Larus cachinnans

(last update: February 16, 2013)

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

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cachinnans plumages

Larus argentatus sensu lato 4P08 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 argentatus influences but also some cachinnans influences. Breeding bird trapped at the nest. Adult with powerful bill, pale orange orbital ring and relatively broad medial band.

Very little speckling in the yellow iris. Pale orange orbital ring and gape. Faint red on upper mandible; no black mark on the bill. Saturated yellow legs.
Medium pale tongue on P10 with black on innerweb reaching primary coverts, broad band on P5; no black spot on P4. P1 growing, PMS=2.