Larus cachinnans in the Netherlands

(last update: August 16, 2020)

Coordinator:
Albert de Jong
Merijn Loeve
Roland-Jan Buijs
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 for nest 062 uncertain in 2021, female is probably hybrid Caspian Gull cachinnans (broad medial band on P10, thin broken band on P5).
  • ID for nest 062 uncertain in 2022, same female as in 2021 (probably hybrid Caspian Gull cachinnans with broad medial band on P10, thin broken band on P5).
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.
   
date:  
   
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.