| Coordinator: Albert de Jong
 Merijn Loeve
 Roland-Jan Buijs
 Thijs Horst
 Leon Kelder
 Mars Muusse
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 Nests at De Kreupel 2020nest  r-02P4 20
 nest y-X804 20
 nest D01 20
 nest D02 20
 nest D03 20
 nest L01 20
 nest L02 20
 nest L03 20
 nest M02 20
 Nests at De Kreupel 2021nest  r-02P4 20
 nest w-201U 21
 nest g-XLHD 21
 nest r-KA 21
 nest r-KB 21
 nest r-KC 21
 nest r-KD 21
 nest r-KE 21
 nest r-KF 21
 nest r-KH 21
 nest r-KJ 21
 nest r-KK 21
 nest A01 21
 nest C03 21
 nest C04 21
 nest C06 21
 nest D01 21
 nest D03 21
 nest D05 21
 nest D06 21
 nest D07 21
 nest D08 21
 nest E01 21
 nest H01 21
 nest L01 21
 nest L02 21
 nest L05 21
 nest L06 21
 nest L07 21
 nest M01 21
 nest M04 21
 nest M06 21
 nest Q01 21
 |  Caspian Gull cachinnans FM 1CY-2CY, May  2021 & July 2022, De Kreupel  & Almere, the Netherlands. Picture: Leon Kelder & Eric Roeland.Tibia  P-FM and metal Arnhem 5.556.709, ringed as pullus Larus cachinnans on May 14 2021 at  IJsselmeer (De Kreupel), Holland (5247.00 N 513.00 E) - ringer  Leon Kelder.Pullus at nest C04 21 in colony De Kreupel island C, the Netherlands. ID  uncertain:       parents are unknown.
 Recoveries:04-07-2022 Almere (De Vaart), Flevoland, NL 5.224,00 N 514,00 E colourring read Eric Roeland
 Data for  nest C04-2021:       
        
        
        
        
        
        
        
        
        
        
        
          | Date: | details: |  |  |  |  |  |  
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          | 23-4-2021 | 2 eggs in nest. | egg no: | width (mm): | length (mm): | volume (cm3): |  |  
          |  |  | A egg | 52.0 | 71.3 |  |  |  
          |  |  | B egg | 51.3 | 74.5 |  |  |  
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          |  | Attempt to trap adult at nest. Failed. |  |  |  |  |  |  
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          | 14-5-2021 | 2 chicks in nest. | metal: | tibia: | mass (gr): | head + bill: | tarsus: |  
          |  | https://waarneming.nl/observation/214661957/ | NLA 5.556.708 | Pale FL | 74 | 50.5 | 29.1 |  
          |  |  | NLA 5.556.709 | Pale FM | 78 | 53.4 | 27.7 |  
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          | 20-5-2021 | Empty  nest. |  |  |  |  |  |  
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          |  |  |  |  |  |  |  |  below: Caspian Gull cachinnans FM 2CY, July 04 2022, Almere,  the Netherlands. Picture: Eric Roeland.
 
 below: Caspian Gull cachinnans FM 1CY, May 14 2021, De Kreupel  - C, the Netherlands. Picture: Leon Kelder. 
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