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 062

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).
  • Location 3 meters west of marked with code "60" on tarmac dam.
  • Cluster of 5 nests within 10 meters range: 3x cachinnans and 2x argentatus, which are extremely difficult to monitor. Next to Angelica is nest 60, next to blackberries complex are nest 62 & nest 63.
  • ID uncertain in 2021, female is probably hybrid Caspian Gull cachinnans (broad medial band on P10, thin broken band on P5).
  • ID uncertain in 2022, same female as in 2021 (probably hybrid Caspian Gull cachinnans with broad medial band on P10, thin broken band on P5). Uncertainty about partner.
  • ID uncertain in 2023, same female as in 2021, trapped in 2023, now r-7.L. Uncertainty about partner. Difficult to monitor exact relations in this cluster of nests.
location April 24th, 2021: cluster of nests. May 1st, 2022: adult female at nest. April 24th, 2021: fight over nest 60-62-63.
 
eggs April 24th, 2021: 3 eggs in nest. May 13th, 2021: probable cachinnans egg. April 19th, 2022: 3 eggs.
 
partner 1 April 24th, 2021: adult female type nest 62??? . .
     
partner 2 May 13th, 2021: adult female hybrid type. May 13th, 2021: adult female hybrid type. May 13th, 2021: adult female hybrid type.
 
partner 2 May 1st, 2022: adult female hybrid type. May 1st, 2022: adult female hybrid type. May 1st, 2022: adult female hybrid type.
 
food May 13th, 2021: prey is Pike perch Sander lucioperca. May 13th, 2021: prey is Rudd Scardinius erythrophthalmus. May 17th, 2022: prey is Rudd Scardinius erythrophthalmus.
 
pulli May 13th, 2021: 2 cachinnans pulli. May 28th, 2021: dead chick in nest 62. May 17th, 2022: chick NLA 5.625.104.
 

Visits and data.

date:                
24-04-2021 2 partners present, both are most likely Caspian Gull cachinnans. But difficult to allocate birds to the nests. Nest allows trapping breeders, but early nest!
  3 eggs in nest.            
  egg no: width (mm) length (mm) volume (cm3):  water test on April 24th:       
  A egg 50,5 75,2 96,56 90 - floating, 3mm above surface      
  B egg 51,8 72,8 98,35 90 - floating, 3mm above surface      
  C egg 51,5 73,6 98,29 90 - floating, 2mm above surface      
  sum nest: 293,20        
   
26-04-2021 Pictures taken from canoe, of several birds flying around nests 60-62-63. How to monitor, telescope?
   
13-05-2021 2 chicks of nest 62 hide underneath Thistle Sircium cover, 45 cm's from nest.
  Fish prey: 1 possible Rudd 25 cm's, 1 week old. 1 predated (?) egg which seems to be cachinnans.
   
15-05-2021 Many fish prey left-overs at nest: small Pike perch Sander lucioperca (taken for analysis).
    mass head+bill (measurements Monika Ballmann)    
  pullus 236 gr 64,1    
  pullus 228 gr 64,1    
                 
    metal tibia head + bill comments:
28-05-2021 pullus .5559412 b-F|0 92,3 Large pullus (16-18 days old), likely cachinnans from nest 60.
  pullus .5559413 b-F|1 95,3 Large pullus, likely cachinnans from nest 60.
  pullus .5559414 b-F|2 75,8 Possibly argentatus, not necessarily from neighbour's nest, b-F|3 broken.
  pullus .5559415 b-F|4 73,2 Possibly argentatus, not necessarily from neighbour's nest, b-F|3 broken.
  pullus .5559416 b-S|3 56,8 Likely argentatus, from neighbour's nest.
  pullus .5559417 b-S|4 57,2 Likely argentatus, from neighbour's nest.
               
08-06-2021 3 adult Caspian Gulls present. No chicks visible from canoe, not on south nor on north side from water. They probably hide in blackberries complex.
   
Visits and data 2022:
Estimation egg laying: A-egg = April 13 2022. Estimating hatching = May 11 2022.
   
12-04-2022 empty nest.
   
15-04-2022 2 eggs in nest.            
  egg no: width (mm) length (mm) volume (cm3):         
15-04-2022 A egg 50,1 68,1 --        
15-04-2022 B egg 51,6 68,4 -- water test on April 27th:       
27-04-2022 C egg 50,3 66,8 -- floating halfway      
  sum nest: --        
   
01-05-2022 Adult at nest 62: very thin line on P5 but clear cachinnans influences
   
09-05-2022 3 eggs: small crack in blue egg.
   
17-05-2022 1 pullus and 2 eggs present.
  prey: half fish at nest probably Rudd.
    metal code darvic mass  
  pullus NLA 5.625.104 - 165 Large pullus (16-18 days old), likely cachinnans from nest 60.
   
22-05-2022 Blue egg still present. No chicks found near nest, but hiding in Blackberry complex.
 
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 ? 62-2023 70,1 51,2 92,52 70,3 51,8 94,98 67,9 51,7 91,38 278,88 same as 2022
ring pulli: -- laying A egg: -- hatch A egg: --
 
catch: date: metal: darvic: mass: wing: head+bill: bill: gonys: greytone:
adult 03-05-2023 6214904 r-7.L nn 466 136 59,7 21,6 6 female cach
pullus 18-05-2023 5556422 G-7|3 116 52,6
 
62-2023
dam: dam 1 west
location: Is nest 62-2021/22. From cluster 60-62-63.
breeders: cach x ?
OBSERVATIONS:
09-04-2023 nest: no eggs, nest is ready.
22-04-2023 nest: 3 eggs, water test = tip bottom 90 degrees; tip bottom 50 degrees, tip bottom 45 degrees.
03-05-2023 adult: trapped female cach: r-7.L.
eggs: 3 eggs.
18-05-2023 eggs: 1 rotten egg.
  pullus: 1 chick ringed is G-7|3, 1 chick dead in nest.