Larus cachinnans in the Netherlands

(last update: August 16, 2020)

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Caspian Gull cachinnans F|0 1CY, May 28 2021, Lelystad, the Netherlands. Picture: Albert de Jong & Mars Muusse.

Ringed as pullus Larus cachinnans on May 28 2021 at nest 60 in colony Lelystad, the Netherlands.
ID of parents from nest 60 is uncertain in 2021, and it's also not certain if this pullus b-F|0 is from that nest 60 or from an adjacent nest.

Visits and data.

date:                
24-04-2021 Probably 2 partners present, but difficult to allocate birds to the nests. Nest allows trapping breeders, but early nest!
  One partner is fierce male Caspian Gull.
  3 eggs in nest.            
  egg no: width (mm) length (mm) volume (cm3):  water test on April 24th:       
  A egg 50,2 68,3 86,66 90 - floating halfway      
  B egg 47,9 64,6 74,63 90 - floating halfway      
  C egg     no measurements due to cracks in shell  
  sum nest: --        
   
26-04-2021 Pictures taken from canoe, of several birds flying around nests 60-62-63. How to monitor, telescope?
   
13-05-2021 2 chicks of nest 60 hide underneath Angelica cover, 45 cm's from nest.
   
15-05-2021 Fish at nest: Rounded Goby 3x. Chick 2 vomited Rounded Goby (pellet taken for analysis).
    mass head+bill (measurements Monika Ballmann)    
  pullus 257 gr 68,2    
  pullus 261 gr 68,5    
                 
    metal tibia head + bill comments:
28-05-2021 pullus .5559412 b-F|0 92,3 Large pullus (16-18 days old), likely cachinnans from nest 60.
  pullus .5559413 b-F|1 95,3 Large pullus, likely cachinnans from nest 60.
  pullus .5559414 b-F|2 75,8 Possibly argentatus, not necessarily from neighbour's nest, b-F|3 broken.
  pullus .5559415 b-F|4 73,2 Possibly argentatus, not necessarily from neighbour's nest, b-F|3 broken.
  pullus .5559416 b-S|3 56,8 Likely argentatus, from neighbour's nest.
  pullus .5559417 b-S|4 57,2 Likely argentatus, from neighbour's nest.
               
08-06-2021 3 adult Caspian Gulls present. No chicks visible from canoe, not on south nor on north side from water. They probably hide in blackberries complex.