Larus cachinnans
(last update:
Greg Neubauer
Marcin Przymencki
Albert de Jong
Mars Muusse
cachinnans plumages
Larus argentatus sensu lato 4P24 adult, May 05 2014, Zastów Karczmiski, Poland. Picture: Łukasz Bednarz ringing team.
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Location: Zastów Karczmiski, Poland - colony at the banks of the Middle Vistula river.
In 2004 240 breeding pairs (95% cachinnans, <5% argentatus). (Ornis Fennica 2011 88, 80-89) and in 2012 592 pairs (90% cachinnans, <10% hybrid / argentatus) and possibly Larus michahellis (pers comm. Łukasz Bednarz).
Middle Vistule river is a location where several taxa breed: see composition. Since this is a mixed breeding population where hybridisation is not uncommon, the ringing centre in Poland decided to label birds "Larus argentatus sensu lato". Still bulk of the breeding birds in Middle Vistula region show features of cachinnans.
Breeding bird trapped at the nest, showing little similarity to argentatus (F2?) in obvious gonys, pink legs and medium sized medial band (no deep tongue on P10). All these features can be found in cachinnans as well however.
Adult, with little speckling in iris. Red orbital ring and gape. No red on upper mandible; no black on the upper and faint black on the lower mandible. Pink-fleshy legs.
Medium white tongue on P10 (black on innerweb of P10 running up all the way to primary coverts, medial band is broader than white tip, but white tongue has nice angular end as in cachinnans), broad black band on P5; no spot on P4.
P2 dropped, P1 growing, PMS=3.
