Larus cachinnans in the Netherlands

(last update: August 16, 2020)

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

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Cachinnans - nest Lelystad g-A|G (038)

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 038 positioned at breakwater 2 in 2020, outside research quadrant. Just 30 meters west of T-split near Elderberry. Discovered late in the season. Code marked at tarmac.
  • Nest location of previous years destroyed, this nest is 250 m eastwards in 2022.
  • Nest location 2023 same as 2022.
  • ID 2020 uncertain, one adult is Caspian Gull cachinnans. Female is argenteus-type, with strong argenteus influences.
  • Female 2020 = female 2021 100% certain. Male 2020 is 60% certain male 2021 (limited documentation for 2020).
  • ID 2022: both cachinnans. Female has thinner band on P5, male has more compact band on P5, compared to 2021.
  • ID 2023: female cachinnans & cachinnans hybrid type, as in 2022.
  • ID 2024: female cachinnans & cachinnans hybrid type, as in 2022/2023. In 2024 female trapped:g-A|G.
location Nest near tree April 24th, 2021. April 9th, 2023: nest near rock (same as 2022). April 26th, 2023: nest location.
 
eggs Eggs April 24th, 2021: 3 eggs clutch. Eggs April 26th, 2023: 3 eggs clutch. .
   
partner 1 June 2nd, 2020: hybrid-type. June 2nd, 2020: hybrid-type. June 2nd, 2020: hybrid-type.
 
partner 1 April 24th, 2021: hybrid-type. April 24th, 2021: partners. June 17th, 2022: partners.
 
partner 1 June 17th, 2022: female cachinnans. June 17th, 2022: female cachinnans. April 9th, 2023: female cachinnans.
 
partner 1 April 9th, 2023: female cachinnans. April 23 2024: female cachinnans. April 30 2024: female cachinnans trapped:g-A|G.
 
partner 2 May 21st, 2020: cachinnans. April 24th, 2021: cachinnans. May 13th, 2021: cachinnans.
 
partner 2 June 17th, 2022: male cachinnans. June 17th, 2022: male cachinnans. April 9th, 2023: male cachinnans.
 
partner 2 April 9th, 2023: male cachinnans. April 23 2024: cachinnans, but broad medial band P10. April 23 2024: male cachinnans.
 
pullus May 21st, 2020: pullus b[F|G]. May 21st, 2020: pullus b[F|H]. May 15st, 2021: pullus hatched A-chick.
 
pullus May 28th, 2021: b[F|J] and b[F|K]. June 26th, 2021: b[F|K]. May 22nd, 2022: pullus r-6.R.
 
pullus May 22nd, 2022: pullus r-6.P. 2023 fledged juvenile G-7|2. 2023 fledged juvenile R-8.K.
 
pullus June 18 2024: pullus g-B|N. May 14 2024: pullus g-B|P. June 18 2024: pullus g-B|R.
 
food Food 2020: Round Goby. May 14 2024: Perch and Roach-type. May 14 2024: Chick threw up fish.
 
food June 04 2024: fish = Roach. . .
     

Visits and data.

date:              
21-05-2020 Two pulli found, ringed b[F|G] & b[F|H]. Food: Round Goby, wrap of pork sausage. Both adults overhead alarming. Both unringed.
02-06-2020 Adult with at least one ringed pullus at location. We didn't manage to read the code.
               
16-04-2021 Nest checked. No eggs. Adult present: female cachinnans-type same as last year.
  egg no: width (mm): length (mm): volume (cm3):  water test on April 24th: laying date:  
24-04-2021 A 51,9 74,0 100,36 40 - tip bottom    
24-04-2021 B 51,9 75,4 102,26 50 - tip bottom  
24-04-2021 C 51,1 71,8 94,40 30 - tip bottom  
sum nest: 297,02
06-05-2021 Female present. 3 eggs in tact.
13-05-2021 2 partners present. Male is brutal cachinnans.  
15-05-2021 1 egg in tact.  
15-05-2021 1 egg hatching.  
15-05-2021 1 hatched chick. Mass = 75 gr.  
    metal ring darvic ring mass head + bill  
28-05-2021 pullus .5559376 b-F|J 554 85,8 Thrown up prey from chick: worms and fish.
28-05-2021 pullus .5559377 b-F|K 546 83  
           
08-06-2021 No visit.  
metal ring darvic ring mass head + bill wing  
26-06-2021 pullus .5559377 b-F|K 1174 125,5 363 retrapped chick and controlled.
               

