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 x argenteus - nest Lelystad 006
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 006 positioned on artificial breakwater 1 at T-split. Location is nest PLDP - 2020 (in 2021, PLDP moved to nest PESV).
In 2023 location used by mixed pair Caspian Gull & Herring Gull. - Certainty on ID in 2021, breeders are male Caspian Gull cachinnans and female Herring Gull argenteus.
- Certainty on ID in 2023, breeders are male Caspian Gull cachinnans and female Herring Gull argenteus.
- No certainty on ID in 2024, 2x Caspian Gull cachinnans and 1x Herring Gull argenteus present.
| location | April 16th, 2021: male cach & female teus. | April 12th, 2024: 1 egg. | April 21st, 2024: 3 eggs. |
 |
 |
 |
|
| eggs | April 21st, 2024: 3 eggs. | . | . |
 |
|||
| nest | April 16th, 2021: male cach & female teus. | May 6th, 2021: male cach & female teus. | June 8th, 2021: too many cachinnans! |
 |
 |
 |
|
| nest | April 27th, 2023. Caspian x Herring nest. | April 27th, 2023. Caspian x Herring nest. | . |
 |
 |
||
| partner 1 | April 27th, 2023. Caspian "almost thayeri P10". | April 27th, 2023. Caspian "almost thayeri P10". | April 27th, 2023. Caspian "almost thayeri P10". |
 |
 |
 |
|
| partner 1 | April 26 2024: Caspian Gull is guarding. | April 26 2024: Caspian Gull 2023 is neighbour? | April 30 2024: Caspian Gull 2023 is neighbour? |
 |
 |
 |
|
| partner 1 | April 01 2025: Caspian Gull 'Injured leg' & thayeri pattern. | . | . |
 |
|||
| partner 2 | April 26 2024: River Gull type is incubating. | April 26 2024: River Gull type is incubating. | April 26 2024: River Gull type is incubating. |
 |
 |
 |
|
| partner 2 | May 14 2024: River Gull type. | May 14 2024: River Gull type. | May 14 2024: River Gull type. |
 |
 |
 |
|
| pulli | May 28th, 2021: pullus, likely wrong nest. | May 14th, 2024: pullus g-C|B. | . |
 |
 |
Visits and data.
| date: | ||||||
| 16-04-2021 | Two adult at nest, photographed. Nest without eggs. Many Spoonbills breeding here, hampering visits in future. | |||||
| 24-04-2021 | Correction on flag code. Now labeled "6". Nest abandoned, no eggs? | |||||
| 26-04-2021 | No visit, Camilla is trapping a Spoonbill. | |||||
| 06-05-2021 | egg no: | width (mm) | length (mm) | volume (cm3): | water test on May 6th: | 3 eggs in nest |
| A egg | 49,2 | 68,7 | 83,73 | 25 - tip at bottom | ||
| B egg | 50,7 | 71,7 | 92,80 | 30 - tip at bottom | ||
| C egg | 51,9 | 71,5 | 96,97 | 55 - tip at bottom | ||
| sum nest: | 273,50 | |||||
| 15-05-2021 | 2 eggs in nest. Nest located at 'the flat stone' in dense, inaccessible Blackberry complex. | |||||
| 28-05-2021 | metal | tibia | mass (gr) | head + bill (mm) | ||
| pullus | .5559419 | -- | -- | -- | Chick is 1 day old. Only metal ringed. No certianty about species. | |
| 1 egg: just hatching. | ||||||
| In retrospect: this nest was situated 'too high' at dam 1, likely different nest. Hybrid nest is situated at flat stone, lower and central at dam (see May 15th). | ||||||
| 08-06-2021 | Sitiuation not clear: several cachinnans and argenteus here guarding 3 large chicks. Favorite place for chicks at the blocks near waterfront, below Blackberry complex. | |||||
| 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 | 6-2023 | 71,2 | 49,7 | 88,55 | 69,7 | 49,2 | 84,95 | 69,7 | 47,4 | 78,85 | 252,35 | New nest. |
| 006-2023 | OLD LOCATION PESV | |
| dam: | dam 1 T-split | |
| location: | old nest yPESV, N of Elder bush (Vlierstruik), visible from West. | |
| breeders: | cach x teus | |
| OBSERVATIONS: | ||
| 09-04-2023 | 1 adult | Guarding cach type with yellow legs. |
| 27-04-2023 | adult: | 1x teus and 1x cach at nest location. Quickly returning. Should check for nest here. |
| Check cach from pictures 2022: this is a known bird (the 'almost thayeri'.)… | ||
| 13-05-2023 | adult: | again, the cach with limpy left leg. |
| 27-05-2023 | nest: | 3 eggs measured. |
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: | |
| 006-2024 | 68,9 | 48,8 | 82,61 | 68 | 49,7 | 84,57 | 67 | 48,6 | 79,68 | 246,87 | |||
| # eggs | A-egg | hatch | # ringed chicks | # all chicks | # fledged chicks | comments | |||||||
| 3 | 11-4-2024 | 7-5-2024 | |||||||||||
| dam: | dam 1 T-split | ||||||||||||
| location: | Nest limping leg "mankevoetje", visible from west. Top of dam (was yPESV-20). Yellow smiley skippy placed near nest & Blue chair S. | ||||||||||||
| parents? | same as 2023? | ||||||||||||
| ring pulli: | 12-May | ||||||||||||
| date | darvic | metal | location / nest# | species | sexe | age | wing | mass | head+ bill | bill | tarsus | gonys | greyscale |
| 14-05-2024 | g-C|B | .5631199 | nest 6 (stoel Z) | PONT | 1CY | 141 | |||||||
| 31-05-2024 | g-C|B | .5631199 | nest 6 (stoel Z) | PONT | 1CY | ||||||||
| OBSERVATIONS: | |||||||||||||
| 12-04-2024 | eggs: | 1 egg, measured. Yellow smiley skippy placed near nest Mankevoetje. | |||||||||||
| 21-04-2024 | eggs: | 3 eggs, measured. | |||||||||||
| nest: | Blue chair placed = Blue chair South | ||||||||||||
| 26-04-2024 | adults: | Caspian Gull female is guarding, River Gull is incubating, partner 1-2023 (limpy leftie) is neighbour with Herring Gull. | |||||||||||
| 30-04-2024 | adults: | Limy Leftie seems to nest just S of blue chair? | |||||||||||
| 07-05-2024 | eggs: | 3x. | |||||||||||
| 14-05-2024 | chicks: | 1x ringed. | |||||||||||
| eggs: | 1x in nest. | ||||||||||||
| 31-05-2024 | chicks: | CONTROLL: g-C|B. | |||||||||||