Larus cachinnans in the Netherlands
(last update: August 16, 2020)
Albert de Jong
Leon Kelder
Roland-Jan Buijs
Thijs Horst
Merijn Loeve
Mars Muusse
Cachinnans - nest Lelystad "Vuilnisbakkie" (252), g-A|D in 2024, g-M|1 in 2025
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 252 positioned on dam 2 central section: 2 mtr W of nest 18 "nest with blue rope", on S-side of dam 2. Black plastic sprayed with white + sign, nicknamed "vuilnisbakkie".
- ID certain in 2023: both parents are cachinnans, male is sub-adult.
- ID certain in 2024: both parents are same cachinnans as in 2023. Female cachinnans trapped in April 2024, now g-A|D.
- ID certain in 2025: both parents are cachinnans, but female g-A|D not present. New female cachinnans trapped in 2025, now g-M|1.
| location | April 9th, 2023: nest location dam 2. | May 13th, 2023: Caspian parents. | April 21st, 2024: nest location |
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| nest | April 26th, 2023: full clutch, with 3 eggs. | April 21st, 2024: full clutch, with 3 eggs. | April 30 2024: location. |
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| nest | April 12 2025: location. | April 21 2025: nest with 3 eggs. | April 25 2025: nest Vuilnisbakkie. |
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| partner 1 | April 27th, 2023: sub-adult male cachinnans. | April 27th, 2023: sub-adult male cachinnans. | April 27th, 2023: sub-adult male cachinnans. |
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| partner 1 | April 23rd, 2024: adult male cachinnans. | April 23rd, 2024: adult male cachinnans. | April 23rd, 2024: adult male cachinnans. |
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| partner 1 | April 30th, 2024: male cachinnans. | April 30th, 2024: male cachinnans. | April 30th, 2024: male cachinnans. |
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| partner 1 | April 25 2025: adult male cachinnans. | April 25 2025: adult male cachinnans. | April 4th, 2025: adult male cachinnans. |
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| partner 2 | April 27th, 2023: adult female cachinnans. | April 27th, 2023: adult female cachinnans. | April 27th, 2023: adult female cachinnans. |
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| partner 2 | April 23rd, 2024: adult female cachinnans. | April 23rd, 2024: adult female cachinnans. | April 23rd, 2024: adult female cachinnans. |
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| partner 2 | April 26, 2024: trapped female cachinnans, now g-A|D. | April 26, 2024: trapped female cachinnans, now g-A|D. | April 26, 2024: trapped female cachinnans, now g-A|D. |
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| partner 2 | April 1st, 2025: adult female cachinnans, not g-A|D. | April 23 2025: trapped female cachinnans, now g-M|1. | April 23 2025: trapped female cachinnans, now g-M|1. |
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| partner 2 | April 23 2025: trapped female cachinnans, now g-M|1. | April 23 2025: trapped female cachinnans, now g-M|1. | April 23 2025: trapped female cachinnans, now g-M|1. |
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| chicks | May 11th, 2023: pullus r[7.9]. | May 11th, 2023: pullus r[7.+]. | July 8th, 2023: fledged g[8|8]. |
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| chicks | July 11 2025: fledged g[T|V]. | . | . |
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Data for nest 252-2023:
| 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: |
| cach x cach | 252-2023 | 73,5 | 48,1 | 85,62 | 74 | 49,2 | 90,19 | 70,5 | 49 | 85,23 | 261,04 |
| ring pulli: May 12 | laying A egg: April 07 | hatch A egg: May 05 | |||||||||
| catch: | date: | metal: | darvic: | ||||||||
| pullus | 11-5-2023 | 5.556.457 | r-7.9 | few days old | |||||||
| pullus | 11-5-2023 | 5.556.458 | r-7.+ | few days old | |||||||
| pullus | 18-5-2023 | mass: | head+bill: | nothing present | |||||||
| pullus | 27-5-2023 | 5.625.262 | g-8|8 | 577 | 262 | ||||||
