctive tail pattern the bird differed from all the other Herrings present in numerous other respects. In picture no 1 note the dark centred tertials with a narrow fringe at the tip, only extending about halfway towards the base. Also the tertials are very worn and note one is missing on this side. The inner greater coverts appeared very plain dark brown with very faint notching visible on the lower edges quite unlike the heavily barred feathers on all the other 2nd cal yr Herrings present. The rest of the greater coverts appeared as a rather faded pale area of mottled white and brown quite unlike the much more heavily barred appearance of nearby Herrings. The median and lesser coverts were a rather faded plain chocolate brown with narrow buffish fringes reminding me of a juvenile Lesser Black-back or Yellow-legged Gull and lacked the more chequered dark brown and whitish appearance of all the other Herrings present. The scapulars were also strikingly different from the other Herrings present having paler less blackish internal barring. This internal barring consisted of 3 weak cross bars not reaching the edges the terminal one more arrowhead shaped in some and more anchor shaped in others. Some upper scapulars also differed in having three rounded lobes forming a rather oak leaf like pattern. In comparison the Herrings present all had more prominent darker barring, though undoubtedly some will show weaker barring. A few juvenile lower scapulars remained, just visible below the other scapulars. These appeared to be very worn and faded, with plain dark brown centres and a buffish fringe. 

                              4                             5                                 6

In photo 4 compare with the 1stW Herring to its left. Note the differences in the tertial fringe, scapular and covert patterns. This shot also gives some idea of the bulk of the bird, it was larger than many, but not all other Herrings present with a fairly hefty bill. The bill appeared mainly dark but when viewed in better light had a dark tip, cutting edges and culmen. The lower mandible had a barely noticeable paler base while the upper mandible had a fairly extensive greyish-flesh base (photo 1). Several structural differences were apparent, the body seemed fuller and did not seem to dip as much towards the tertials as on the Herrings alongside and the tertials formed a chunkier slightly more square patch rather than the rather more wedge shaped patch of nearby Herring. This seemed to be due partly to there being less difference between the length of the longest and the shortest tertials. 

                             7                               8                                  9

The nape had quite heavy streaking which was not too obvious at rest with the neck withdrawn, but very obvious when more alert with the neck stretched as in photos 7 & 9. At one point another Herring Gull grabbed it by the tail, and in the commotion that followed I had quite good views of the uppertail. I was not quick enough to photograph this but did get a reasonable picture of the underwing (photo 8) as it reared up and spun around to face its attacker. I thought the underwing appeared very similar to this bird here. Shortly after this the bird preened briefly and flapped its wings a couple of times. Again I failed to get a photo of the uppertail, but did manage to capture an image showing the lower back and part of the rather dark barred rump (photo 9). Shortly after this it flew off and I attempted to get a flight shot but unfortunately still only managed to capture the underside of the tail (photo 10). 

                           10                                 11                             12

Photos 11 & 12 shows an enlarged view of the undertail coverts and undertail. This area generally appeared much darker than any of the other Herrings present. The undertail coverts were heavily barred becoming darker towards the tips forming a solidly dark area only broken by whitish spots. The tail appeared completely blackish brown on both surfaces with no white visible at the base. The outermost rectrices had very small white markings on the outer edge. At times these appeared as 3 white beads, though a narrow white line along the outer edge appeared to almost join the inner 2.

Due to a lack of time I have not had chance to research properly yet, and so far have not found any photos that match this bird in appearance, but I present these photos here in hope of some early reaction while the bird may be still present in the area. Although not one of the classic obvious examples, some of the features point to the possibility of it being a smithsonianus but could it be something else? I would welcome any comments on the identity of this bird.

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