Larus cachinnans in the Netherlands
(last update: August 16, 2020)
Albert de Jong
Leon Kelder
Roland-Jan Buijs
Thijs Horst
Merijn Loeve
Mars Muusse
Cachinnans - nest Lelystad g-N|D & g-N|F (034-2025)
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 034 positioned at breakwater 1, called "branch-nest" (3 white stripes on dead branch), between y[PNED] and T-split. Two meters from nest 33.
- In 2024: nest "rode flap": at blocks, just west of open tarmac, was 'nest with the branch 2022', now with red flag and black root-cloth.
- In 2025 again nest "Rood Flapje".
- ID in 2020 certain, male is Caspian Gull cachinnans, female is Herring Gull argenteus.
- ID in 2021 certain, same pair in 2021.
- ID in 2022 certain, same pair in 2022.
- ID in 2023 certain, same pair in 2023.
- ID in 2024 certain, male and female are Caspian Gull cachinnans.
- ID in 2025 certain, Caspian Gull cachinnans, in 2025 male is g-N|D and female is g-N|F. First egg on April 4th, 2025.
| location | May 7th, 2020: nest location - stripes on branch. | March 23rd, 2021: nest location - stripes on branch. | March 27th, 2022: nest location - stripes on branch, coded 130. |
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| location | April 21st, 2024: Caspian breeding at "Roodflapje". | April 21st, 2024: 3 eggs clutch: "Roodflapje". | April 28th, 2025: nest location, nest Blue Bucket behind it. |
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| nest | May 7th, 2020: 3 eggs. | March 27th, 2022: 3 eggs. | April 12th, 2024: 3 eggs clutch: "Roodflapje". |
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| nest | April 23 2025: 3 eggs. | April 23 2025: 3 eggs. | . |
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| partner 1 | May 7th, 2020: female argenteus. | May 7th, 2020: female argenteus x male cachinnans. | March 23rd, 2021: female argenteus. |
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| partner 1 | April 28 2025: female Caspian Gull g-N|F. | April 28 2025: female Caspian Gull g-N|F. Note P7. | April 28 2025: female Caspian Gull g-N|F. |
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| partner 2 | May 7th, 2020: male cachinnans. | May 7th, 2020: male cachinnans. | March 23rd, 2021: male cachinnans. |
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| March 27th, 2022: male cachinnans. | c | March 27th, 2022: male cachinnans. | |
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| April 26th, 2023: male cachinnans. | April 23 2024: female at nest. | April 23 2024: male guarding. | |
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| partner 1 | April 28 2025: male Caspian Gull g-N|D. | April 28 2025: male Caspian Gull g-N|D. | April 28 2025: male Caspian Gull g-N|D. |
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| pullus | May 21st, 2021: pullus b[F|8]. | May 21st, 2021: pullus b[F|9]. | May 21st, 2021: pullus b[F|+]. |
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| pullus | May 30th, 2022: one dead chick in nest. | May 30th, 2022: one chick ringed r-7.G. | August 19th, 2022: Almere, r-7.G fledged. |
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| pullus | June 18 2024: chick g-A|0. | May 7th, 2024: chick g-A|2. | May 7th, 2024: one egg infertile. |
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| pullus | July 09 2025: chick g-T|A. | July 09 2025: chick g-T|B. | . |
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| food | May 14 2024: Roach. | June 04 2024: fish bolus by g-A|0. | April 28 2025: chicken bolus by g-N|D. |
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| April 28 2025: fish bolus by g-N|F. | |||
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Visits and data 2020.
