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 x argenteus - nest Lelystad 006
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 006 positioned on artificial breakwater 1 at T-split. Location is nest PLDP - 2020 (in 2021, PLDP moved to nest PESV).
In 2023 location used by mixed pair Caspian Gull & Herring Gull. - Certainty on ID in 2021, breeders are male Caspian Gull cachinnans and female Herring Gull argenteus.
- Certainty on ID in 2023, breeders are male Caspian Gull cachinnans and female Herring Gull argenteus.
| location | April 16th, 2021: male cach & female teus. | May 6th, 2021: male cach & female teus. | April 16th, 2021: male cach & female teus. |
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| April 27th, 2023. Caspian x Herring nest. | April 27th, 2023. Caspian x Herring nest. | . | |
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| April 27th, 2023. Caspian "almost thayeri P10". | April 27th, 2023. Caspian "almost thayeri P10". | April 27th, 2023. Caspian "almost thayeri P10". | |
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| pulli | May 28th, 2021: pullus, likely wrong nest. | June 8th, 2021: too many cachinnans! | . |
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Visits and data.
| date: | ||||||
| 16-04-2021 | Two adult at nest, photographed. Nest without eggs. Many Spoonbills breeding here, hampering visits in future. | |||||
| 24-04-2021 | Correction on flag code. Now labeled "6". Nest abandoned, no eggs? | |||||
| 26-04-2021 | No visit, Camilla is trapping a Spoonbill. | |||||
| 06-05-2021 | egg no: | width (mm) | length (mm) | volume (cm3): | water test on May 6th: | 3 eggs in nest |
| A egg | 49,2 | 68,7 | 83,73 | 25 - tip at bottom | ||
| B egg | 50,7 | 71,7 | 92,80 | 30 - tip at bottom | ||
| C egg | 51,9 | 71,5 | 96,97 | 55 - tip at bottom | ||
| sum nest: | 273,50 | |||||
| 15-05-2021 | 2 eggs in nest. Nest located at 'the flat stone' in dense, inaccessible Blackberry complex. | |||||
| 28-05-2021 | metal | tibia | mass (gr) | head + bill (mm) | ||
| pullus | .5559419 | -- | -- | -- | Chick is 1 day old. Only metal ringed. No certianty about species. | |
| 1 egg: just hatching. | ||||||
| In retrospect: this nest was situated 'too high' at dam 1, likely different nest. Hybrid nest is situated at flat stone, lower and central at dam (see May 15th). | ||||||
| 08-06-2021 | Sitiuation not clear: several cachinnans and argenteus here guarding 3 large chicks. Favorite place for chicks at the blocks near waterfront, below Blackberry complex. | |||||
| 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 teus | 6-2023 | 71,2 | 49,7 | 88,55 | 69,7 | 49,2 | 84,95 | 69,7 | 47,4 | 78,85 | 252,35 | New nest. |
| 6-2023 | OLD LOCATION PESV | |
| dam: | dam 1 T-split | |
| location: | old nest yPESV, N of Elder bush (Vlierstruik), visible from West. | |
| breeders: | cach x teus | |
| OBSERVATIONS: | ||
| 09-04-2023 | 1 adult | Guarding cach type with yellow legs. |
| 27-04-2023 | adult: | 1x teus and 1x cach at nest location. Quickly returning. Should check for nest here. |
| Check cach from pictures 2022: this is a known bird (the 'almost thayeri'.)… | ||
| 13-05-2023 | adult: | again, the cach with limpy left leg. |
| 27-05-2023 | nest: | 3 eggs measured. |