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 - nest Lelystad 058
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 058 on breakwater dam 1 south section, 'nest with buoy', behind willow, easternmost cachinnans nest in south section. Easy to trap the adults here in future (season 2022?).
- ID uncertain in 2021, one is 4CY-type and match pure Caspian Gull cachinnans. Other is 5CY uncertain cachinnans, with "hybrid type" P10 pattern and bill shape rather bulbous.
- ID uncertain in 2022, one is 5CY Caspian Gull cachinnans. Other is unknown.
| location | April 24th, 2021. | April 24th, 2021. | April 24th, 2021. |
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| eggs | May 13th, 2021: A egg hatching. | May 13th, 2021: A & B chicks hatched. | May 4th, 2022: 2 eggs. |
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| partner 1 | April 26th, 2021: moulting cachinnans parent, "4CY". | April 26th, 2021: moulting cachinnans parent, "4CY". | April 26th, 2021: moulting cachinnans parent, "4CY". |
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| partner 1 | April 11th, 2022: cachinnans 5CY. | April 11th, 2022: cachinnans 5CY. | May 17th, 2022: cachinnans 5CY. |
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| partner 2 | May 13th, 2021: 5CY, P10 tongue without angle. | May 13th, 2021: 5CY, P10 tongue without angle. | May 13th, 2021: 5CY. |
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| pulli | May 28th, 2021: cachinnans pulli b[F|V] and b[F|W]. | May 17th, 2022: hick r[5.F]. | . |
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| prey | May 17th, 2022: Carp and Rudd. | . | . |
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Visits and data 2021:
| date: | ||||||
| 24-04-2021 | One partner is sub-adult. Nest allows trapping breeders, easily. 3 eggs in nest. | |||||
| egg no: | width (mm) | length (mm) | volume (cm3): | water test on April 24th: | ||
| A egg | 46,2 | 75,3 | 80,92 | 60 - tip bottom | ||
| B egg | 48,3 | 73,7 | 86,57 | 35 - tip bottom | ||
| C egg | 48,9 | 72,9 | 87,77 | 25 - tip bottom | ||
| sum nest: | 255,26 | |||||
| 26-04-2021 | Breeding bird is moulting sub-adult (4CY). Also 5CY present on bread, but really bird of nest 58? | |||||
| 13-05-2021 | Partner 2 is 5CY bird! 4CY also patrolling over nest. 5CY bird chasing neighbour Lesser Black-backeds. | |||||
| 3 eggs just hatching. | ||||||
| 15-05-2021 | C egg with small cracks, will hatch soon. | |||||
| 1 hatched chick, still wet, hatched this morning. | ||||||
| 1 hatched chick (1 day old). Mass = 66 gr. | ||||||
| 28-05-2021 | metal | tibia | mass | head + bill | ||
| pull | .5559407 | b-F|V | >400 | 82,8 | ||
| pull | .5559408 | b-F|W | >400 | 84,4 | ||
| 08-06-2021 | 2 partners at nest. Chasing neighbouring Lesser Black-backeds. | |||||
| 26-06-2021 | No activity. | |||||
| Visits and data nest 58-2022: Estimation egg laying: A-egg = April 11 2022. Estimating hatching = May 09 2022. |
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| 11-04-2022 | 1 egg in nest | |||||
| 15-04-2022 | egg no: | width (mm) | length (mm) | volume (cm3): | water test: | |
| A egg | 49,6 | 71,3 | -- | not necessary. | ||
| B egg | 50 | 66,3 | -- | |||
| 19-04-2022 | 5CY cachinnans at nest. | |||||
| 04-05-2022 | 2 eggs | |||||
| 09-05-2022 | 1 pullus, hatched this morning, exactly as scheduled. 2nd egg disappeared (predated?). | |||||
| 17-05-2022 | metal | tibia | mass | head + bill | ||
| pull | .5625105 | r-5F | 231 | -- | ||
| prey: many small Carp and probably Rudd. | ||||||
| 22-05-2022 | 5CY cachinnans at nest. | |||||
| 17-07-2022 | r-5F picture, fledged. | |||||