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 251 "Ariel"
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).
- 2023: Nest 251 positioned on dam 2 west section: 1 mtr N blue sign VHF20, 2 mtr behind "the white buoy". Could be parents nest 12-2020/2022.
- ID uncertain in 2023: one parent is cachinnans, other parent unknown. Likely both cachinnans, but, might be Herring blood involved, as the chicks show intermediate traits.
- ID certain in 2024. Female cachinnans is same as in 2023. Male is also cachinnans.
- In 2025 breeding birds at nest 251 "Ariel" are Caspian Gulls, including b-F|=. See nest info HERE. Named after Ariel detergent container next to nest.
- In 2026: nest 'Ariel' same location as 2025.
| location | April 9th, 2023: nest location dam 2. | March 21 2025: 2 eggs in nest "Ariel". | April 22nd, 2026: 'Ariel' nest location dam 2. |
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| nest | April 9th, 2023: full clutch, with 3 eggs. | April 21st, 2024: full clutch, with 3 eggs. | April 21st, 2025: 2 eggs (is max for 2025). |
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| nest | April 22nd, 2026: full clutch, with 3 eggs. | . | . |
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| partner 1 | April 27th, 2023: breeding adult cachinnans. | April 27th, 2023: adult cachinnans. | . |
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| partner 1 | April 23rd, 2024: female cachinnans. | April 23rd, 2024: female cachinnans. | April 23rd, 2024: female cachinnans. |
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| partner 2 | April 23rd, 2024: male cachinnans. | April 23rd, 2024: male cachinnans. | April 23rd, 2024: male cachinnans. |
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| April 23rd, 2024: male cachinnans. | . | . | |
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| pullus | November 29th, 2023: fledged r[7.U]. | June 25th, 2023: fledged g[7|V]. | . |
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| pullus | June 18th, 2024: chick g-A|=. | May 7th, 2024: chick g-B|A. | May 7th, 2024: chick g-B|B. |
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Data for nest 251-2023:
| 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 cach | 251-2023 | 70,7 | 50 | 88,99 | 68,1 | 51,4 | 90,59 | 67,7 | 49,1 | 82,18 | 261,76 | was 12-2022??? |
| ring pulli: May 10 | laying A egg: April 05 | hatch A egg: May 03 | ||||||||||
| catch: | date: | metal: | darvic: | mass: | wing: | head+bill: | ||||||
| Pullus | 11-5-2023 | 5.625.193 | r-7.U | 315 | 75.0 | 75.0 | two other chicks? Chicks not found | |||||
| Pullus | 18-5-2023 | 5.556.411 | g-7|V | 490 | 86,3 | 86,3 | ||||||
| Pullus | 18-5-2023 | 5.625.193 | r-7U | not measured, but was present. | ||||||||
| Pullus | 27-5-2023 | 5.625.193 | r-7U | 896 | ||||||||
| Pullus | 18-6-2023 | 5.625.193 | r-7U | |||||||||
| Pullus | 18-6-2023 | 5.556.411 | g-7|V | |||||||||
| 251-2023 | nest "White Buoy". | ||
| dam: | dam 2 west | ||
| location: | 1 mtr N blue sign VHF20, 2 mtr behind of white buoy. Could be parents nest 12-2020/2022. Parents guarding from VHF20? | ||
| breeders: | cach x cach | ||
| OBSERVATIONS: | |||
| 09-4-2023 | nest: | 3 eggs measured. Watertest C-egg: 35 - tip bottom | |
| 27-4-2023 | adult: | breeding adult cach. | |
| 11-5-2023 | pulli: | 1 chick ringed r-7U, 2 more chicks? | |
| 18-5-2023 | pulli: | 2 chicks present. 1 ringed (R-7U), other unringed. The unringed one is now ringed today g-7|V. | |
| 27-5-2023 | pulli: | 1x chick measured, r-7U. | |
| 18-6-2023 | pulli: | g-7|V and r-7U together. | |
| 25-6-2023 | pulli: | G-7|V and r-7U together: 2 chicks fledged from this nest. | |
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: | |
| 70,7 | 50,7 | 91,50 | 69 | 51 | 90,36 | 69,3 | 47,3 | 78,06 | 259,93 | ||||
