Larus cachinnans

(last update: February 16, 2013)

Peter Adriaens (Belgium)
Ies Meulmeester (Netherlands)


cachinnans plumages

Larus argentatus sensu lato 3P26 adult, April 22 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.

Here, all feature point to adult Yellow-legged Gull michahellis. Breeding bird trapped at the nest. Adult, with yellow legs, much black in wingtip, small mirror on P9, short pale tongue on P10 not ending square, much black on innerweb of P8, full broad band on P5 and also black on P4 and P3, red gape, red orbital ring, heavy bill with obvious gonys and red bleeding up onto the upper mandible.