Larus cachinnans in the Netherlands
(last update: August 16, 2020)
Albert de Jong
Merijn Loeve
Roland-Jan Buijs
Thijs Horst
Leon Kelder
Mars Muusse
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.
- ID in 2024 certain, same male and female cachinnans. Note P10 patterns of partner 2.
| 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". |
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| April 26th, 2023: 1 egg. | April 26th, 2023: 1 egg. | April 26th, 2023: 1 egg. | |
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| partner 1 | April 24th, 2021: partner 1 = cachinnans. | April 24th, 2021: partner 1 = cachinnans. | April 29th, 2022: cachinnans partners. |
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| partner 1 | April 29th, 2022: partner 1 = cachinnans (same as 2021). | May 13th, 2023: partner 1 = cachinnans. | May 13th, 2023: partner 1 = cachinnans. |
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| partner 1 | May 13th, 2023: partner 1 = cachinnans. | April 23 2024: partner 1 (cachinnans) as 2023. | April 23 2024: partner 1 (cachinnans) as 2023. |
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| partner 2 | April 24th, 2021: partner 2 = cachinnans. | April 24th, 2021: partner 2 = cachinnans. | April 24th, 2021: partner 2 = cachinnans. |
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| partner 2 | April 29th, 2022: partner 2 = cachinnans (same as 2021). | April 29th, 2022: partner 2 = cachinnans. | mat 4th, 2022: partner 2 = cachinnans. |
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| partner 2 | May 13th, 2023: partner 2 = cachinnans. | May 13th, 2023: partner 2 = cachinnans. | . |
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| . | April 23 2024: partner same as 2023. | April 23 2024: partner same as 2023. | April 23 2024: partner same as 2023. |
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| 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). |
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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. | |
Visits and data 2024.
| NEST code | parent 1 | parent 2 | # eggs | ||||||||||
| 046-2024 | cach | cach | 0 | ||||||||||
| dam: | dam 2 east | ||||||||||||
| location: | nest 'red corner-flag', on blocks-east, no eggs in 2022, 2023, 2024 | ||||||||||||
| parents? | same as 2022, 2023 | ||||||||||||
| OBSERVATIONS: | |||||||||||||
| 12-04-2024 | eggs: | 0x, nest empty but ready. |
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| food: | Perch, 17 cm. | ||||||||||||
| 21-04-2024 | eggs: | 0x. | |||||||||||
| 14-05-2024 | eggs: | 0x. | |||||||||||