This Caspian Gull has relative long pale and characteristic thin legs. Most often when seeing cachinnans in Denmark the thinner legs and the longer tibia compared to argentatus is quite obvious. The small eye is situated closer to the forehead than in argentatus and the colour is relative dark with a slight green peppering in the iris – most easily seen when light hits the eye directly. The eye in this cachinnans is paler than average, but certainly within their variation and when seen at some distance due to the peppering and the smaller size it stood out at being rather dark in contrast to argentatus.
There is a thin red orbital ring seen at close range. The bill is relative long and without pronounced gonys angle. It has a good cachinnans jizz with a high push up breast, flat belly slightly dropped behind legs and long slim rear with the growing p9 and p10 just adding to elongated impression this species gives.
Additionally the upperparts are slightly darker than on nearby argentatus which was obvious in both overcast and sunny weather. It is not yet in full summer plumage as it has retained some of the distinctive dark spotted neck boa in contrast to the snowy white unspotted head. The distinctive black feather shafts on the outer primaries in the upperwing is commonly seen in adult cachinnans and in the stretched wing the grey tongues on the outer primaries are obvious when seen from underneath, on p5 there is a broad black band, on p10 the outer tip is all white. The white apical spots are all relative small.
In flight the hand is slender even though p9 and p10 is not yet fully grown and when seen from the underwing the black on primaries creates a classic cachinnans boomerang. On the yawning gull the bare part colour in the opened bill is spot on cachinnans being orangey-yellow at the base of the mandibles. The skin colour is typical blood red in michahellis and light pink in argentatus.