| Coordinator: Albert de Jong
 Merijn Loeve
 Roland-Jan Buijs
 Thijs Horst
 Leon Kelder
 Mars Muusse
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 |  Caspian Gull cachinnans FW 1CY-5CY,   2021-2025, the Netherlands. Picture: Leon Kelder, Mars Muusse & Thijs Horst. Pale blue   tibia  ring p[FW] and metal NLA 5.556.718, ringed as pullus on May 14 2021 at nest D02 21 in colony De Kreupel island D, the Netherlands. Ringer: Leon Kelder.ID  uncertain: 1 parent is Caspian  Gull cachinnans, other parent is unknown.
 Recoveries:20-05-2021 IJsselmeer (De Kreupel), Noord-Holland, NL 5.247,00 N 513,00 E captured by ringer Leon Kelder
 11-07-2024 IJsselmeer (De Kreupel), Noord-Holland, NL 5.247,00 N 513,00 E colourring read Leon Kelder
 28-07-2024 IJsselmeer (De Kreupel), Noord-Holland, NL 5.247,00 N 513,00 E colourring read T. Horst & M. Muusse
 30-07-2024 IJsselmeer (De Kreupel), Noord-Holland, NL 5.247,00 N 513,00 E colourring read J. van Assema & T. Horst
 05-08-2024 IJsselmeer (De Kreupel), Noord-Holland, NL 5.247,00 N 513,00 E colourring read T. Horst, M. Muusse & T. Muusse
 08-04-2025 IJsselmeer (De Kreupel), Noord-Holland, NL 5.247,00 N 513,00 E colourring read T. Horst & M. Muusse
 10-04-2025 Almere (De Vaart), Flevoland, NL 5.224,00 N 514,00 E colourring read Thijs Horst
 Data for 2021: 
        
        
        
        
        
        
        
        
        
        
        
          | Date: | details: |  |  |  |  |  |  |  
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          | 9-4-2021 | 1 egg in nest. | egg no: | width (mm): | length (mm): | volume (cm3): |  |  |  
          |  | https://waarneming.nl/observation/210431375/ | A egg | 51.2 | 73.5 |  |  |  |  
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          | 23-4-2021 | 3 eggs in nest. | egg no: | width (mm): | length (mm): | volume (cm3): |  |  |  
          |  |  | A egg | 51.3 | 73.7 |  |  |  |  
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          |  |  | B egg | 50.8 | 74.4 |  |  |  |  
          |  |  | C egg | 49.1 | 71.1 |  |  |  |  
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          |  |  | metal: | tibia: | wing: | head + bill: | bill: |  |  
          |  | Adult  trapped at nest:  Caspian  Gull. | NLA 6.211.441 | Red-K.F | 484.0 | 138.3 | 67.3 |  |  
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          |  |  | mass: | tarsus: | moult score: | bill height: | grey scale | Swob |  
          |  |  | 1095 | 74.5 | 10x0 | 20.0 | 6.5 | 1082 |  
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          | 14-5-2021 | 3 chicks in nest. | metal: | tibia: | mass (gr): | head + bill: | tarsus: |  |  
          |  | https://waarneming.nl/observation/214662455/ | NLA 5.556.716 | Pale FU | 126 | 57.4 | 33.1 |  |  
          |  |  | NLA 5.556.717 | Pale FV | 185 | 63.5 | 38.6 |  |  
          |  |  | NLA 5.556.718 | Pale FW | 174 | 62.7 | 37.9 |  |  
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          | 20-5-2021 | 3 chicks in nest. | metal: | tibia: | mass (gr): | head + bill: | wing: |  |  
          |  |  | NLA 5.556.716 | Pale FU | 335 | 73.5 | 65.5 |  |  
          |  |  | NLA 5.556.717 | Pale FV | 466 | 81.8 | 77.0 |  |  
          |  |  | NLA 5.556.718 | Pale FW | 430 | 79.8 | 78.5 |  |  
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          |  |  |  |  |  |  |  |  |  below: Caspian Gull cachinnans FW 5CY,  April 08 2025, colony De Kreupel, the Netherlands. Picture: Thijs Horst & Mars Muusse..JPG)
 
 
 below: Caspian Gull cachinnans FW 4CY,  August 05 2024,   colony De Kreupel, the Netherlands.  Picture: Thijs Horst.
 
  below: Caspian Gull cachinnans FW 4CY,  July 28 2024, colony De Kreupel, the Netherlands. Picture: Thijs Horst & Mars Muusse.
 
 below: Caspian Gull cachinnans FW 1CY, May 14 2021, De Kreupel  - D, the Netherlands. Picture: Leon Kelder. 
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