Larus cachinnans

(last update: February 16, 2013)

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

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cachinnans plumages

Larus cachinnans 4P35 adult, May 06 2014, Zastów Karczmiski, Poland. Picture: Łukasz Bednarz ringing team.

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, with high bill and rich yellow legs. Probably within limits for (male) cachinnans. Adult, with dense speckling in iris. Red orbital ring and gape. Faint red on upper mandible; black on the upper and black on the lower mandible. Yellow legs.
Moderate white tongue on P10 (medial band just broader than white tip; note also diffuse transition between black and white), and broad black band on P5; no black spot on P4. P1 still present; PMS=0.