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 001

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 001 positioned high on artificial breakwater in reedbed, between some small Elderberry bushes and dense Blackberry vegetation.
  • ID in 2020 uncertain, presumed breeders are Caspian Gull cachinnans adult x Yellow-legged Gull michahellis 4CY.
  • Nest in dense cluster of several nests; from the water it proved to be difficult to pin down the parents for this particular nest in 2020.
  • ID in 2021 uncertain, adult female is pure Caspian Gull cachinnans, adult male most likely Caspian Gull cachinnans too.
location Nest in vegetation. April 26th, 2021: nest location. April 26th, 2021: nest location.
 
eggs Eggs April 15th, 2020: 2 eggs clutch. Eggs April 27th, 2020: 3 eggs clutch.  
   
partner 1 2020 date: ? (presumed nest 1 breeder). June 02 2020, micha-type at nest or neighbour? .
   
partner 1 2021 April 26th, 2021: male. April 26th, 2021: male. .
   
partner 2 date: ? (uncertain nest 1 breeder). date: ? (uncertain nest 1 breeder). April 15th, 2020 (uncertain nest 1 breeder).
 
partner 2 2021 April 26th, 2021: female. April 26th, 2021: female. April 26th, 2021: female.
 
pullus May 21st, 2020 pullus n[F|Y]. . .
     

Visits and data.

date: egg no: width (mm): length (mm): volume (cm3):  water test on April 27th: laying date:  
15-04-2020 A 51,9 72,7 98,60 90 - 1mm floating    
  B 49,7 73,2 91,04 90 - tip bottom  
             
27-04-2020 C 48,2 76,5 89,49 90 - tip bottom  
sum nest: 279,12
     
21-05-2020 pullus Empty nest, 1 chick within 1 meter of nest, ringed n[F|Y].
     
date:    
26-04-2021 One partner on look-out stone (shit-block).
  One partner alarming, reluctant to leave the nest. Must have eggs, but nest not searched.
     
06-05-2021 egg no: width (mm): length (mm): volume (cm3):  water test on April 27th:  
  A 50,5 74,1 95,15 90 - 4mm floating  
  B 50,6 73,2 94,37 90 - 2mm floating  
  C 50,7 72,8 94,22 90 - 1mm floating  
sum nest: 283,73
   
15-05-2021 No visit.
     
28-05-2021 Empty nest. Chicks not found in dense vegetation.
     
08-06-2021 No birds near nest. Have they moved with chicks to north side of dam? Later: no birds found at north side.
 
26-06-2021 No visit.