Larus cachinnans in the Netherlands
(last update: August 16, 2020)
Coordinators:
Albert de Jong
Leon Kelder
Roland-Jan Buijs
Thijs Horst
Merijn Loeve
Mars Muusse
Cachinnans - nest Lelystad g-M|4 (227-2025) "Blue Rope"
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 227 positioned on old Spoonbill nest, between bushes at dam 2. East of blue sign VHF20, about 25 meters: nest with the "blue rope".
- Nest 227 same for 2022-2025.
- ID certain in 2022: both immature cachinnans, one is 4CY male and one is 5CY female.
- ID certain in 2023: both are cachinnans, one is 5CY male.
- ID certain in 2024: both are cachinnans.
- ID certain in 2025: both are cachinnans. Female ringed in 2025, now g-M|4. Male seems to be a different bird from 2024.
| location | April 29th, 2022: nest with blue rope. | April 29th, 2022: nest behind bushes. | April 4th, 2023: 2 Caspian Gulls present at nest. |
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| location | April 9th, 2023: 2 Caspian Gulls present at nest. | . | . |
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| nest | April 9th, 2022: 2 eggs already. | April 29th, 2022: 2 eggs, already floating. | April 21st, 2024: full clutch, with 3 eggs. |
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| nest | April 23 2025: full clutch, 3 eggs. | . | . |
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| partner 1 | April 29th, 2022: male 4CY cachinnans. | April 29th, 2022: 4CY cachinnans. | April 29th, 2022: 4CY cachinnans. |
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| partner 1 | April 27th, 2023: 5CY cachinnans. | April 27th, 2023: 5CY cachinnans. | April 27th, 2023: 5CY cachinnans. |
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| partner 1 | April 23rd, 2024: cachinnans. | April 23rd, 2024: cachinnans. | April 23rd, 2024: cachinnans. |
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| partner 1 | April 25 2025: male Caspian Gull. | April 25 2025: male Caspian Gull. | April 25 2025: male Caspian Gull. |
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| partner 2 | May 4th, 2022: female 5CY cachinnans. | May 4th, 2022: 5CY cachinnans. | May 4th, 2022: 5CY cachinnans. |
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| partner 2 | April 23rd, 2024: cachinnans. | April 23rd, 2024: cachinnans. | April 23rd, 2024: cachinnans. |
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| partner 2 | April 25 2025: female ringed, now g-M|4. | April 25 2025: female ringed, now g-M|4. | May 08 2025: female g-M|4. |
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| pullus | May 9th, 2022: pullus r[C.P]. | November 29th, 2023: fledged r[C.P]. | May 9th, 2022: pullus r-[C.R]. |
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| pullus | May 07 2024: pullus g-B|K. | May 07 2024: pullus g-B|L. | May 07 2024: pullus g-B|M. |
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| pullus | May 13 2025: pullus g-T|T. | May 13 2025: pullus g-T|U. | October 16 2025: pullus g-R|4. Fledged. |
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Visits and data 2022.
| date: | egg no: | width (mm): | length (mm): | volume (cm3): | |
| 29-04-2022 | A | 48,2 | 69,3 | -- | float - 4 mm |
| B | 48,2 | 67,6 | -- | float - 4 mm | |
| sum nest: | -- | ||||
| 4CY is breeding. | |||||
| 04-05-2022 | 4CY at nest. | ||||
| 09-05-2022 | Loads of fish in nest. Smelly. | ||||
| 2 pulli. | |||||
| NLA 5625065 | r-C.P | ||||
| NLA 5625066 | r-C.R | Eventually, 2 chicks fledged in 2022. | |||
| egg sizes & volume 2023 | |||||||||
| SPECIES | NEST | A_length | A_width | A_volume | B_length | B_width | B_volume | TOTAL NEST: | known parents? |
| cach x cach | 227-2023 | 72,1 | 49,1 | 87,52 | 74 | 48 | 85,84 | 173,36 | same as 2022? |
| ring pulli: May 10 | laying A egg: April 5 | hatch A egg May 3 | |||||||
| 227-2023 | nest with blue rope | ||||
| dam: | dam 2 central | ||||
| location: | On Spoonbill nest, nest with blue rope, between trees. 25 mtr E of VHF20. Same nest as 2022, and likely nest 47-2021 | ||||
| breeders: | cach x cach | ||||
| OBSERVATIONS: | |||||
| 04-04-2023 | adult: | 2 cach at nest. | |||
| 09-04-2023 | nest: | 2 eggs measured. No watertest. | |||
| 26-04-2023 | nest: | 2 eggs, still. Water test: | A | 2 mm - floating | |
| B | 3 mm - floating | ||||
| 27-04-2023 | adult: | sub-adult cach breeding. | |||
| 11-05-2023 | nest: | nest looks abandoned, do they have chicks? | |||
| 13-05-2023 | adult: | parents present, pictures of partner 1. | |||
| 18-05-2023 | nest: | nest empty, no chicks found | |||
| 27-05-2023 | nest: | nest empty, no chicks found. Conclusion: nest failed in 2023. | |||
Visits and data 2024.
