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 231 (2024: g-A|C, 2025: g-A|C)
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 231 positioned on dam 2 - west: low on blocks just 5 meters southwest of nests 203 & 204, and right beneath nest 229.
- ID uncertain in 2022: one parent is cachinnans, other parent unknown.
- ID certain in 2023: both parents are cachinnans. Nest aka "nest with orange football".
- ID in 2024: both parents are same cachinnans as in 2023. Female trapped in 2024, now g-A|C.
- ID in 2025: both parents are same cachinnans as in 2023. Female g-A|C. First egg on April 1st, 2025.
| location | April 29th, 2022: location of nest. | April 29th, 2022: 2 eggs. | April 4th, 2025: on eggs. |
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| partner 1 | May 1st, 2022 adult cachinnans at nest. | April 21st, 2024: location of nest. | April 21st, 2024: full clutch, with 3 eggs. |
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| partner 1 | May 1st, 2022 adult cachinnans. | May 1st, 2022 adult cachinnans. | May 1st, 2022 adult cachinnans. |
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| partner 1 | April 27th, 2023 adult female cachinnans. | April 27th, 2023 adult female cachinnans. | April 27th, 2023 adult female cachinnans. |
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| partner 1 | April 23rd, 2024: female cachinnans. | April 23rd, 2024: female cachinnans. | April 26th, 2024: female cachinnans, now g-A|C. |
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| partner 2 | May 13th, 2023 male cachinnans type (or hybrid). | May 13th, 2023 male cachinnans type (or hybrid). | May 13th, 2023 male cachinnans type (or hybrid). |
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| partner 2 | April 23rd, 2024: male cachinnans-type. | April 23rd, 2024: male cachinnans-type. | April 23rd, 2024: male cachinnans-type. |
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| pullus | July 18th, 2023: fledged r[7.4]. | July 18th, 2023: fledged r[7.5]. | December 6th, 2023: fledged r[7.6]. |
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| pullus | June 18th, 2024: chick g-B|G. | June 18th, 2024: chick g-B|H. | May 7th, 2024: chick g-B|J. |
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| prey | May 22nd, 2022: prey is fish. | . | . |
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Visits and data.
| nest 231-2022 | date A egg: April 14 | hatch A egg: May 14 | ring chicks: May 22 | |||
| 29-04-22 | 2 eggs | A egg | 67,8 | 49,7 | tip bottom - 90 gr | 5 mtr S of nests 203/204, low on blocks |
| B egg | 60,8 | 48,5 | tip bottom - 90 gr | red spot + code sprayed near nest | ||
| 01-05-22 | adult cachinnans at nest. | |||||
| 17-05-22 | mixed pair? Possibly cachinnans and argenteus at nest? | |||||
| 1 egg present, and likely 1 chick (but not found in vegetation). | ||||||
| 22-05-22 | 1 egg is infertile | |||||
| no chicks found, but fish prey at nest indicative of offspring. | ||||||
| prey: perch and roach. | ||||||
| 17-06-22 | adult cachinnans with 1x unringed chick (P7 fully grown / can not fly yet). | |||||
| 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 | 231-2023 | 66,7 | 50,5 | 85,65 | 66,5 | 51,9 | 90,19 | 66,1 | 52 | 89,99 | 265,83 | No |
| ring pulli: | laying A egg: | hatch A egg | ||||||||||
| catch: | date: | metal: | darvic: | mass: | ||||||||
| Pullus | 11-5-2023 | 5.556.451 | r-7.4 | very small chick | ||||||||
| Pullus | 11-5-2023 | 5.556.452 | r-7.5 | small chick | ||||||||
| Pullus | 11-5-2023 | 5.556.453 | r-7.6 | very small chick | ||||||||
| Pullus | 18-5-2023 | r-74 | present | |||||||||
| Pullus | 27-5-2023 | 5.556.452 | r-75 | 730 | wing: | head+bill: | ||||||
| Pullus | 18-6-2023 | r-74 | 1041 | 338 | 118,4 | |||||||
| 231-2023 | nest 'orange football'. | |||||
| dam: | dam 2 west | |||||
| location: | 5 mtr south of 203/204. Near waterfront | |||||
| breeders: | cach x cach | |||||
| OBSERVATIONS: | ||||||
| 04-04-2023 | adult: | 1 cach at nest location. | ||||
| 09-04-2023 | nest: | nest empty | Water test: | |||
| 26-04-2023 | nest: | 3 eggs. Measured & water test: | A | 90 - tip bottom | ||
| B | 90 - tip bottom | |||||
| 27-04-2023 | adult: | breeding female cach | C | 80 - tip bottom | ||
| 11-05-2023 | pulli | 3 chick ringed | ||||
| 13-05-2023 | adult: | 2x cach adults, 1 chick in nest, legs not visible. | ||||
| 18-05-2023 | nest: | R-74 present, other not found | ||||
| 18-06-2023 | pulli | r-74, r-75 & r-76 swimming together, only r-74 trapped & measured. Fledged: 3 chicks. | ||||
| 25-06-2023 | pulli | r-74, r-75 and r-76. All 3 chicks fledged. | ||||
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 | cach | 70 | 52 | 95,30 | 67,9 | 50,9 | 88,57 | 68 | 51,5 | 90,81 | 274,68 | ||
| 231-2024 | # eggs | A-egg | hatch | # ringed chicks | # all chicks | # fledged chicks | comments | ||||||
| 3 | 4-4-2024 | 2-5-2024 | |||||||||||
| dam: | dam 2 west | ||||||||||||
| location: | was nest 'orange football' 2023, | ||||||||||||
| parents? | Same as 2023. | ||||||||||||
| ring pulli: | 6-May | ||||||||||||
| date | darvic | metal | location / nest# | species | sexe | age | wing | mass | head+ bill | bill | tarsus | gonys | greyscale | 26-04-2024 | g-A|C | .5625297 | voetbal (231) | PONT | F | >4CY | 439 | 121,0 | 53,8 | 69,1 | 17,9 | 6 |
| 07-05-2024 | g-B|G | .5631154 | 231 football | PONT | 1CY | 90 | |||||||
| 07-05-2024 | g-B|H | .5631155 | 231 football | PONT | 1CY | 147 | |||||||
| 07-05-2024 | g-B|J | .5631156 | 231 football | PONT | 1CY | 136 | |||||||
| OBSERVATIONS: | |||||||||||||
| 21-04-2024 | eggs: | 3 eggs, measured. | |||||||||||
| 26-04-2024 | adult: | adult female trapped at nest, now g-A|C. | |||||||||||
| 02-05-2024 | eggs: | 2 eggs, 1x hatched halfway. | |||||||||||
| chicks: | 1 chick, hatched this morning. | ||||||||||||
| 07-05-2024 | chicks: | 3x ringed. | |||||||||||
| 04-06-2024 | pullus: | g-B|J dead, >7 days. Rings removed. | |||||||||||
| adult: | 2x, both parents in territory. | ||||||||||||
| 18-06-2024 | chick: | CONTROLL: g-B|G at water, g-B|H at blocks near territory. | |||||||||||