In 2022, construction works (removal of trees and bushes) destroyed old location. In 2022, this nest is in LBBG section, east of T-split on dam 2. Nest with large boulders.
Nest located late in breeding season 2022.

Visits and data 38-2022:

               
metal darvic mass wing H+B  
22-05-2022 pullus .5625166 r-6P 303 58 73,2  
pullus .5625167 r-6R 253 45 71,7  
17-06-2022 2x pullus dead, both r-6P & r-6R. Bird flu?
             
 
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 hybrid 38-2023 69 50 86,85 68,6 52 93,40 67,8 51,9 91,95 272,20 same as 2022
ring pulli: 14-mei laying A egg: 11-apr hatch A egg: 9-mei
     
catch: date: metal: darvic: mass: wing: head+bill:      
Pullus 11-5-2023 NLA 5.556.468 R-8.K (on 18-5) 235 (on 18-5) 67
Pullus 18-5-2023 NLA 5.556.421 G-7|2 152 59,8
Pullus 18-6-2023 NLA 5.556.468 R-8.K 1077 328 122,4
Pullus 18-6-2023 NLA 5.556.421 G-7|2 887 311 112,7
 
038-2023
dam: dam 2 east of T-split
location: 2 large boulders, west one is lookout post, 200 mtr E of T-split, on top of tarmac. Red flag at N-side between blocks.
breeders: cach x river gull
OBSERVATIONS:
09-4-2023 2 adults cach type & river gull type on lookout. No eggs, but nest is ready.
26-4-2023 eggs: 3x egg, measured. Water test: A: floating - halfway
B: 80 - tip bottom
C: floating - 1mm
11-5-2023 pulli: 1 chick ringed, 1 egg hatching, 3rd egg still complete.
18-5-2023 pulli: 2 chicks present (R-8K and unringed one, which is now ringed g-7|2) 1 rotten egg.
18-6-2023 pulli: 2x fledged from nest (1x rotten egg).
25-6-2023 pulli: r-8K present.

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:
g-A|G (038) cach cach-type 70,3 53,3 100,56 68,4 51 89,58 70,6 52,8 99,10 289,23
2024 # eggs A-egg hatch # ringed chicks # all chicks # fledged chicks comments
  3 11-4-2024 9-5-2024
   
dam: dam 2 east of T-split
location: Is 38-2023: 200 mtr E of T-split, on top of tarmac two large boulders, west one is lookout post.
parents? same as 2022, 2023. In 2024 female trapped:g-A|G
   
ring pulli: 14-May
date darvic metal location / nest# species sexe age wing mass head+ bill bill tarsus gonys greyscale
30-04-2024 g-A|G .5625296 Dam 2 soos nest PONT F >4CY 424 1002 125,7 53,5 68,3 19 7
14-05-2024 g-B|N .5631167 nest 38 PONT 1CY 110          
14-05-2024 g-B|P .5631168 nest 38 PONT 1CY 88          
14-05-2024 g-B|R .5631169 nest 38 PONT 1CY 99          
                           
OBSERVATIONS:
12-04-2024 eggs: 1 egg, measured. 
21-04-2024 eggs: 3 eggs, measured. 
30-04-2024 adults: trapped female Caspian Gull, incubating 3 eggs. Now g-A|G.
07-05-2024 nest: 3 eggs, cracks.
14-05-2024 chicks: 3x ringed and measured.
04-06-2024 chicks: 3x ringed chicks present.
18-06-2024 chicks: 3x ringed chicks present.
adult: father guarding chicks.