The posture Caspian Gull (Larus cachinnans) frequently adopts during its long call, with wings raised and head held vertical, has been described as diagnostic for the species (Klein & Buchheim, Limicola 17, 21-26, 2003; Gibbins, Small & Sweeney, British Birds 103, 142-183, 2010). In difficult plumages or stages of moult and wear, especially in immature birds in summer, it can be very helpful to clinch an ID.
During my recent short trip to Pusztaszer, I had the opportunity to watch dozens of immature Caspian Gulls mixed with some Yellow-legged Gulls (Larus michahellis) at a feeding place. Many Caspian Gulls (probably all males, judging from their size and „brute“ look) stood out by their aggressive behaviour, frequent fights over dead fish which were available en masse and the striking albatross posture during their rapid, laughing long call.
Not all birds were easily identified though. I will probably post some images of rather challenging birds (to me at least) later.
