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 013

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 013 positioned on top of breakwater 2. Behind nest 18, just and a few meters eastwards.
  • By May 2020, area also occupied by Little Egrets and Spoonbills, therefore no controls after May 1st.
  • In 2021, nest was added to control list quite late, 1st week of May.
  • Uncertainty on ID in 2020, one parent is Caspian Gull cachinnans type, or just within hybrid zone. Other parent not photographed.
  • Uncertainty on ID in 2021, one parent is probably same bird, again Caspian Gull cachinnans type or just within hybrid zone. Possible partner may be sub-adult Herring Gull type.
location Eggs April 15th, 2020: 1 egg clutch. Eggs April 27th, 2020: 3 eggs clutch.  
   
partner 1 May 7th, 2020. May 7th, 2020. May 7th, 2020.
 
partner 1 April 26th, 2021: possible bird for nest 13. May 6th, 2021. May 6th, 2021.
 
partner 2 May 28th, 2021: possible partner nest 13. May 28th, 2021: possible partner nest 13. May 28th, 2021: possible partner nest 13.
 
pullus May 28th, 2021: pullus b[F|R]. May 28th, 2021: pullus b[F|S]. May 28th, 2021.
 

Visits and data.

date: egg no: width (mm) length (mm) volume (cm3):  water test on April 27th:  
15-04-2020 A 51,4 71,2 94,71 90 - tip on bottom 1 egg in nest.
           
27-04-2020 B 51,1 72,2 94,92 90 - tip on bottom Now 3 eggs in nest.
  C 49,8 68,5 85,54 60 - tip on bottom  
  sum nest: 275,17
21-05-2020 ?? Nest not checked as there are Spoonbills and Little Egrets breeding there too now.
   
   
date:    
26-04-2021 Adult bird landed on this location. First indication of occupied nest.
   
egg no: width (mm) length (mm) volume (cm3):  water test on April 27th:
06-05-2021 A egg 76,1 50,0 95,79 4 mm - floating 3 eggs in nest.
B egg 76,9 48,2 89,95 4 mm - floating
C egg 73,8 48,7 88,13 1 mm - floating
   
15-05-2021 Nest missed in control.
     
28-05-2021 metal tibia mass head + bill possible parent: Herring Gull type sub-adult.
pullus .5559402 b-F|P 210 58,8
pullus .5559403 b-F|R 190 67,2
pullus .5559404 b-F|S 185 65,2
     
08-06-2021 No visit. Spoonbill breeding here.
     
26-06-2021 No visit.