| date: | egg no: | width (mm) | length (mm) | volume (cm3): | water test on May 7th: | |
| 07-05-2020 | A | 50,8 | 70,3 | 91,34 | 90 - tip at bottom. | 3 eggs in the nest, one partner argenteus, one partner cachinnans. |
| B | 49,8 | 73,9 | 92,28 | 90 - tip at bottom. | ||
| C | 47,3 | 76,3 | 85,95 | 90 - tip at bottom. | ||
| sum nest: | 269,57 | |||||
| 21-05-2020 | eggs | Still 3 eggs present. | ||||
| Visits and data 2021. | ||||||
| 24-03-2021 | 2 adults at this location. | |||||
| 06-05-2021 | 2 adults guarding at blocks. Red flag "71" placed to mark location. | |||||
| egg no: | width (mm) | length (mm) | volume (cm3): | water test on May 6th: | ||
| A | 50,7 | 74,5 | 96,42 | 90 - tip at bottom. | ||
| B | 50,3 | 70,3 | 89,56 | 90 - tip at bottom. | ||
| C | 50,4 | 71,1 | 90,93 | 90 - tip at bottom. | ||
| sum nest: | 276,91 | |||||
| 13-05-2021 | no visit, Camilla is trapping a Spoonbill. | |||||
| 15-05-2021 | nest with 3 eggs. Flag put up again, for it was not visible. | |||||
| metal ring | plastic | head + bill: | ||||
| 28-5-2021 | pullus | .5559422 | b-F|8 | 64 | ||
| pullus | .5559423 | b-F|9 | 52 | |||
| pullus | .5559424 | b-F|+ | 62 | |||
| 08-06-2021 | 1 adult at this location. All 3 chicks fledged. 100% success. | |||||
Visits and data 2022 for nest 34
(coded 130 on bitumen in 2022):
Estimation egg laying: A-egg = April 20 2022. Estimating hatching = May 18 2022.
| length (mm) | width (mm) | volume (cm3): | water test on April 27th: | ||||
| 27-04-2022 | A egg | 70,9 | 48,3 | -- | 20 gr - tip bottom | ||
| B egg | 73,6 | 50,3 | -- | 40 gr - tip bottom | |||
| C egg | 73 | 49,2 | -- | 40 gr - tip bottom | |||
| One parent is cachinnans (partner 1) | |||||||
| 17-05-2022 | female Herring Gull argenteus next to nest. | ||||||
| A egg: in tact. | |||||||
| C egg: with small hole. | |||||||
| B egg: hatched | |||||||
| metal | darvic | mass | wing | H+B | bill | ||
| 30-05-2002 | pullus | NLA 5625188 | r-7.G | 454 | 80 | 79,9 | 33,2 |
| One pullus dead in nest. | |||||||
| 28-06-2022 | image of r-7G. Together with female Herring gull and sibling (unringed). | ||||||
| 12-07-2022 | image of r-7G. | ||||||
| 17-07-2022 | image of r-7G. | ||||||
| data for nest 34-2023 | ||||
| dam: | dam 1 blocks | |||
| location: | Western part of blocks. Nest is same as 34/130. Code 130 on bitumen, branch with 2 stripes. | |||
| breeders: | cach x teus | |||
| OBSERVATIONS: | ||||
| 9-4-2023 | nest: | no eggs but nest is ready. | ||
| 26-4-2023 | eggs: | 1 egg. Not measured, really cachinnans? | ||
| nest: | Branch with 2 stripes is now rotten. Placed in front of nest, visible from N-side. | |||
| 11-5-2023 | eggs: | 3 eggs, not measured. Is this the wrong nest? | ||
| 27-5-2023 | nest: | The branch with 2 stripes taken away, and placed vertically at (new nest) 26. We will skip nest 34 this year. | ||
Visits and data 2024.
