Larus cachinnans in the Netherlands

(last update: August 16, 2020)

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Caspian Gull cachinnans F|K 1CY, May - June 2021, Lelystad, the Netherlands. Picture: Jeroen Nagtegaal & Mars Muusse.

Blue bar tibia ring b[F|K], ringed as pullus Larus cachinnans on May 28 2021 at nest 38 in colony Lelystad, the Netherlands.
ID uncertain, one adult, the male, is Caspian Gull cachinnans. Female has some argenteus influences, generally considered 'a river gull' by us, a label for those birds that don't tick all the boxes.

below: Caspian Gull cachinnans F|K 1CY, June 26 2021, Lelystad, the Netherlands. Picture: Mars Muusse & Jeroen Nagtegaal.

below: Caspian Gull cachinnans F|K 1CY, May 28 2021, Lelystad, the Netherlands. Picture: Mars Muusse.

With b-F|J from the same nest, nest 38.

Data:

date:              
21-05-2020 Two pulli found, ringed b[F|G] & b[F|H]. Food: Round Goby, wrap of pork sausage. Both adults overhead alarming. Both unringed.
02-06-2020 Adult with at least one ringed pullus at location. We didn't manage to read the code.
               
16-4-2021 Nest checked. No eggs. Adult present: female cachinnans-type same as last year.
  egg no: width (mm): length (mm): volume (cm3):  water test on April 24th: laying date:  
24-4-2021 A 51,9 74,0 100,36 40 - tip bottom    
24-4-2021 B 51,9 75,4 102,26 50 - tip bottom  
24-4-2021 C 51,1 71,8 94,40 30 - tip bottom  
sum nest: 297,02
06-5-2021 Female present. 3 eggs in tact.
13-5-2021 2 partners present. Male is brutal cachinnans.  
15-5-2021 1 egg in tact.  
15-5-2021 1 egg hatching.  
15-5-2021 1 hatched chick. Mass = 75 gr.  
    metal ring darvic ring mass head + bill  
28-5-2021 pullus .5559376 b-F|J 554 85,8 Thrown up prey from chick: worms and fish.
28-5-2021 pullus .5559377 b-F|K 546 83  
           
8-6-2021 No visit.  
metal ring darvic ring mass head + bill wing  
26-6-2021 pullus .5559377 b-F|K 1174 125,5 363 retrapped chick and controlled.