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 015

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 015 positioned at breakwater 2, just west of nest 017 (which has a huge mark on a block), hidden behind small prunus (avium?).
  • ID uncertain, on April 27th 2020, a bird took off the nest with much black on P10 and broad band on P5. This is partner 1 (female). Partner 2 is cachinnans.
  • Male 2020 is same male 2021. Also female 2020 is same as female 2021.
location Nest on May 7th, 2020. Eggs April 15th, 2020: 3 egg clutch. May 13th, 2021 guarding cachinnans and michahellis (nest45).
 
location April 16th, 2021. Eggs April 16th, 2021: 3 egg clutch. May 15th, 2021: 1 cold egg & Roach (or Rudd hybrid).
 
partner 1 May 7th, 2020: P9-P10 pattern diagnostic. May 7th, 2020: Caspian Gull type.  
  \  
partner 1 May 13th, 2021: Caspian Gull type. May 13th, 202: P9-P10 pattern diagnostic. May 13th, 2021: Caspian Gull type.
 
partner 2 May 7th, 2020. May 7th, 2020. .
   
partner 2 April 26th, 2021: guarding female and male has a look too. April 26th, 2021. April 26th, 2021.
 
pullus May 28th, 2021: b[F|M]. May 28th, 2021: b[F|N]. .
   

Visits and data.

date:            
  egg no: width (mm) length (mm) volume (cm3):  water test on April 27th:  
15-04-2020 A 51,5 70,6 94,28 90 - floating, 3mm above surface  
  B 51,8 72,1 97,41 90 - floating, 3mm above surface  
  C 50,7 70,2 90,86 90 - floating, 3mm above surface  
  sum nest: 282,54
27-04-2020     One parent with much black on P10 and broad band on P5.
21-05-2020 pullus     Failed nest. No pulli, no shit, no food left-overs.
         
16-04-2021 egg no: width (mm) length (mm) volume (cm3):  water test on April 16th:  red flag 15 placed near nest.
  A egg 52,6 70,6 98,35 50 - tip bottom  
  B egg 51 72 94,29 40 - tip bottom  
  C egg 50,5 74,5 95,66 35 - tip bottom  
      sum nest: 288,30    
24-04-2021 2 eggs.     1 adult at blocks, guarding from look-out.
26-04-2021 Herring Gull tolerated on block in front of nest. Probably Herring from nest 15B.
  Also, female on look-out and male leaves the nest for a short break or to check everything is okay.
13-05-2021 Female often on look-out block close to block 17, raising confusion if this is the partner of nest 17.
15-05-2021 1 egg cold, unfertile. Measurements Monika Ballmann: 73.2x50.4 (probably labeled C-egg in April)
  2 chicks present in nest: Mass = 232 gr & Mass = 193 gr.
  Food in nest: Roach (this is often a fishermen's by-catch from traps 200 meters from the nest).
28-05-2021   metal tibia mass head + bill 2 chicks ringed.
  pullus .5559385 b-F|M 707 86,3  
  pullus .5559386 b-F|N 730 93,7  
08-06-2021 Both pulli swimming 100 meters from waterfront, right between dams with large bulkships approaching. Protected by 1 parent, made their way back to dam 2.
26-06-2021 Nest abandoned.