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 061 tibia r[F.B]

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 marked with code "61" on tarmac dam.
  • Nest 061 "r-F.B" on breakwater dam 1 south section, most western cachinnans nest. Easy to trap the adults here; female trapped in 2021 and ringed r-F.B.
  • ID certain in 2021, both breeders are Caspian Gull cachinnans. Male is aged "5CY", on pattern of primary coverts.
location April 24th, 2021: red spray "61". April 24th, 2021: red spray "61". April 26th, 2021: guarding male, breeding female.
 
  May 13th, 2021: female guarding, male in nest. . .
     
eggs April 24th, 2021: 2 eggs in nest. April 24th, 2021. May 13th, 2021: 3 eggs in nest.
 
partner 1 April 26th, 2021: male cachinnans 5CY. April 26th, 2021: male cachinnans 5CY. May 13th, 2021: male cachinnans.
 
partner 2 May 13th, 2021: female cachinnans. May 13th, 2021: female cachinnans. May 13th, 2021: female cachinnans.
 
  May 28th, 2021: Roland-Jan Buijs & Mars Muusse. May 28th, 2021: Roland-Jan Buijs & Albert de Jong. May 28th, 2021: female cachinnans r-F.B.
 
pullus May 28th, 2021: cachinnans pullus r[F.Y]. . .
     

Visits and data.

date:                
24-04-2021 2 partners present, both cachinnans. Nest allows trapping breeders, easily.
  2 eggs in nest.            
  egg no: width (mm) length (mm) volume (cm3):  water test on April 24th:       
  A egg 50,8 71,8 93,29 30 - tip bottom      
  B egg 49,7 70,4 87,56 25 - tip bottom      
  sum nest: --        
   
26-04-2021 Both partners present, one guarding, one breeding. A female cachinnans with hanging left leg in flight is most probably NOT the breeding female. Is another cachinnans breeding here as well?
   
13-05-2021 Both partners present. Male has 5CY markings. Now the right female photographed in flight.
  3 eggs in nest.
   
15-05-2021 3 eggs in nest.
   
28-05-2021 3 eggs in nest.
  Cage placed and one bird (female) trapped for ringing.
    metal tibia mass head + bill wing tarsus bill
  adult .5559427 r-F.B 1030 124 454 69,7 59,8
                 
08-06-2021 Both partners present. At least 2 chicks around.
                 
    metal tibia mass head + bill wing  
26-06-2021 pullus .5550695 r-F.Y 649 90,4 157 most likely cachinnans chick of nest 61.
  pullus .5550696 r-F.Z 1126 111,8 260 argentatus, near nest 61, from neighbouring nest.
  pullus .5550697 r-F.1 1036 108,6 269 argentatus, near nest 61, from neighbouring nest.
  pullus .5550698 r-F.2 879 98,4 230 argentatus, near nest 61, from neighbouring nest.