Dutch Birding volume 31 (2009) no 5

Mew Gull showing characteristics of Kamtchatka Gull at Egmond aan Zee in February 2005

On 12 February 2005, a first-winter Mew Gull Larus canus showing characteristics strongly indicative of Kamtchatka Gull L c kamtschatschensis was seen and video-taped by a single observer on the beach of Egmond aan Zee, Noord-Holland, the Netherlands. The characteristics pointing towards kamtschatschensis were, compared with Common Gull L c canus and Russian Common Gull L c heinei: 1 the bulky appearance (like a Ring-billed Gull L delawarensis or a small Herring Gull L argentatus); 2 the squarer head; 3 the stronger pinkish bill with contrasting well-marked black tip; 4 the broader black tail-band and washed-out markings on the edges of the tail; 5 the undertail-coverts with extensive dark V-markings; 6 the rump and tail with dark spots and bars; and 7 the underwing-coverts with broader dark tips and axillaries, creating a dark underwing. Some of these characteristics or a combination can also be shown by some nominate canus or heinei. Examples of such birds observed in western Europe in recent years are discussed and illustrated for comparison and discussion.
The observation at Egmond was submitted to the Dutch rarities committee (CDNA). Although the CDNA confirmed that the characters of the bird pointed strongly to kamschatschensis and probably excluded even a well-marked heinei, current knowledge was regarded as insufficient to accept it as the first kamschatschensis for the Netherlands and the WP. The differences with heinei and the variation within heinei are not yet fully understood and the occurrence of kamtschatschensis in the WP is not yet proven and would therefore require a fail-safe identification (eg, a bird in the hand or a ringed bird). The occurrence of 'look-alike' Common Gulls (both in nominate canus as in heinei) showing one or more characters considered indicative of kamtschatschensis in several western European countries (eg, Belgium, Britain, Germany and the Netherlands) indicates that it may be very difficult to prove the occurrence of an undisputed kamtschatschensis based on field documentation alone. The recent occurrences of Pacific gull species as vagrant in the WP (notably Glaucous-winged Gull L glaucescens and Slaty-backed Gull L schistisagus) show that genuine vagrancy of kamtschatschensis should not be dismissed.

Leon Edelaar, Guyotte van IJsselsteinlaan 32, 1934 GN Egmond aan den Hoef, Nederland
(l.edelaarquicknet.nl)
Enno B Ebels, Joseph Haydnlaan 4, 3533 AE Utrecht, Nederland
(ebelswxs.nl)