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 046

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 046 positioned high on artificial breakwater dam 2, nest between large blocks (temporarily labeled "nest 18 2021"). Nest marked with red flag from flotsam and jetsam nearby nest.
  • Same location in 2022. No eggs this season, but occupied territory for entire period.
  • Same location in 2023.
  • ID in 2021 certain: both partners are Caspian Gull cachinnans. This was nest 37 in 2020.
  • ID in 2022 certain, same male and female cachinnans as 46-2021.
  • ID in 2023 certain, same male and female cachinnans.
location Nest between blocks April 24, 2021 (with Albert de Jong). Eggs April 16th, 2021: 3 eggs clutch. Eggs April 16th, 2021: "the giant egg".
 
  April 26th, 2023: 1 egg. April 26th, 2023: 1 egg. April 26th, 2023: 1 egg.
 
partner 1 April 24th, 2021: partner 1 = cachinnans. April 24th, 2021: partner 1 = cachinnans. April 29th, 2022: cachinnans partners.
 
partner 1 April 29th, 2022: partner 1 = cachinnans (same as 2021). April 29th, 2022: partner 1 = cachinnans (same as 2021). .
   
partner 1 May 13th, 2023: partner 1 = cachinnans. May 13th, 2023: partner 1 = cachinnans. May 13th, 2023: partner 1 = cachinnans.
 
partner 2 April 24th, 2021: partner 2 = cachinnans. April 24th, 2021: partner 2 = cachinnans. April 24th, 2021: partner 2 = cachinnans.
 
partner 2 April 29th, 2022: partner 2 = cachinnans (same as 2021). April 29th, 2022: partner 2 = cachinnans. mat 4th, 2022: partner 2 = cachinnans.
 
partner 2 May 13th, 2023: partner 2 = cachinnans. May 13th, 2023: partner 2 = cachinnans. .
   
pullus May 15th, 2021 fat pulli, much fish. February 23,rd, 2022: b[F|L] in Portugal. May 15th, 2021 Roach or Rudd (no head).
 

Visits and data.

date:              
  egg no: width (mm): length (mm): volume (cm3):  water test on April 16th: laying date:  
16-4-2021 A 51,8 83,7 113,08 90 - tip bottom   "the giant egg"!!!
16-4-2021 B 48 75,6 87,70 20 - tip bottom  
16-4-2021 C 48,1 73,5 85,62 35 - tip bottom  
sum nest: 286,40
   
24-4-2021 2 eggs, giant egg disappeared! water test on April 24th:  
24-4-2021 B egg 75 - tip bottom  
24-4-2021 C egg 90 - tip bottom  
26-4-2021 2 partners present.  
    mass  
15-5-2021 pullus 114 Food around nest: fish. Round Goby & Roach or Rudd (no head)
15-5-2021 pullus 172 Roach/Rudd probably from fishermen trap (dead by-catch).
    metal ring darvic ring mass head + bill  
28-5-2021 pullus .5559381 b-F|L 583 90,3 Food around nest: fish. Pike Perch & Roach (extremely unlikely
    parents caught this, must have been by-catch from fishermen).
           
08-6-2021             No visit.
26-6-2021             No chicks found, despite intensive search between blocks.
              Intense smell of fish and lots of left-overs. No alarming parents.
   
15-4-2022 nest ready, no eggs.
               
29-4-2022 no eggs. 2x cachinnans parents at nest site.
               
04-5-2022 no eggs. 2x cachinnans present. Today we discovered a 2nd nest, 5 mtr east. Can this be the future nest for 2022.
               
02-6-2022 no eggs. 2x cachinnans present.
               
28-6-2022 no eggs. 2x cachinnans present.
 
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 cach 46-2023 77 45,3 79,56 0 0 0,00 0 0 0,00 79,56 same as 2022
ring pulli: 31-mei laying A egg: 26-apr hatch A egg: 24-mei
 
46-2023
dam: dam 2 east
location: nest 'red corner-flag', westernmost nest on blocks-east, no eggs in 2022
breeders: cach x cach
OBSERVATIONS:
04-4-2023 adult: 2 adults.
09-4-2023 adult: 2 adults.
nest: nest is ready, no eggs.
26-4-2023 nest: 1 egg, measured. No water test. Very slender, blue egg.
11-5-2023 eggs 1 egg.
13-5-2023 adult: despite 1 egg, bird incubating.
18-5-2023 nest: still 1 egg, long and blue.
27-5-2023 adult: 2x adults present. Never a chick seen in this section, or any interaction of the adult birds suggesting presence of a chick.
nest:  empty, egg gone. Hatching rate = 0. Fledging success = 0.