Larus cachinnans

(last update: February 16, 2013)

Coordinator:
Peter Adriaens (Belgium)
Ies Meulmeester (Netherlands)

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cachinnans plumages

Larus argentatus sensu lato 4P10 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.

Probably some cachinnans influences, but also some michahellis influences? Breeding bird trapped at the nest. Adult with powerful bill and relatively broad medial band.

Dense speckling in the iris. Red orbital ring and gape. No red on upper mandible; black on the upper and on the lower mandible. Saturated yellow legs.
Medium pale tongue on P10, no mirror om P9, broad band on P5; no black spot on P4. P1-P2 dropped, PMS=2.