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 - nest Lelystad 040

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 040 positioned at tip of T-split, near lighthouse, and in cluster with several Spoonbill nests. Therefore limited visits. Nest occupied: 2021-2023, same location.
  • In 2021: male is Caspian Gull cachinnans. Female is Herring Gull argenteus.
  • In 2022: both female and male are Caspian Gull cachinnans.
  • In 2022: both female and male are Caspian Gull cachinnans.
  • In 2023: no clue on parents, likely same birds. Poorly monitored this season.
location May 28th, 2021: argentatus x cachinnans pulli. April 15th, 2022: nest location April 15th, 2022: nest location.
 
  April 15th, 2022: nest location. April 26th, 2023: 3 eggs. April 19th, 2022: female and male cachinnans.
 
  April 19th, 2022: female and male cachinnans. . .
     
partner 1 May 28th, 2021: sub-adult male cachinnans. April 16th, 2021: sub-adult male cachinnans. May 6th, 2021: partners at nest.
 
female 2022: May 17th, 2022: female cachinnans. May 17th, 2022: female cachinnans. April 27th, 2022: female cachinnans.
 
male 2022: April 27th, 2022: male cachinnans. April 27th, 2022: male cachinnans. May 4th, 2022: male cachinnans.
 
pullus 2022: May 17th, 2022: pullus r[5.L]. May 17th, 2022: pullus r[5.M]. June 21st, 2022: 3rd chick, unringed.
 

Visits and data.

date:              
06-05-2021 Still no visits this season, due to presence of many Spoonbills.
   
13-05-2021 No visit. Camilla is trapping a Spoonbill at dam 1.
   
15-05-2021 Still no visits this season, due to presence of many Spoonbills.
   
28-05-2021 The only real visit this season: 2 pulli in nest.
  metal ring plastic: head+bill:  
pullus .5559420 b-F|6 64,2 F1 hybride argentatus x cachinnans
pullus .5559421 b-F|7 66,6 F1 hybride argentatus x cachinnans
   
08-06-2021 Herring Gull at this location and several alarming Caspian Gulls in the air, probably including partner.

Visits and data 2022 for nest 40:
Estimation egg laying: A-egg = April 12 2022. Estimating hatching = May 10 2022.

    length (mm) width (mm) volume (cm3):  water test on April 15th:     
15-04-2022 A egg 69,9 49 -- --    
  B egg 69 49,6 -- --    
               
19-04-2022 Sub-adult cachinnans n-F|6 is curious and lands on blocks near nest. Fiercy chased away by huge male cachinnans from nest 40. Female is also Caspian.
               
    length (mm) width (mm) volume (cm3):  water test on April 27th:     
27-04-2022 A egg     -- 3 mm - floating    
  B egg     -- 3 mm - floating    
  C egg 67,2 49,5 -- 3 mm - floating    
   
04-05-2022 From distance: male cachinnans circles over nest and lands on lighthouse as lookout post.
   
17-05-2022 From distance: female cachinnans circles over nest few times.
    metal darvic mass      
  pullus NLA 5625110 r-5M 200      
  pullus NLA 5625111 r-5L 136      
   
17-06-2022 From distance: both cachinnans parents near nest, with 3 chicks. Of course, one is unringed..
  r-5M and r-5L can fly around, pretty well.
   
21-06-2022 r-5M and r-5L and their unringed sibling fly around and swim on west side of nest, near yellow buoy. 3 Chicks fledged.
   
28-06-2022 male cachinnans near nest.
 
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?
cach x cach 40-2023 69,5 50 87,48 68,6 50,3 87,39 65,2 48,7 77,86 252,73 same as 2022
 
40-2023
dam: dam 1 T split
location: S of Elder bush (Vliertje), 15 m south of tower. Same as 40-2021/2022.
breeders: cach x cach
OBSERVATIONS:
26-4-2023 adult: Unringed cach present at location, guarding at block on E-side.
nest: Exact same spot as 2022.
eggs: 3x egg, measured. No water test.
27-5-2023 nest: Nest empty, no chicks found.
Very poor monitoring this season, partly due to many Spoonbills & Little Egrets in this section. No clue on hatched or fledged chicks 2023.