| NEST code | parent 1 | parent 2 | A_length | A_width | A_volume | B_length | B_width | B_volume | C_length | C_width | C_volume | TOTAL NEST: | |
| cach | 71,3 | 50,2 | 90,47 | 71,1 | 50,2 | 90,21 | 66,4 | 49,5 | 81,92 | 262,60 | |||
| 034-2024 | # eggs | A-egg | hatch | # ringed chicks | # all chicks | # fledged chicks | comments | ||||||
| 3 | 8-4-2024 | 3-5-2024 | |||||||||||
| dam: | dam 1 blocks | ||||||||||||
| location: | Nest "rode flap": at blocks, just west of open tarmac, was 'nest with the branch 2022', now with red flag and black root-cloth. | ||||||||||||
| parents? | same as 2023? | ||||||||||||
| ring pulli: | 09-May | ||||||||||||
| date | darvic | metal | location / nest# | species | sexe | age | wing | mass | head+ bill | bill | tarsus | gonys | greyscale |
| 07-05-2024 | g-A|0 | .5631235 | 34 | PONT | 1CY | 125 | |||||||
| 07-05-2024 | g-A|2 | .5631236 | 34 | PONT | 1CY | 84 | |||||||
| 14-05-2024 | g-A|0 | .5631235 | 34 | PONT | 1CY | 349 | CONTROLL | ||||||
| 14-05-2024 | g-A|2 | .5631236 | 34 | PONT | 1CY | 272 | DEAD | ||||||
| 04-06-2024 | g-A|0 | .5631235 | 34 | PONT | 1CY | 274 | 811 | 112,8 | CONTROLL | ||||
| OBSERVATIONS: | |||||||||||||
| 12-04-2024 | eggs: | 3 eggs, measured. | |||||||||||
| 21-04-2024 | eggs: | 3 eggs, not measured. | |||||||||||
| adult: | Caspian Gull incubating. | ||||||||||||
| 07-05-2024 | eggs: | 1x cold, probably infertile | |||||||||||
| chicks: | 2x ringed. | ||||||||||||
| 14-05-2024 | chicks: | CONTROLL 2 chicks. | |||||||||||
| food: | Roach 2x | ||||||||||||
| 31-05-2024 | chick: | g-A|2 dead <1 days. | |||||||||||
| 04-06-2024 | pullus | g-A|2 dead. Rings removed. | |||||||||||
| chicks: | g-A|0 present, measured. | ||||||||||||
| food: | fish bolus by g-A|0 when processed. | ||||||||||||
| 18-06-2024 | chick: | g-A|0 present. | |||||||||||
Visits and data 2025 g-N|D & g-N|F (034).
| 2025 | parent 1 | parent 2 | A_length | A_width | A_volume | B_length | B_width | B_volume | C_length | C_width | C_volume | TOTAL NEST:
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# eggs | |
| g-N|D & g-N|F (034) | cach | 69 | 50,8 | 67,7 | 52,3 | 66 | 48,7 | 3 | ||||||
| dam: | dam 1 blocks
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| location: | Nest 34 Roodflapje, at blocks east part, nest red flag
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| ouders: | same as 2024, this year trapped. Now male is g-N|D and female is g-N|F.
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| ringed: | ||||||||||||||
| date | darvic | metal | location / nest# | species | sexe | age | wing | mass | head+ bill | bill | tarsus | gonys | greyscale | |
| 28-04-2025 | g-N|D | 5641013 | 34, roodflapje | PONT | M | >4CY | 474 | 1200 | 132 | 62,1 | 76 | 20 | 5 | |
| 28-04-2025 | g-N|F | 5641014 | 34, roodflapje | PONT | F | >4CY | 436 | 972 | 123,8 | 54,4 | 66,6 | 18,8 | 7 | |
| 13-05-2025 | g-T|A | 5641063 | 34 | PONT | pullus | 376 | ||||||||
| 13-05-2025 | g-T|B | 5641064 | 34 | PONT | pullus | 373 | ||||||||
| 13-05-2025 | g-T|C | 5641065 | 34 | PONT | pullus | 270 | ||||||||
| 09-06-2025 | G-T|A | 5641063 | PONT | pullus | 764 | CONTROL | ||||||||
| 14-06-2025 | G-T|A | PONT | pullus | 851 | CONTROL | |||||||||
OBSERVATIONS:
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| 23-04-2025 | eggs | 3 eggs, measured, Small sizes!
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| 28-04 | eggs | 3 eggs | ||||||||||||
| adult | trapped both adult at nest nowg-N|D and g-N|F
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| food | g-N|D hasa bolus of chicken + fish, g-N|F has bolus of fish (roach and perch)
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| 01-05 | adult | both partners present | ||||||||||||
| 08-05 | adult | both partners present
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| 13-05 | chicks | 3x chicks ringed
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| 09-06 | chicks | g-T|A found and measured
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| 14-06-2025 | chicks | g-T|A found and measured
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