Larus cachinnans in the Netherlands

(last update: August 16, 2020)

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

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Cachinnans hybrid - nest Lelystad y-X71A

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 y-X71A positioned in section dam 1 south. Nest at edge of Blackberry complex, at transition to tarmac dam, about 25 meters west of nest n-F|N.
    In 2023 approx at same location.
  • ID uncertain in 2022, one partner is male hybrid cachinnans y-X71A. Partner most likely Herring Gull.
  • ID uncertain in 2023, one partner is male hybrid cachinnans y-X71A. Partner is Herring Gull.
  • ID uncertain: this year no observations of y-X71A.
location May 4th, 2022: 3 eggs at nest. May 4th, 2022: nest location. May 4th, 2022: y-X71A at nest.
 
partner 1 May 4th, 2022: y-X71A at nest. May 4th, 2022: y-X71A at nest. May 1st, 2022: y-X71A with possible Herring Gull partner.
 
  April 11th, 2022: male is hybrid Caspian Gull y-X71A. April 15th, 2022: male is hybrid Caspian Gull y-X71A. April 27th, 2022: male is hybrid Caspian Gull y-X71A.
 
  April 27th, 2023: 6CY male is hybrid Caspian Gull y-X71A. April 9th, 2023: 6CY male is hybrid Caspian Gull y-X71A. .
   
partner 2 April 09 2023: partner is female Herring Gull. April 09 2023: partner is female Herring Gull. .
   
food May 30th, 2022: food is Eel. . .
     

Visits and data:
Estimation egg laying: A-egg = April 26 2022. Estimating hatching = May 24 2022.

date            
27-04-2022 Again, y-X71A standing high on dam, guarding the area.
  Nest located here with 1 egg. Label: nest 119Z (part of control group Herring Gulls).
  1 egg egg no: width (mm) length (mm) volume (cm3):  water test on April 27th: 
    A egg 51,2 71,2 -- 00 - tip on bottom
             
01-05-2022 y-X71A standing high on dam, about 25 meters from nest 61, near 119Z. y-X71A classified as male cachinnans hybrid..
             
04-05-2022 y-X71A steps from nest, was breeding. Code 119Z sprayed near nest.
  3 eggs egg no: width (mm) length (mm) volume (cm3):  water test on May 4th: 
    A egg 51,2 71,3 -- --
    B egg 47,7 68,8 -- --
    C egg 47,5 65,8 -- --
   
09-05-2022 3 eggs.
   
17-05-2022 3 eggs.
   
22-05-2022 3 eggs. First crack in shell. Decided not to try to trap adult at nest. y-X71A present.
   
30-05-2022 1 chick present: chick r-5+ (which belongs to nest 117Z). No chicks of nest 119Z found in vegetation.
  food: large Eel (25 cm's) next to nest. No sign of adults.
   
  In 2022 no chicks ringed in this nest and no data on fledging.
 
 
 
egg sizes & volume 2023
SPECIES NEST A_length A_width A_volume B_length B_width B_volume C_length C_width C_volume TOTAL NEST: known parents?
hybrid x teus X71A 73,4 51 96,12 73,2 50,8 95,11 70,8 48,4 83,51 274,74 same as 2022
ring pulli: 20-mei laying A egg: -- hatch A egg: --
 
X71A 122-2023
dam: dam 1 west
location: Coded 122 on tarmac, nest is next to sprayed white spot
breeders: hybrid x teus
OBSERVATIONS:
05-04-2023 adult:  yX71A present.
09-04-2023 nest:  seems ready.
adult:  Male is yX71A, female is teus. Guarding on top of dam.
22-04-2023 nest:  3 eggs, watertest: tip at bottom 70, 50, 20 degrees respectively.
27-04-2023 adult:  Male is yX71A, female is argenteus. Guarding on top of dam.
03-05-2023 adult:  Cage on nest 119 border tarmac-vegetation (was location 119-2022). Now trapped a LBBG here.
X71A moved to location 122-2022? In retrospect: yes.
25-06-2023 adult:  X71A present on dam, unknown if he has any chicks.

Visits and data 2024.

NEST code parent 1 parent  2 A_length A_width A_volume B_length B_width B_volume C_length C_width C_volume TOTAL NEST:
119-2024 teus teus 65,1 48,6 77,42 67,5 47,7 77,33 0,00  
  # eggs A-egg hatch # ringed chicks # all chicks # fledged chicks comments
  2    
   
dam: dam 1 south
location: dam 1 western section, nest 119-2023, was y-X71A in 2023
parents? one same as 2023?
   
ring pulli: June 03?
date darvic metal location / nest# species sexe age wing mass head+ bill bill tarsus gonys greyscale
                           
OBSERVATIONS:
05-05-2024 eggs 2x, measured.