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 046

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 046 positioned high on artificial breakwater dam 2, nest between large blocks (temporarily labeled "nest 18 2021").
  • ID in 2021 certain: both partners are Caspian Gull cachinnans. This was nest 37 in 2020.
  • Nest marked with red flag from flotsam and jetsam nearby nest.
location Nest between blocks April 24, 2021 (with Albert de Jong). Eggs April 16th, 2021: 3 eggs clutch. Eggs April 16th, 2021: "the giant egg".
 
partner 1 April 24th, 2021: partner 1 = cachinnans. April 24th, 2021: partner 1 = cachinnans. .
   
partner 2 April 24th, 2021: partner 2 = cachinnans. April 24th, 2021: partner 2 = cachinnans. April 24th, 2021: partner 2 = cachinnans.
 
pullus May 15th, 2021 fat pulli, much fish. May 15th, 2021 Roach or Rudd (no head). .
   

Visits and data.

date:              
  egg no: width (mm): length (mm): volume (cm3):  water test on April 16th: laying date:  
16-4-2021 A 51,8 83,7 113,08 90 - tip bottom   "the giant egg"!!!
16-4-2021 B 48 75,6 87,70 20 - tip bottom  
16-4-2021 C 48,1 73,5 85,62 35 - tip bottom  
sum nest: 286,40
   
24-4-2021 2 eggs, giant egg disappeared! water test on April 24th:  
24-4-2021 B egg 75 - tip bottom  
24-4-2021 C egg 90 - tip bottom  
26-4-2021 2 partners present.  
    mass  
15-5-2021 pullus 114 Food around nest: fish. Round Goby & Roach or Rudd (no head)
15-5-2021 pullus 172 Roach/Rudd probably from fishermen trap (dead by-catch).
    metal ring darvic ring mass head + bill  
28-5-2021 pullus .5559381 b-F|L 583 90,3 Food around nest: fish. Pike Perch & Roach (extremely unlikely
    parents caught this, must have been by-catch from fishermen).
           
08-6-2021             No visit.
26-6-2021             No chicks found, despite intensive search between blocks.
              Intense smell of fish and lots of left-overs. No alarming parents.