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
Cachinnans - nest g-A|E & g-M|+
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).
- Location is nest r-CG (y-PHSV, from Poland). Until 2024 r-CG loyal to site, dam 1 south section, only visible from N side. In Blackberry bush, under Willow.
- In 2025: r-CG present at nest site once. Some days in colony, with r-6X but no breeding at Lelystad.
- Instead, nest occupied by same adult male (ex-partner r-CG 2024), this year ringed g-M|+. female is ex-partner of y-PAMO, ringed in 2024 as g-A|E.
| location | April 12 2024: nest r-CG. 1 egg, behind tree. | April 21 2024: nest r-CG. 3 eggs clutch. | April 21 2025: 3 eggs (full clutch). |
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| partner 1 | May 02 2024: unringed male (partner r-CG). | May 02 2024: unringed male (partner r-CG). | May 02 2024: unringed male (partner r-CG). |
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| partner 1 | April 28 2025: male Caspian Gull, now g-M|+. | April 28 2025: male Caspian Gull g-M|+. | April 28 2025: male Caspian Gull g-M|+. |
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| partner 2 | March 19 2024: y[P:AM0] & female (later g-A|E) | April 26 2024: unringed partner now g-A|E. | July 09 2025: female Caspian Gull g-A|E. |
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| pullus | June 09 2025: chick g-N|X. Fledged. | November 09 2025: chick g-N|Y. Fledged. | June 09 2025: chick g-N|Z. Fledged. |
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Visits and data 2025 for nest g-A|E & g-M|+.
| 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-A|E | cach | cach | 73,4 | 48,5 | 70 | 49,7 | 69,2 | 50 | 3 | ||||
| dam: | dam 1 centraal | ||||||||||||
| location: | dam 1, was nest r-CG 2024, under tree.
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| parents: | in 2025: ex male r-CG 2024, female is g-A|E (female partner of PAM0 in 2024).
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| ringed: | |||||||||||||
| date | darvic | metal | location / nest# | species | sexe | age | wing | mass | head+ bill | bill | tarsus | gonys | |
| 28-04-2025 | g-M|+ | 6254496 | nest g-A|E | PONT | M | >4CY | 470 | 1260 | 140,7 | 64,4 | 78,1 | 20,1 | |
| 13-05 | g-N|X | 5641026 | g-A|E & g-M|+ | PONT | pullus | 218 | |||||||
| 13-05 | g-N|Y | 5641027 | g-A|E & g-M|+ | PONT | pullus | 191 | |||||||
| 13-05 | g-N|Z | 5641028 | g-A|E & g-M|+ | PONT | pullus | 240 | |||||||
| 09-06 | G-N|X | 5641026 | PONT | pullus | 850 | CONTROL | |||||||
| 09-06 | G-N|Y | 5641027 | PONT | pullus | 950 | CONTROL | |||||||
| OBSERVATIONS: | |||||||||||||
| 10-04-2025 | parents: | at nest: g-A|E female cachinnans. Also unringed cachinnans, which was male partner of r-CG in 2024 at this location.
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| Where is cachinnans r-CG which was the female at this nest over the last years? Observed with few new male partners, with hybrid r-6X lately. | |||||||||||||
| Conclusion: male of r-CG (in 2024) remained at nest location, now bonding with g-A|E, ex-female of y-P:AM0 (2024). R-CG is alive and searching. | |||||||||||||
| 21-04 | nest: | measured 3 eggs.
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| adult: | unringed male attacks.
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| 23-04 | adult: | attempt to trap unringed male. Failed.
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| 28-04 | adult: | trapped adult male cachinnans, now g-M|+. Pictures compared: is male 2024 in this nest.
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| 13-05 | pullus | 3x pullus ringed.
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| 09-06 | chicks | 3x pullus on water, 2 caught and measured, 3rd escaped.
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