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 163

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 163 positioned on section "dam 1 blocks", in NW part, below (north) of nest 53. Confusion in 2023 about which parents belong to which nest.
  • ID uncertain in 2023: one parent is sub-adult Caspian Gull cachinnans. Finally, agreed upon chicks r-87 and r-88 belowng to nest 53.
partner 1 May 13th, 2023: adult cachinnans. May 13th, 2023: adult cachinnans. May 13th, 2023: adult cachinnans.
partner 2 May 13th, 2023: sub-adult cachinnans. May 13th, 2023: sub-adult cachinnans. May 13th, 2023: both parents are cachinnans.
pullus July 8th, 2023: weak juvenile r[8.7]. July 15th, 2023: juvenile r[8.8].  

Visits and data:

egg sizes & volume 2023
cach x cach type 163-2023
163-2023 uncertainty about chicks: decision = nest 053.
dam: dam 1 
location: Blocks dam 1 - west section, under (north of) nest 53.
breeders: cach x cach type
11-05-2023 pull 2 chicks ringed.
18-05-2023 puli R-87 was present
27-05-2023 pull Low on N-side, found again r-87 & r-88 from nest 163 (or from 53)? See notes on tab 53.
18-06-2023 pull r88 might be hybrid? Op blokken dam 1, west stuk, laag, op noord (dus wrschl niet van nest 53?), maar klimt omhoog.
25-06-2023 pull r-88 and r-87 both present
53-2023 / 163-2023 (likely 2 nests, but maybe all data for 1 pair only).
dam: dam 1 blocks
location: is nest 53/110, same as 2021/2022. Later in season chicks ringed little north of this spot, but then no Caspians higher on dam. Same couple?
breeders: cach x cach
26-4-2023 nest: Refreshed red stripe on block, nest is 1,5 m south of red stripe.
eggs: 3x egg, measured. No water test.
11-5-2023 nest: 1 egg hatching, other 2 still complete, but many nests here. If this is the wrong nest, then maybe R-87 & R-88 from nest 163? In retrospect: yes, likely of 163.
18-5-2023 nest: Empty, no chicks found.
27-5-2023 nest: No shit at nest, no traces of chicks. Low on N-side, found again R-87 & R-88 from new nest number 163 (and likely not from 53)?
18-6-2023 pull: R-88 might be hybrid? See nest 163 (which is north of 53), for details on R-8.7 and R-8.8. Present on N-side, but walks up to location nest 53!