Larus cachinnans in the Netherlands

(last update: August 16, 2020)

Albert de Jong
Merijn Loeve
Roland-Jan Buijs
Leon Kelder
Mars Muusse



Cachinnans - nest Lelystad 033

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 033 positioned at breakwater 1, two meters from nest 34. High on breakwater, between large blocks.
  • ID in 2020 certain, both Caspian Gull cachinnans, one parent has sub-adult patterns in wing.
  • ID in 2021 cetrain, both Caspian Gull cachinnans. But are these the same two birds as in 2020?
partner 1 2020 May 7th, 2020: male cachinnans. May 7th, 2020: male cachinnans.
partner 1 2021 April 26th, 2021: male & female cachinnans. April 26th, 2021: female cachinnans.
partner 2 2020 June 2nd, 2020: hybrid-type female cachinnans, wrong bird? June 2nd, 2020: hybrid-type female cachinnans.
partner 2 2021 April 26th, 2021: male cachinnans. .
pullus May 21st, 2020: pullus n[F|5]. May 21st, 2020: pullus n[F|6].

Visits and data.

date: egg no: width (mm) length (mm) volume (cm3):  pulli:  
07-05-2020 A       wet chick - 1 day old. 1 egg & 2 chicks in the nest, both partners cachinnans.
07-05-2020 B       chick - 3 days old.  
07-05-2020 C       hatching egg - tiny hole.
21-05-2020 pulli     Nest empty, two chicks found, ringed n[F|5] & n[F|6].
26-04-2021 male and female Caspian Gull present. One with subadult pattern. No marking placed near look-out stone.
13-05-2021 no visit, Camilla is trapping a Spoonbill.
15-05-2021 location visit. Walking between stones not certain which is the correct nest. Many surrounding Lesser Black-backed nests.
28-05-2021 location visit to do ringing, but uncertainty about exact location. We should spray and mark this location in the future to have a clue.
08-06-2021 no visit.