Larus cachinnans in the Netherlands

(last update: August 16, 2020)

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


Cachinnans - nest Lelystad 057 y[P:A02]

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 057 positioned at breakwater dam 2, close to nest 11, marked with red flag. Many Spoonbills breeding in this section.
  • ID certain: partners are cachinnans, one bird is male 5CY y[P:A02] and one is female near-adult (5CY?) unringed cachinnans.

Metal ring PLG DN34502 and yellow P:A02, ringed as pullus on May 25 2017 in a mixed Caspian Gull colony "Larus cachinnans kolonia" with cachinnans dominance,
at ZB. KOZIELNO, PACZKÓW, POLAND, by ringers Jacek Betleja & Mateusz Ledwoń. In all respects, y[P:A02] is cachinnans, no indication for hybrid.

location March 30th, 2021. April 24th, 2021.  
eggs April 24th, 2021: using Spoonbill nest. April 24th, 2021: 3 eggs clutch. .
partner 1 March 30th, 2021: 5CY y[P:A02]. March 23rd, 2021: easy on bread. .
  March 30th, 2021. March 30th, 2021.  
partner 2 March 30th, 2021: some black on primary coverts. March 30th, 2021.  

Visits and data.

24-03-2021 y[P:A02] resting at dam 1. Together with 4CY cachinnans w[327:U], 4CY cachinnans y[P:U60], and more cachinnans, easy on bread.
Later resting at dam 2 near nest 11.
30-03-2021 y[P:A02] resting breakwater dam 2 close to nest 11, now with potential partner.
16-04-2021 No visit.
24-04-2021 3 eggs in nest.
egg no: width (mm) length (mm) volume (cm3):  water test on April 24th:   
A egg 52,3 72,2 99,44 15 - tip on bottom  
B egg 49,5 71,8 88,58 20 - tip on bottom  
C egg 51,4 69,2 92,05 20 - tip on bottom
26-04-2021 No visit. Camilla is trapping a Spoonbill.
13-05-2021 No visit.
15-05-2021 3 eggs in nest, 1 egg has scratches will hatch soon (= A egg).
28-05-2021 Food prey in nest is fish: Rounded Goby.
  There are chicks around, but not found in dense vegetation.
08-06-2021 No parents present. No chicks either.
26-06-2021 No activity near nest.