| Coordinator: Albert de Jong
 Merijn Loeve
 Roland-Jan Buijs
 Thijs Horst
 Leon Kelder
 Mars Muusse
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 |  Caspian Gull cachinnans K.S  1CY-5CY,   2021-2025, De Kreupel  & Vlissingen, the Netherlands. Picture: Fred Visscher, Leon Kelder & Sander Lilipaly. Red  tibia  ring r[K.S] and metal NLA 5.556.724, ringed as pullus Larus cachinnans on May 14 2021 at nest D05 in colony De Kreupel, the Netherlands. Ringer: Leon Kelder.Both parents are unknown.
 Recoveries:08-01-2022 Vlissingen (Binnenhaven), Zeeland, NL 5.127,00 N 336,00 E colourring read Sander Lilipaly
 27-03-2023 Onderdijk (Vooroever), Noord-Holland, NL 5.244,00 N 508,00 E colourring read Leon Kelder
 20-04-2023 Twisk (Oostermare), Noord-Holland, NL 5.245,00 N 503,00 E colourring read Fred Visscher
 08-12-2023 Almere (De Vaart), Flevoland, NL 5.224,00 N 514,00 E colourring read Eric Roeland
 03-03-2024 Almere (De Vaart), Flevoland, NL 5.224,00 N 514,00 E colourring read Eric Roeland
 17-05-2024 IJsselmeer (De Kreupel), Noord-Holland, NL 5.247,00 N 513,00 E colourring read Leon Kelder
 13-07-2025 IJsselmeer (De Kreupel), Noord-Holland, NL 5.247,00 N 513,00 E colourring read T. Horst, M. Muusse & N. Colpaert
 below: Caspian Gull cachinnans  K.S 5CY,  July 13 2025, colony De Kreupel, the Netherlands. Picture: Thijs Horst & Mars Muusse..JPG)
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 below: Caspian Gull cachinnans K.S 3CY, April 20 2023, Twisk, the Netherlands. Picture: Fred Visscher. 
 below: Caspian Gull cachinnans K.S 2CY, January 08 2022, Vlissingen, the Netherlands. Picture: Sander Lilipaly. 
 below: Caspian Gull cachinnans K.S 1CY, May 14 2021, De Kreupel  - D, the Netherlands. Picture: Leon Kelder.       
 
        
        
        
        
        
        
        
        
        
        
        
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          | 23-4-2021 | 3 eggs in nest. | egg no: | width (mm): | length (mm): | volume (cm3): |  |  |  
          |  |  | A egg | 50.0 | 72.2 |  |  |  |  
          |  |  | B egg | 50.9 | 68.9 |  |  |  |  
          |  |  | C egg | 50.4 | 69.4 |  |  |  |  
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          |  | Attempt to trap adult  at nest. Failed. |  |  |  |  |  |  |  
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          | 14-5-2021 | 3 chicks in nest. | metal: | tibia: | mass (gr): | head + bill: | tarsus: |  |  
          |  | https://waarneming.nl/observation/214662787/ | 5556722 | Red K.P | 114 | 56.7 | 31.6 |  |  
          |  |  | 5556723 | Red K.R | 166 | 61.1 | 36.1 |  |  
          |  |  | 5556724 | Red K.S | 152 | 61.0 | 36.5 |  |  
          | 20-5-2021 | Empty nest. |  |  |  |  |  |  |  
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