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 De Kreupel X804 20

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 on island "M", positioned at west side.
  • One parent is okay for pure cachinnans, yellow X804 from Germany.
  • Other parent seems to have no black on P5 and too much black at P10 for pure cachinnans.
  • One juvenile ringed: pale blue F+. Tertials with notched fringes and pattern on inner primaries hint to hybrid cachinnans.
location Parent 1: y[X804]. Date: June 12th, 2020. Parent 2: unringed. Date: June 12th, 2020.  
   
pullus May 21st, 2020 pullus p[F+].    
     
juveniles June 12th, 2020 pullus p[F+].    
 
 
     

Visits and data.

date:             Comments:    
   
24-4-2020 Attempt to trap parents at nest. Unsuccessful. Three warm eggs at nest.
               
  egg no: width (mm): length (mm): volume (cm3):       
21-5-2020 B 50,0 71,9 130,14 Cold egg.   1 pullus ringed. Two eggs cold.
21-5-2020 C 49,1 68,7 116,68 Cold egg.   1 pullus ringed. Two eggs cold.
    WING: HEAD + BILL: BILL: WEIGHT:  
21-5-2020 pullus NLA 5.545.430 & p[F+] -- 78.0 30.7 356 1 pullus ringed. Two eggs cold.
                 
12-6-2020 pullus NLA 5.545.430 & p[F+] 294.5 114.7 47.5 880