| 252-2023 | Nest "dustbin" (Vuilnisbakkie) | ||
| dam: | dam 2 central | ||
| location: | 2 mtr W of nest 18 "nest with blue rope". Black plastic sprayed with white + sign. | ||
| breeders: | cach x cach | ||
| OBSERVATIONS: | |||
| 09-04-2023 | nest: | 2 eggs measured. No watertest. | |
| 26-04-2023 | nest: | 3 eggs. Measured. | |
| 27-04-2023 | adult: | adult female cach & 5/6CY male cach | |
| 11-05-2023 | pulli: | 2 chicks ringed, other chick? | |
| 13-05-2023 | adult: | ||
| 18-05-2023 | pulli: | Nest empty, no chicks found | |
| 27-05-2023 | pulli: | 1x extra pullus ringed and measured. | |
| 25-06-2023 | pulli: | G-8|8 present. At least 1 bird fledged. | |
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: | |
| 252-2024 | cach | cach | 79 | 48,3 | 92,79 | 75 | 48,5 | 88,83 | 72 | 48 | 83,52 | 265,15 | |
| # eggs | A-egg | hatch | # ringed chicks | # all chicks | # fledged chicks | comments | |||||||
| 3 | 15-4-2024 | 13-5-2024 | |||||||||||
| dam: | dam 2 west | ||||||||||||
| location: | nest thrash can "Vuilnisbakkie", is same as 2023 | ||||||||||||
| parents? | Same as 2023. | ||||||||||||
| ring pulli: | 18-May | ||||||||||||
| date | darvic | metal | location / nest# | species | sexe | age | wing | mass | head+ bill | bill | tarsus | gonys | greyscale | 26-04-2024 | g-A|D | .5625298 | Vuilnisbakkie | PONT | F | >4CY | 436 | 125,0 | 55,6 | 69,5 | 19,0 | 5 |
| OBSERVATIONS: | |||||||||||||
| 21-04-2024 | eggs: | 3 eggs, measured. | |||||||||||
| 26-04-2024 | adult: | adult female trapped at nest, now g-A|D. | |||||||||||
| 07-05-2024 | eggs: | 3x, of which 1x hatching. | |||||||||||
| 14-05-2024 | nest: | Empty. Search for chicks quickly stopped (fragile nest). No ringed. Will ring when large. | |||||||||||
| 04-06-2024 | nest: | Empty and no activity. No adults in territory. | |||||||||||
Visits and data 2025, 'vuilnisbakkie' (252) g-M|1.
| 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|1 (252) | cach | cach | 73,7 | 49 | 73,4 | 48,6 | 73 | 49,8 | 3 | |||||
| dam: | dam 2 west
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| location: | Vuilnisbakkie (nest 252), was nest g-A|D in 2024, but g-A|D not seen in 2025
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| ouders: | new female cachinnans, not g-A|D. Trapped this year, now g-M|1. Male is same as 2024, unringed.
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| ringed: | ||||||||||||||
| date | darvic | metal | location / nest# | species | sexe | age | wing | mass | head+ bill | bill | tarsus | gonys | greyscale | |
| 23-04-2025 | g-M|1 | 5641002 | nest Vuilinisbakkie | cach | F | >4CY | 454 | 887 | 124 | 54,8 | 68,4 | 17,4 | 6 | |
| 13-05-2025 | g-T|V | 5641094 | 252 | PONT | pullus | 302 | ||||||||
| 09-06-2025 | g-T|V | 5641094
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PONT | pullus | 673 | CONTROL | ||||||||
OBSERVATIONS:
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| 01-04-2025 | nest | cach breeding, Not g-A|D, but unringed female
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| 12-04 | nest | flying adult
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| 21-04 | nest | Now several spoonbills surrounding this nest
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| 21-04 | adult | 2x caspian gulls at nest, 1 is incubating. Attempt to trap a breeding bird, failed.
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| 23-04 | eggs | 3 eggs | ||||||||||||
| 23-04 | adult | trapped female, now g-M|1, incubating 3 eggs at nest Vuilnisbakkie
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| 01-05 | chicks | 2x wet chicks, 1x egg
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| 08-05-2025 | adult | both partners present and 1 chick
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| 13-05-2025 | chicks | 1 chick ringed, 2 chicks dead stuck between rocks.
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| 09-06-2025 | chicks | g-T|V found and measured. This chick fledged.
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