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 019
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 019 positioned high on artificial breakwater dam 1, 20 meters west of y-PNED. Nest in dense complex of Blackberry vegetation, with cluster with Spoonbills.
- Nest marked with red flag. Location is close to nest 36-2020. Subsequent years: nest 19-2022 and 19-2023 at exact same spot on dam 1.
- ID in 2021 certain: both partners are Caspian Gull cachinnans.
- ID in 2022 certain: both partners are Caspian Gull cachinnans, likely same as in 2021.
- ID in 2023 uncertain: one partner is Caspian Gull cachinnans, female might be Herring Gull argenteus. Supported by plumage of juvenile g-8|U with Herring traits.
| location | Nest between Spoonbills, April 26, 2021. | April 19th, 2022: nest location. | June 8th, 2021: partners & 2 chicks at blocks. |
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| April 26th, 2023: nest location. | April 26th, 2023: nest location. | April 26th, 2023: nest location. | |
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| eggs | Eggs April 16th, 2021: 3 eggs clutch. | April 27th, 2022: 3 eggs. | April 26th, 2023: 1 egg. |
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| partner 1 | June 8th, 2021: partner 1 = male cachinnans. | June 8th, 2021: partner 1 = male cachinnans. | June 8th, 2021: partner 1 = male cachinnans. |
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| April 27th, 2022: partner 1 = male cachinnans. | May 1st, 2022: partner 1 = male cachinnans. | May 4th, 2022: partner 1 = male cachinnans. | |
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| partner 2 | April 26th, 2021: female in Blackberry complex. | June 8th, 2021: partner 2 = female cachinnans. | June 8th, 2021: partner 2 = female cachinnans. |
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| April 27th, 2022: partner 2 = female cachinnans. | April 27th, 2022: partner 2 = female cachinnans. | April 27th, 2022: breeding female cachinnans. | |
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| partner? | On May 6th, 2021, we assumed this to be one of the partners: male Caspian Gull cachinnans. Note different P5 pattern. | . | . |
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| pullus | May 9th, 2022: pullus r[5.U]. | May 9th, 2022: pullus r[5.V]. | |
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| June 18th, 2023: g[8|S]. Head wound. | June 18th, 2023: g[8|T]. Checked upon by Herring. | July 8th, 2023: g[8|U]. | |
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Visits and data.
| date: | |||||||
| egg no: | width (mm): | length (mm): | volume (cm3): | water test on April 16th: | laying date: | ||
| 16-04-2021 | A | 48,4 | 70,9 | 83,63 | 30 - tip bottom | 3 eggs in nest. | |
| 16-04-2021 | B | 50,5 | 70,8 | 90,91 | 50 - tip bottom | ||
| 16-04-2021 | C | 49,4 | 68,8 | 84,54 | 55 - tip bottom | ||
| sum nest: | 259,07 | ||||||
| 26-04-2021 | 1 parent present at nest, between Spoonbills. | ||||||
| 13-05-2021 | No visit, Camilla is catching a Spoonbill. | ||||||
| 06-05-2021 | Picture of one partner: male cachinnans. | ||||||
| 15-05-2021 | No visit, thunder coming in. | ||||||
| 28-05-2021 | No visit. | ||||||
| 08-06-2021 | 2 large pulli & 2 parents on the blocks near the waterfront at north side. Next time, easy to trap. | ||||||
Visits and data 2022 for nest 19:
Estimation egg laying: A-egg = April 03 2022. Estimating hatching = May 01 2022.
| date: | |||||||
| egg no: | width (mm): | length (mm): | volume (cm3): | ||||
| 15-04-2022 | A | 49,8 | 68,3 | -- | 90 - tip bottom | 3 eggs | |
| B | 50,4 | 69 | -- | 90 - tip bottom | |||
| C | 48,2 | 68,1 | -- | 90 - tip bottom | |||
| sum nest: | -- | ||||||
| 19-04-2022 | 3 birds present: including female w-327:U without nest. | ||||||
| 27-04-2022 | A | -- | -- | -- | 3 mm - floating | 3 eggs | |
| B | -- | -- | -- | 3 mm - floating | |||
| C | -- | -- | -- | 4 mm - floating | |||
| parent 1 = cachinnans. | |||||||
| 01-05-2022 | 2 parents at nest. | ||||||
| 04-05-2022 | male = cachinnans. | ||||||
| 09-05-2022 | Nest is empty, no chicks found, but much shit; the chicks hide in Blackberry complex. | ||||||
| metal | darvic | mass | H+B | ||||
| 17-05-2022 | pullus | 5.625.119 | r-5V | 404 | 80,5 | ||
| pullus | 5.625.120 | r-5U | 464 | 82,5 | |||
| 17-06-2022 | No birds present. | ||||||
| 21-06-2022 | No activity at nest. | ||||||
| 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 | 19-2023 | 74,6 | 53,1 | 105,91 | 0 | 0 | 0,00 | 0 | 0 | 0,00 | 105,91 | new birds |
| ring pulli: 27-05-2023 | laying A egg: 26-04-2023 | hatch A egg: 24-05-2023 | ||||||||||
| catch: | date: | metal: | darvic: | mass: | wing: | head+bill: | ||||||
| Pullus | 27-05-2023 | 5.625.263 | g-8|T | 160 | -- | -- | ||||||
| Pullus | 27-05-2023 | 5.625.265 | g-8|U | 80 | -- | -- | ||||||
| Pullus | 27-05-2023 | 5.625.267 | g-8|S | 125 | -- | -- | ||||||
| Pullus | 18-06-2023 | 5.625.265 | g-8|U | -- | -- | -- | ||||||
| Pullus | 18-06-2023 | 5.625.263 | g-8|T | 765 | 205 | 103,6 | Herring type. With HG parent (?) later this date. | |||||
| Pullus | 18-06-2023 | 5.625.267 | g-8|S | -- | -- | -- | Bleeding head wound, not measured. | |||||
| Pullus | 25-06-2023 | 5.625.265 | g-8|U | 847 | 241 | 109 | ||||||
| 19-2023 | ||
| dam: | dam 1 east | |
| location: | Low on N-side of dam. In blackberry complex. Location is nest 19-2020/22, old code still readable. | |
| breeders: | cach x teus | |
| OBSERVATIONS: | ||
| 09-04-2023 | adult: | 2 unringed cach present at blocks on N side, in front of location. Search for nest today. |
| 26-04-2023 | nest: | same location, old codes still present. Refreshed with spray. |
| eggs: | 1x egg, egg is cold. Nest abandoned? Egg measured. | |
| comment: | This used to be an early nest, 3 eggs should be floating already this date. In retrospect: late, as one parent is now Herring Gull? | |
| 13-05-2023 | adult: | partner 1 = cach adult. |
| 18-05-2023 | nest: | 3 eggs. |
| 27-05-2023 | pulli: | 3x chicks ringed and measured. |
| 18-06-2023 | pulli: | 3x chicks present, but not in category 'fledged', still too young. |
| pullus: | g-8|S with terrible head wound, therefore not measured. Will probably not survive. | |
| pullus: | g-8|T between blocks, was checked upon by adult Herring Gull, close to nest site. Hence: at least one parent is Herring!? | |
| 25-06-2023 | pullus: | g-8|U caught and measured. |