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 018

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 018 positioned at breakwater 2, behind coded block "18" and about 25 meters west of nest 15 (also code on block "15"). In 2022 nest temporarily coded as "226".
  • ID uncertain in 2020: male is Caspian Gull cachinnans, but partner not known.
  • ID certain in 2021: same male Caspian Gull cachinnans as previous year. Partner in 2021 is female Herring Gull (type).
  • ID certain in 2022: same male Caspian Gull cachinnans as previous year. Partner again is female Herring Gull (type).
location March 30th, 2021. April 29th, 2022: mixed couple. April 29th, 2022: 3 eggs.
 
partner 1 May 7th, 2020: male cachinnans 5CY? May 7th, 2020: male cachinnans 5CY? April 26th, 2021.
 
partner 1 April 26th, 2021. April 26th, 2021. April 26th, 2021.
 
  June 8th, 2021. April 29th, 2022: Caspian Gull male. .
   
partner 2 May 6th, 2021: Herring Gull (type). . .
     
partner 2 April 29th, 2022: Herring Gull female. April 29th, 2022: Herring Gull female. April 29th, 2022: Herring Gull female.
 
eggs Eggs April 15th, 2020: 1 egg clutch. Eggs April 27th, 2020: 3 eggs clutch. April 29th, 2022: 3 eggs.
 

Visits and data.

date:            
  egg no: width (mm) length (mm) volume (cm3):  water test on April 15th:  
15-04-2020 A 50,3 70,6 89,94 90 - floating, 22mm above surface 1 egg in nest.
             
27-04-2020 B 50,3 73,3 93,38 90 - tip on bottom 3 eggs in nest.
  C 48 70 81,20 90 - tip on bottom
  sum nest: 264,52
21-05-2020 --     Nest not visited.
         
date:  
   
30-03-2021 Adult Herring gull and adult Caspian Gull at block 18.
   
24-04-2021 Adult bird at blocks. Dam not entred to look for nest 18, but observation from canoe.
  Closeby, just behind 18 is also nest 13, which was not checked!
   
06-05-2021 Nest located and eggs measured.
  One parent is female Herring Gull. Other parent is male Caspian Gull.
  egg no: width (mm) length (mm) volume (cm3):  water test on May 6th:  3 eggs in nest.
  A 47,9 70,1 80,98 floating - 4 mm.  
  B 50,0 72,9 91,76 floating - 4 mm.  
  C 47,4 68,1 77,04 floating - 1 mm.  
         
15-05-2021 3 eggs present.
         
28-05-2021 Empty nest.
         
08-06-2021 Male cachinnans is attacking the canoe. Protecting chicks?
  No chicks present.
   
date:  
   
29-04-2022 Nest located and eggs measured.
  One parent is female Herring Gull. Other parent is aggressive male Caspian Gull.
  egg no: width (mm) length (mm) volume (cm3):  water test on May 6th:  3 eggs in nest.
  A 48,6 72,9 -- floating - halfway.  
  B 47,8 70,5 -- 90 - tip bottom.  
  C 48,7 71,4 -- 90 - tip bottom.