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 029

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).
  • Nest 029 positioned at breakwater 1, near nest 3 and nest 30 (which is a LBBG nest, with large code on block).
  • ID 2020 certain, both Caspian Gull cachinnans. Female known as 'the thayeri'. ID in 2021: same adults.
  • 5 eggs, one Lesser Black-backed Gull very aggressive and close to nest. The 2nd partner responsible for the extra eggs??? In 2021 the LBBG of nest 30 present again too.
location April 27th, 2020: nest location. April 16th, 2021. .
   
eggs May 7th, 2020: 5 eggs clutch. April 16th, 2021: 1 egg present. April 24th, 2021: 3 eggs clutch.
 
partner 1 2020 female cachinnans with thayeri. 2020 female cachinnans with thayeri. April 16th, 2021 female cachinnans with thayeri.
 
  April 16th, 2021 female cachinnans with thayeri.    
     
partner 2 May 7th, 2020: male cachinnans with yellow legs. May 7th, 2020: male cachinnans, always fighting the LBBG. .
   
  April 26th, 2021: male cachinnans with yellow legs. April 26th, 2021: male cachinnans with yellow legs. .
   
pullus May 21st, 2020: pullus n[F|U]. September 11st, 2020: exit pullus n[F|U]. .
   

Visits and data.

date: egg no: width (mm) length (mm) volume (cm3):  water test on April 27th:  
07-05-2020 A 51,3 72,8 96,46 90 - floating, 7mm above surface 5 eggs in the nest, both partners cachinnans, with LBBG close by.
07-05-2020 B 51,9 71,8 97,38 90 - floating, 7mm above surface  
07-05-2020 C 46,3 65 70,16 90 - off bottom, halfway
07-05-2020 D 51,7 73,9 99,45 90 - floating, 5mm above surface
07-05-2020 E 50 65,3 82,20 90 - tip on bottom  
      sum nest: --    
21-05-2020 --     Egg A, B, C rotten but intact. One pullus, ringed n[F|U].
         
11-09-2020 --     Rotten egg in nest. Also in nest: tibia bone + ring of n[F|U].
         
date:        
  egg no: width (mm) length (mm) volume (cm3):  water test on April 16th:  
16-04-2021 A 51,7 73,1 96,46 00 - flat on bottom (just laid) 1 egg in nest
  1 adult ast nest. Again female cachinnans AKA the thayeri.
         
  egg no: width (mm) length (mm) volume (cm3):  water test on April 24th:  
24-04-2021 A 51,7 73,1 98,38 90 - tip on bottom  
  B 50,5 74,6 95,79 45 - tip on bottom  
  C 49,3 72,8 89,09 30 - tip on bottom  
      sum nest: 283,26    
         
24-04-2021 male cachinnans at nest.
         
13-05-2021 No visit, Camilla is trapping a Spoonbill.
         
15-05-2021 No visit, thunder rolling in.
         
28-05-2021 2 eggs in nest. Infertile?
         
08-06-2021 male guarding near nest, female 'the thayeri' at nest. Still trying to incubate?