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 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, outside research quadrant. Just 30 meters west of T-split near Elderberry. Discovered late in the season. Code marked at tarmac.
  • ID uncertain, one adult is Caspian Gull cachinnans. Female is argenteus, or with strong argenteus influences.
  • Female 2020 = female 2021 100% certain. Male 2020 is 60% certain male 2021 (limited documentation for 2020).
location Nest near tree April 24th, 2021. Eggs April 24th, 2021: 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: partnerts. .
   
partner 2 May 21st, 2020: cachinnans. April 24th, 2021: cachinnans. May 13th, 2021: cachinnans.
 
pullus May 21st, 2020: pullus b[F|G]. May 21st, 2020: pullus b[F|H]. Food: Round Goby.
 
pullus May 15st, 2021: pullus hatched A-chick. May 28th, 2021: b[F|J] and b[F|K]. June 26th, 2021: b[F|K].
 

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.
               
16-4-2021 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:  
24-4-2021 A 51,9 74,0 100,36 40 - tip bottom    
24-4-2021 B 51,9 75,4 102,26 50 - tip bottom  
24-4-2021 C 51,1 71,8 94,40 30 - tip bottom  
sum nest: 297,02
06-5-2021 Female present. 3 eggs in tact.
13-5-2021 2 partners present. Male is brutal cachinnans.  
15-5-2021 1 egg in tact.  
15-5-2021 1 egg hatching.  
15-5-2021 1 hatched chick. Mass = 75 gr.  
    metal ring darvic ring mass head + bill  
28-5-2021 pullus .5559376 b-F|J 554 85,8 Thrown up prey from chick: worms and fish.
28-5-2021 pullus .5559377 b-F|K 546 83  
           
8-6-2021 No visit.  
metal ring darvic ring mass head + bill wing  
26-6-2021 pullus .5559377 b-F|K 1174 125,5 363 retrapped chick and controlled.