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 hybrid - nest Lelystad y-X71A
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 y-X71A positioned in section dam 1 south. Nest at edge of Blackberry complex, at transition to tarmac dam, about 25 meters west of nest n-F|N.
In 2023 approx at same location. - ID uncertain in 2022, one partner is male hybrid cachinnans y-X71A. Partner most likely Herring Gull.
- ID uncertain in 2023, one partner is male hybrid cachinnans y-X71A. Partner is Herring Gull.
| location | May 4th, 2022: 3 eggs at nest. | May 4th, 2022: nest location. | May 4th, 2022: y-X71A at nest. |
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| partner 1 | May 4th, 2022: y-X71A at nest. | May 4th, 2022: y-X71A at nest. | May 1st, 2022: y-X71A with possible Herring Gull partner. |
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| April 11th, 2022: male is hybrid Caspian Gull y-X71A. | April 15th, 2022: male is hybrid Caspian Gull y-X71A. | April 27th, 2022: male is hybrid Caspian Gull y-X71A. | |
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| April 27th, 2023: 6CY male is hybrid Caspian Gull y-X71A. | April 9th, 2023: 6CY male is hybrid Caspian Gull y-X71A. | . | |
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| partner 2 | April 09 2023: partner is female Herring Gull. | April 09 2023: partner is female Herring Gull. | . |
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| food | May 30th, 2022: food is Eel. | . | . |
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Visits and data:
Estimation egg laying: A-egg = April 26 2022. Estimating hatching = May 24 2022.
| date | |||||||
| 27-04-2022 | Again, y-X71A standing high on dam, guarding the area. | ||||||
| Nest located here with 1 egg. Label: nest 119Z (part of control group Herring Gulls). | |||||||
| 1 egg | egg no: | width (mm) | length (mm) | volume (cm3): | water test on April 27th: | ||
| A egg | 51,2 | 71,2 | -- | 00 - tip on bottom | |||
| 01-05-2022 | y-X71A standing high on dam, about 25 meters from nest 61, near 119Z. y-X71A classified as male cachinnans hybrid.. | ||||||
| 04-05-2022 | y-X71A steps from nest, was breeding. Code 119Z sprayed near nest. | ||||||
| 3 eggs | egg no: | width (mm) | length (mm) | volume (cm3): | water test on May 4th: | ||
| A egg | 51,2 | 71,3 | -- | -- | |||
| B egg | 47,7 | 68,8 | -- | -- | |||
| C egg | 47,5 | 65,8 | -- | -- | |||
| 09-05-2022 | 3 eggs. | ||||||
| 17-05-2022 | 3 eggs. | ||||||
| 22-05-2022 | 3 eggs. First crack in shell. Decided not to try to trap adult at nest. y-X71A present. | ||||||
| 30-05-2022 | 1 chick present: chick r-5+ (which belongs to nest 117Z). No chicks of nest 119Z found in vegetation. | ||||||
| food: large Eel (25 cm's) next to nest. No sign of adults. | |||||||
| In 2022 no chicks ringed in this nest and no data on fledging. | |||||||
| 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? |
| hybrid x teus | X71A | 73,4 | 51 | 96,12 | 73,2 | 50,8 | 95,11 | 70,8 | 48,4 | 83,51 | 274,74 | same as 2022 |
| ring pulli: 20-mei | laying A egg: -- | hatch A egg: -- | ||||||||||
| X71A | 122-2023 | |
| dam: | dam 1 west | |
| location: | Coded 122 on tarmac, nest is next to sprayed white spot | |
| breeders: | hybrid x teus | |
| OBSERVATIONS: | ||
| 05-04-2023 | adult: | yX71A present. |
| 09-04-2023 | nest: | seems ready. |
| adult: | Male is yX71A, female is teus. Guarding on top of dam. | |
| 22-04-2023 | nest: | 3 eggs, watertest: tip at bottom 70, 50, 20 degrees respectively. |
| 27-04-2023 | adult: | Male is yX71A, female is argenteus. Guarding on top of dam. |
| 03-05-2023 | adult: | Cage on nest 119 border tarmac-vegetation (was location 119-2022). Now trapped a LBBG here. |
| X71A moved to location 122-2022? In retrospect: yes. | ||
| 25-06-2023 | adult: | X71A present on dam, unknown if he has any chicks. |