Larus cachinnans in the Netherlands

(last update: August 16, 2020)

Coordinator:
Albert de Jong
Merijn Loeve
Roland-Jan Buijs
Leon Kelder
Mars Muusse

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Cachinnans - nest Lelystad 060

General remarks:

  • Eggs: Volume measured by Stonehouse (1964) and Spaans & Spaans (1975), which make comparison possible with data from Texel (Camphuysen pers comm 16.04.2020).
  • Location marked with code "60" on tarmac dam.
  • Nest 060 on breakwater dam 1 south section, just on north side, near the top. Easy to trap the adults here.
  • Cluster of 5 nests within 10 meters range: 3x cachinnans and 2x argentatus, which are extremely difficult to monitor. Next to Angelica is nest 60, next to blackberries complex are nest 62 & nest 63.
  • ID for nest 060 uncertain in 2021, male is probably Caspian Gull cachinnans.
location April 24th, 2021: cluster of nests. April 24th, 2021: red spray "60". May 13th, 2021: Angelica nest 60.
 
eggs April 24th, 2021: 3 eggs in nest. . .
     
partner 1 May 13th, 2021: adult male cachinnans. May 13th, 2021: adult male cachinnans. May 13th, 2021: adult male cachinnans.
 
partner 1 May 13th, 2021: adult male cachinnans chasing neighbour. . .
     
partner 2 April 24th, 2021: probable parent nest 60.    
     
pulli May 13th, 2021: 2 cachinnans pulli. May 28th, 2021: cachinnans pullus b[F|0]. May 28th, 2021: cachinnans pullus b[F|1].
 

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.