| 251-2024 | # eggs | A-egg | hatch | # ringed chicks | # all chicks | # fledged chicks | comments | ||||||
| 3 | 17-4-2024 | 15-5-2024 | |||||||||||
| dam: | dam 2 west | ||||||||||||
| location: | Ariel / white Buoy, 4 mtr north of Blue sign | ||||||||||||
| parents? | Same as 2023? | ||||||||||||
| ring pulli: | 20-May | ||||||||||||
| date | darvic | metal | location / nest# | species | sexe | age | wing | mass | head+ bill | bill | tarsus | gonys | greyscale |
| 07-05-2024 | g-A|= | 5.631.244 | 251 Ariel | PONT | 1CY | 71 | |||||||
| 07-05-2024 | g-B|A | 5.631.245 | 251 Ariel | PONT | 1CY | 81 | |||||||
| 07-05-2024 | g-B|B | 5.631.246 | 251 Ariel | PONT | 1CY | 82 | |||||||
| OBSERVATIONS: | |||||||||||||
| 21-04-2024 | eggs: | 3 eggs, measured. | |||||||||||
| 02-05-2024 | eggs: | 3 eggs. | |||||||||||
| 07-05-2024 | chicks: | 3x ringed. | |||||||||||
| 18-06-2024 | chick: | CONTROLL: g-B|B and g-A|= at water. | |||||||||||
Data for nest b-F|= (251-2025 "Ariel").
| 2025 | parent 1 | parent 2 | A_length | A_width | A_volume | B_length | B_width | B_volume |
| b-F|= (Ariel / 251) | cach | cach | 71,4 | 48,9 | 70 | 52,2 | ||
| dam: | dam 2 west
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| location: | 2 m N of blue sign, loaction of 2024, Ariel / white Buoy,
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| parents: | new, now b-F|= and Caspian Gull partner.
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| ring pulli: | ||||||||
| ringed: | darvic | metal | location / nest# | species | sexe | age | wing | mass |
| 31-05-2025 | G-R|0 | 5,641,925
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PONT | pullus | 780 | |||
| 09-06-2025 | G-R|0 | 5,641,925
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CONTROL | PONT | pullus | 931 | ||
| 14-06-2025 | G-R|0 | 5,641,925
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CONTROL | PONT | pullus | 1058 | ||
OBSERVATIONS:
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| 16-03-2025 | nest | 1x cach at blue sign, above nest location,
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| nest | b-F|= and unringed partner at soos dam 2,
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| 20-03 | nest | b-F|= present on VHF sign dam 2
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| 25-03 | nest | b-F|= present on VHF sign dam 2
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| 01-04 | nest | b-F|= present below VHF sign around Ariel nest, but 2 more cachs present
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| 21-04 | nest | 2 eggs, measured,
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| 28-04 | nest | 2 eggs | ||||||
| 08-05 | adult | b-f|= present
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| 13-05 | nest | empty nest, no chicks found
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| 31-05 | chicks | g-R|0 caught on water, with X60J alarming above. Ringed & measured. Chick appeared to belong to b-F|= | ||||||
| 09-06 | chicks | g-R|0 at water again, near nest b-F|=, CONTROL measure. | ||||||
| 14-06 | chicks | g-R|0 at water again, near nest b-F|=, CONTROL measure. | ||||||
Visits and data 2026.
| 2026 | 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 | |
| Ariel | cach | ? | 70,1 | 49,4 | 69,2 | 49,2 | 65,3 | 49,0 | ||||||
| ringed: | ||||||||||||||
| date | darvic | metal | location / nest# | species | sexe | age | wing | mass | head+ bill | bill | tarsus | gonys | greyscale | |
OBSERVATIONS:
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| 22-04-2026 | nest | 3 eggs, measured. | ||||||||||||
| 27-04-2026 | nest | 3 eggs. | ||||||||||||
| parents | 1x unringed Caspian Gull. | |||||||||||||
| 10-05-2026 | nest | 3 eggs. | ||||||||||||