First-hand experiences of Caspian Gull (Larus cachinnans, Sztyeppi sirály) in Hungary
|1. Adult (close to breeding colony) at Hortobágy-fishponds, Hortobágy, Hungary; 25th April 2010|
Shape and barepart colours are of more use in the field than is plumage in adult birds:
- Slender, longish bill without noticable gonys.
- Small, "beady", darkish eye.
- Long, prominently sloping forehead - but with a gentle curve. Head profile not as strong or brutal looking as that of other gulls of similar size.
- Leg colour cannot be seen properly here, but anyway pinkish. Bareparts typically dull even in summer plumage.
Immature birds are not always separable readily from commoner Yellow-legged Gull (Larus michahellis michahellis). Barepart colouration is not much help in immature birds, and for some reason the shape differences listed above for adult birds are not so prominent either - but still valid anyway.
So, in immature birds, we have to revert to plumage marks to look. These are the following:
- Pale window of inner primaries (resembling to Herring Gull Larus argentatus of similar age)
- 'Venetian blind'-like (HU: zsalugáter-szerű) pattern on the dark inner primaries (formed by the repetition of two-toned primary feathers - distal webs being dark, inner webs paler)
- Silvery pale scapulars and mantle/back with few and simple darkish markings
|3. The same individual as in fig. 2, from above|
|4. The same individual as in fig. 2, from below|
Underwing including axilliaries is definitely pale/whitish.
|5. The same individual as in fig. 2 (with a blue colour - Hortobágy - ring)|
Bill colouration makes the gonydeal angle somewhat more discernible from this angle.
Used and recommended references:
Gibbins, C., Small, B. J., Sweeney J. 2010. From the Rarities Committee’s files: Identification of Caspian Gulls. Part I: typical birds. British Birds 103: 142-183.
Malling Olsen, K., Larsson, H. 2003. Gulls of Europe, Asia and North America. Christopher Helm, London.
Van Duivendijk, N. 2011. Advanced Bird ID Handbook: The Western Palearctic. New Holland Publishers.