Caspian Gull Photo Essay. From first-winter to second-winter
Brian J Small
The following images, all of the same gull, were taken around the Blyth estuary, Suffolk, UK, and offer a good insight into the changing plumage features, structure and moult of this species during its second calendar-year. The text highlights the important aspects of its identification towards the end of the year.
This article is intended to augment the identification paper on Caspian Gull at this site, and anybody interested should refer to it for more detail.
First-winter Caspian Gull, Blythburgh, 10th February 2000
Southwold harbour, 18th April 2000
Blythburgh, 1st August 2000
Fig. 4
Blythburgh, 11th August 2000
Compare the above two images, taken ten days apart. Note the dropping of the outermost primary, and how different the gull looks from a new angle.
Fig. 5
Walberswick pigfields, 7th September 2000
Note the advance in plumage from August. The tertials have been dropped, the mantle & scapulars are intrinsically grey, the body is whiter and the bill is paler.
Southwold, 5th November 2000
Fig. 7
Southwold harbour 27th November 2000 (adult Herring Gull argenteus to its left)
Note the structure: relatively small, distinctively shaped head (high sloping forehead – quite domed – with a peak on the nape); long bill, a pinkish base and white tip separated by a fairly broad dark sub-terminal band; quite high chest; flat backed without a tertial step; thin and long primaries; long legs. The stance is also interesting, in that it holds the wings angled down – a more upright stance.
The plumage shows the classic features, in particular the advanced state of moult, whereby more adult-like feathers are present than is typical for Yellow-legged and Herring Gulls; the mantle and scapulars are third-generation and almost entirely grey (a flat grey, subtly darker than the Herring– in fact almost identical to Common/Mew Gull); the lesser- and inner greater-coverts are new third-generation, grey feathers – the remaining greater-coverts are second-generation (moulted during the ‘first-summer’ – a Caspian Gull has three sets of some coverts during its second-calendar-year); the tertials are new, adult-like, third-generation grey features, contrasting with the black (with white edges and tips) second-generation inner secondaries; finally, the head is very white with minimal streaking, most obvious as a shawl on the hind-neck.
Note the eye is black and looks small; the colour of the legs in comparison with the Herring Gull, is a pale pinkish grey.
Fig. 8
Southwold harbour, 27th November 2000
As well as showing the bill pattern clearly, this image is interesting in that the whole of the median coverts have been shed, leaving the bases of the greater-coverts exposed (they are largely second-generation). However, of more interest is the pattern on the underside of the longest primary: this shows a small white mark near its tip, coming from the white shaft streak. The primaries are second-generation, and to my eyes look rather narrow and pointed.