Albert de Jong
Larus argentatus sensu lato 3P01 adult, April 15 2014, Zastów Karczmiski, Poland. Picture: Łukasz Bednarz ringing team.
Location: Zastów Karczmiski, Poland - colony at the banks of the Middle Vistula river.
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. Adult, with almost thayeri pattern on P10. Deep tongue on P10 and full band on P5. Small dark marking on P4. This probably is adult cachinnans.