| NEST code | parent 1 | parent 2 | A_length | A_width | A_volume | B_length | B_width | B_volume | C_length | C_width | C_volume | TOTAL NEST: | |
| 227-2024 | cach | cach | 72,2 | 50 | 90,88 | 71,5 | 49 | 86,44 | 69,7 | 49,1 | 84,60 | 261,92 | |
| # eggs | A-egg | hatch | # ringed chicks | # all chicks | # fledged chicks | comments | |||||||
| 3 | 15-4-2024 | 13-5-2024 | |||||||||||
| dam: | dam 2 central | ||||||||||||
| location: | nest Blue Rope | ||||||||||||
| parents? | Same as 2023. | ||||||||||||
| ring pulli: | 18-May | ||||||||||||
| date | darvic | metal | location / nest# | species | sexe | age | wing | mass | head+ bill | bill | tarsus | gonys | greyscale |
| 07-05-2024 | g-B|K | .5631157 | 227 blue rope | PONT | 1CY | 76 | |||||||
| 07-05-2024 | g-B|L | .5631158 | 227 blue rope | PONT | 1CY | 94 | |||||||
| 07-05-2024 | g-B|M | .5631159 | 227 blue rope | PONT | 1CY | 79 | |||||||
| OBSERVATIONS: | |||||||||||||
| 21-04-2024 | eggs: | 3 eggs, measured. | |||||||||||
| 07-05-2024 | pullus | 3x pullus ringed. | |||||||||||
| 14-05-2024 | nest: | empty. 2x egg shells (hatched chicks). | |||||||||||
| 04-06-2024 | nest: | Empty. But 1x adult present. | |||||||||||
Visits and data 2025, Blue Rope (227) g-M|4.
| 2025 | parent 1 | parent 2 | A_length | A_width | A_volume | B_length | B_width | B_volume | C_length | C_width | C_volume | TOTAL NEST:
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# eggs | |
| g-M|4 (227) | cach | cach | 71 | 52 | 70,9 | 50,6 | 66,4 | 49,5 | 3 | |||||
| dam: | dam 2 west
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| location: | nest Blue Rope (227), 12 mtr E of Vuilnisbakkie, dam 2
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| parents: | same as 2024?
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| ringed: | ||||||||||||||
| date | darvic | metal | location / nest# | species | sexe | age | wing | mass | head+ bill | bill | tarsus | gonys | greyscale | |
| 25-04-2025 | g-M|4 | 5641005 | 227/blauwe touw | PONT | F | >4CY | 455 | 935 | 122,5 | 52,4 | 68,3 | 18,3 | ||
| 13-05-2025 | g-T|T | 5641091 | 227 | PONT | pullus | 105 | ||||||||
| 13-05-2025 | g-T|U | 5641091 | 227 | PONT | pullus | 81 | ||||||||
| 09-06-2025 | G-R|4 | 5641930 | 227/blauwe touw | PONT | pullus | 664 | ||||||||
OBSERVATIONS:
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| 23-04-2025 | eggs | 3 eggs, measured.
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| nest | Blue rope flat, between boulders, harder to see.
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| 25-04 | nest | g-M|4 female cach trapped on nest, incubating 3 eggs. Now g-M|4.
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| 01-05 | chicks | 2x wet chick, 1x egg
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| adult | 2x Caspian present
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| 08-05 | adult | both partners present
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| 13-05 | chicks | 2 chicks ringed, 1 egg hatching
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| 09-06 | chicks | 1 chick found and ringed. Eventually: g-R|4 fledged, while g-T|T & g-T|U not seen after ringing.
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