Larus cachinnans in the Netherlands
(last update: August 16, 2020)
Albert de Jong
Merijn Loeve
Roland-Jan Buijs
Leon Kelder
Mars Muusse
Cachinnans - nest Lelystad 061 tibia r[F.B]
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 marked with code "61" on tarmac dam.
- Nest 061 "r-F.B" on breakwater dam 1 south section, most western cachinnans nest. Easy to trap the adults here; female trapped in 2021 and ringed r-F.B.
- ID certain in 2021, both breeders are Caspian Gull cachinnans. Male is aged "5CY", on pattern of primary coverts.
| location | April 24th, 2021: red spray "61". | April 24th, 2021: red spray "61". | April 26th, 2021: guarding male, breeding female. |
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| May 13th, 2021: female guarding, male in nest. | . | . | |
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| eggs | April 24th, 2021: 2 eggs in nest. | April 24th, 2021. | May 13th, 2021: 3 eggs in nest. |
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| partner 1 | April 26th, 2021: male cachinnans 5CY. | April 26th, 2021: male cachinnans 5CY. | May 13th, 2021: male cachinnans. |
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| partner 2 | May 13th, 2021: female cachinnans. | May 13th, 2021: female cachinnans. | May 13th, 2021: female cachinnans. |
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| May 28th, 2021: Roland-Jan Buijs & Mars Muusse. | May 28th, 2021: Roland-Jan Buijs & Albert de Jong. | May 28th, 2021: female cachinnans r-F.B. | |
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| May 28th, 2021: female cachinnans r-F.B. | May 28th, 2021: female cachinnans r-F.B. | May 28th, 2021: female cachinnans r-F.B. | |
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| May 28th, 2021: female cachinnans r-F.B. | May 28th, 2021: female cachinnans r-F.B. | . | |
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| pullus | May 28th, 2021: cachinnans pullus r[F.Y]. | . | . |
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Visits and data.
| date: | ||||||||
| 24-04-2021 | 2 partners present, both cachinnans. Nest allows trapping breeders, easily. | |||||||
| 2 eggs in nest. | ||||||||
| egg no: | width (mm) | length (mm) | volume (cm3): | water test on April 24th: | ||||
| A egg | 50,8 | 71,8 | 93,29 | 30 - tip bottom | ||||
| B egg | 49,7 | 70,4 | 87,56 | 25 - tip bottom | ||||
| sum nest: | -- | |||||||
| 26-04-2021 | Both partners present, one guarding, one breeding. A female cachinnans with hanging left leg in flight is most probably NOT the breeding female. Is another cachinnans breeding here as well? | |||||||
| 13-05-2021 | Both partners present. Male has 5CY markings. Now the right female photographed in flight. | |||||||
| 3 eggs in nest. | ||||||||
| 15-05-2021 | 3 eggs in nest. | |||||||
| 28-05-2021 | 3 eggs in nest. | |||||||
| Cage placed and one bird (female) trapped for ringing. | ||||||||
| metal | tibia | mass | head + bill | wing | tarsus | bill | ||
| adult | .5559427 | r-F.B | 1030 | 124 | 454 | 69,7 | 59,8 | |
| 08-06-2021 | Both partners present. At least 2 chicks around. | |||||||
| metal | tibia | mass | head + bill | wing | ||||
| 26-06-2021 | pullus | .5550695 | r-F.Y | 649 | 90,4 | 157 | most likely cachinnans chick of nest 61. | |
| pullus | .5550696 | r-F.Z | 1126 | 111,8 | 260 | argentatus, near nest 61, from neighbouring nest. | ||
| pullus | .5550697 | r-F.1 | 1036 | 108,6 | 269 | argentatus, near nest 61, from neighbouring nest. | ||
| pullus | .5550698 | r-F.2 | 879 | 98,4 | 230 | argentatus, near nest 61, from neighbouring nest. | ||