Larus cachinnans in Poland

(last update: July 19, 2021)

Marcin Przymencki
Klaudia Litwiniak
Mars Muusse


Cachinnans breeding in Poland - project information

Please, put your observations of colour ringed birds to:
If you have any questions, mail to: marcin.przymencki @

Initiation of this project

Since 1999, when Caspian Gulls started breeding in Poland regularly, local ornithologists have been paying attention to this species. Years were passing and there were more and more pairs and nesting sites. Co-working within gullers was more or less coherent, but monitoring and ringing was done by many people. In the first decade of 21st century Grzegorz Neubauer and Magdalena Zagalska-Neubauer started a project in the hybrid zone between Caspian and Herring Gulls.

Their study area was a colony in Włocławek. They published many papers and did a lot for a better understanding of phenotypics of Caspian and Herring Gulls and gene flows between these two species. In the end of 2020 our forces were joined totally. We started to cooperate and work with common methodology in all Polish colonies of Caspian Gulls. We established standards of work in colonies to achieve:

  • monitoring of all nesting sites of Caspian Gulls in Poland and finding new ones
  • counting breeding pairs and follow trends
  • ringing and measuring birds in a standardised method
  • reading ringed birds in colonies
  • collecting interesting data on Caspians and other large gulls nesting in their colonies mainly on breeding biology and movements
  • and of course our main aim is to publish this.
Wloclawek Reservoir - Zalew Włocławski (52°39`N, 19°08`E). Study area for contact zone between Herring and Caspian Gull. Picture: Jan Wende, Michal Zielinski & Danidan.
Part of the largest colony of large gulls in Poland, near Zaslow Karczmiski, middle Vistula. May 2004. Picture Greg Neubauer.
Larus argentatus sensu lato 3P70 adult, May 02 2014 - April 20 2015, Zastów Karczmiski, Poland. Most likely a hybrid Herring Gull x Caspian Gull. Picture: Łukasz Bednarz ringing team.
Species structure in local large gulls populations, based on trapped birds (left side) and pair composition (right side) within the north-south gradient in Poland. HG = Herring Gull (individuals left, pairs right), CG = Caspian Gull, YLG = Yellow-legged Gull, HYB = hybrids or mixed pairs, ‘?’ = not identified individuals.