Larus cachinnans in the Netherlands

(last update: August 16, 2020)

Coordinator:
Albert de Jong
Merijn Loeve
Roland-Jan Buijs
Thijs Horst
Leon Kelder
Mars Muusse

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hybrid ? Caspian Gull cachinnans x Herring Gull argenteus K.7 1CY, May & October 2021, De Kreupel & Almere, the Netherlands. Picture: Leon Kelder & Eric Roeland.

Red tibia ring r[K.7], ringed as pullus Larus argentatus on May 14 2021 at nest KC 21 in colony De Kreupel, the Netherlands.
ID is uncertain: mother is r-K.C Herring Gull argentatus, and father is unknown. Pictures of 1CY October chick r-F.7 suggest father to be Caspian Gull or Caspian hybrid.

below: (hybrid ? Caspian Gull cachinnans x) Herring Gull argenteus K.7 1CY, October 16 2021, Almere, the Netherlands. Picture: Eric Roeland.

below: Herring Gull argentatus K.7 1CY, May 14 2021, De Kreupel - M, the Netherlands. Picture: Leon Kelder.

Date: details:          
23-4-2021 3 eggs in nest. egg no: width (mm): length (mm): volume (cm3): 
  C egg 49.0 73.1
  A egg 48.9 70.3
B egg 49.7 73.9    
           
Attempt to trap breeding adult. Adult trapped. metal: tibia: wing: head + bill: bill:
Adult female Herring Gull argentatus. NLA 6.211.438 Red-K.C 427 119.4 51.8
  mass: moult score: bill height: grey scale: Tarsus: & Swob:
  -- left P1 missing 18.9 3.5 65.0 & 1079
           
14-5-2021 1 chick & 1 egg in nest. metal: tibia: mass (gr): head + bill: tarsus:
https://waarneming.nl/observation/214664184/ NLA 5.556.741 r-K.7 68 48.6 28.3
           
           
20-5-2021 2 chicks in nest. metal: tibia: mass (gr): head + bill: tarsus:
https://waarneming.nl/observation/214711054/ NLA 5.556.741 r-K.7 200 64.5 --
  NLA 5.556.763 -- 91 54.2 32.2