Caspian Gull

The Caspian Gull, previously a subspecies of G. leucophea L. michahellis cachinnans, has become a distinct species, a monotypic Larus cachinnans species. It forms with the former, but also with the G. argenté, with which it is known to hybridize in Poland, a group of large closely related gulls, with the identification problems that entail.
The Caspian Gull has a particular silhouette which comes into play in identification. It stands tall, with a strong chest, a fairly long neck and a rather small head. This head has a receding forehead, a small eye and a medium beak with parallel edges and not much of a gonys. It is preferable to have a good knowledge of large gulls in order to take full advantage of these criteria.
The adult breeding Caspian Gull has the gray on the upper surface almost identical to that of G. argenté argenteus, thus lighter than that of leucophea. Its legs are of an indeterminate color, reddish or yellowish (more yellow in leucophea, and more pink in argenté). Its little eye appears dark from afar, but this is an impression as the iris is pretty light, though not always easy to make out. In flight, one must observe the underside. The black is quite limited, though it affects the last six primary remiges (P5 to P10). yet this terminal black extends in tongues towards the base of the underside, hence the venetian blind effect mentioned in the specialized literature. Furthermore, P10 is usually pure white at the extremity (see the photos in the gallery). The sexes are similar, except for size, males being bigger than females.
The first-winter bird, such as one finds it in Western Europe during the wintertime, looks a lot like a young leucophea, but there are still remarkable differences. Morphological criteria still apply. The bird seen in profile appears tricolor, white at the head (with just a small shade before the eye), on the fore-neck and on all the lower parts, with just some grayish-brown markings on the sides and undertail, gray on the upper body with brownish-black arrow-shaped designs, and medium brown on coverts and tertiaries with definite pale fringes on the feathers.Young Caspian Gulls can be distinguished by their black wingtip and tail tip. The back and sides of the neck are finely speckled with gray-brown, forming what is known as the shawl of the young Caspian. The bill is black with a tinge of pink at the two-thirds proximal. The legs are pink.
The Caspian Gull will become an adult in its third year of civil life. The intermediate immatures plumages are not obvious and a source of confusion, but the criteria mentioned above remain useful, among others the morphology and tone of the gray on top.