Peter Adriaens (Belgium)
Ies Meulmeester (Netherlands)
Larus argentatus sensu lato 3P37 adult, April 25 2014, Wytyckie Lake - Urszulin, Poland. Picture: Łukasz Bednarz ringing team.
For 2012, breeding location of 150 pairs cachinnans, of which 54 adults ringed and 158 pulli in 2012 (pers comm. Łukasz Bednarz).
Taxa other than cachinnans are rare in this east Polish population, still mixed breeding can be suspected with migration of birds from the middle Vistula; and hybridisation may take place at very low level. Therefore the ringing centre in Poland decided to label such birds "Larus argentatus sensu lato". Still bulk of the breeding birds in Urszulin region show features of cachinnans.
Breeding bird trapped at the nest. Adult, with medium grey tongue on P10, and full broad band on P5; black spot on P4. Moderate speckling in iris. Red orbital ring and gape. No red on upper mandible (gonys spot hardly reaching to cutting edge); faint black on both mandibles; obvious gonys angle. Pink-fleshy legs with yellowish hue. This bird might be an extreme in pure cachinnans, showing much black in the wingtip, or maybe has inherited some genetics from argentatus; probably best labeled 'not further determined'.