Larus cachinnans in the Netherlands
(last update: August 16, 2020)
Coordinator:
Albert de Jong
Merijn Loeve
Roland-Jan Buijs
Thijs Horst
Leon Kelder
Mars Muusse
Cachinnans - nest r-C.G (was y-PHSV)
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 064 "PHSV" on breakwater dam 1 south section, north side of dam (unvisible from parking lot). Easy to trap the adults here in future (season 2022?).
In 2022 nest moved 10 meters west, into Blackberry bush.
In 2023 nest is at location of 2022.
In 2024: nest moved 3 meters west, now underneath the large tree. - ID certain in 2021, both breeders are Caspian Gull cachinnans, y[PHSV] is 11CY and unringed adult partner.
- ID certain in 2022, Caspian Gull cachinnans, y[PHSV] with same partner as previous season, though wingtip pattern slightly changed.
- ID certain in 2023, Caspian Gull cachinnans, r-C.G with different partner.
- ID certain in 2024, Caspian Gull cachinnans, r-C.G with male adult Caspian Gull.
- In 2025: r-CG present, with r-6X but no breeding at Lelystad. Instead, nest occupied by g-A|E & g-M|+.
| location | May 13th, 2021. | April 15th, 2022: nest moved 10 meters westwards. | June 21st, 2022: 2nd attempt, 40 meters eastwards. |
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| eggs | April 24th, 2021. | May 13th, 2021: hatching chicks. | May 15th, 2021. |
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| eggs | May 9th, 2022: hatching date. | May 17th, 2022: all 3 chicks dead in nest. | June 21st, 2022: 1 egg in 2nd attempt by partner 2. |
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| April 12th, 2024: 1 egg, behind tree. | April 21st, 2024: 3 eggs clutch. | . | |
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| partner 1 | April 26th, 2021: partner y[PHSV]. | April 26th, 2021: partner y[PHSV]. | May 13th, 2021: partner y[PHSV]. |
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| partner 1 | May 9th, 2022: female cachinnans y[PHSV] now r[C.G]. | May 9th, 2022: female cachinnans y[PHSV] now r[C.G]. | May 9th, 2022: female cachinnans y[PHSV] now r[C.G]. |
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| partner 1 | May 3rd, 2023: female cachinnans r[C.G] trapped. | April 27th, 2023: cachinnans r[C.G] on bread. | June 18th, 2023: cachinnans r[C.G] offensive. |
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| partner 1 | March 08 2024: r-CG. | March 08 2024: r-CG. | March 16 2025: r-CG. Preswent, not breeding in 2025. |
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| partner 2 | April 26th, 2021: unringed partner. | April 26th, 2021: unringed partner. | April 26th, 2021: unringed partner. |
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| partner 2 | May 13th, 2021: unringed partner. | May 13th, 2021: unringed partner. | May 28th, 2021: partner with fishline. |
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| partner 2 | April 11th, 2022: unringed male. | April 11th, 2022: unringed male. | April 27th, 2022: unringed male. |
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| partner 2 | April 27th, 2023: unringed male. | April 27th, 2023: short P10 with thayeri (right). | April 27th, 2023: normal on left wing. |
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| partner 2 | May 2nd, 2024: unringed male. | May 2nd, 2024: unringed male. | May 2nd, 2024: unringed male. |
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| pulli | May 28th, 2021: cachinnans pullus b[F|X]. | May 28th, 2021: cachinnans pullus b[F|Y]. | May 28th, 2021: cachinnans pullus b[F|Z]. |
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| pullus | July 8th, 2023: fledged r-8.1. | May 18th, 2023: metal only 5.556.486. | . |
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| pullus | May 14th, 2024: pullus g-C|G. | May 14th, 2024: pullus g-C|H. | May 14th, 2024: pullus g-C|J. |
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Visits and data.
| date: | ||||||
| 24-04-2021 | 2 partners present, one is y[PHSV] and unringed adult. Nest allows trapping breeders, easily. 3 eggs in nest. | |||||
| egg no: | width (mm) | length (mm) | volume (cm3): | water test on April 24th: | ||
| A egg | 49,4 | 75,7 | 93,01 | 45 - tip bottom | ||
| B egg | 50,6 | 76,6 | 98,75 | 45 - tip bottom | ||
| C egg | 51,6 | 73,7 | 98,80 | 65 - tip bottom | ||
| sum nest: | 290,56 | |||||
| 26-04-2021 | Both partners present. Partner 2 with small black spot on primary coverts. | |||||
| 13-05-2021 | Both partners present. | |||||
| 1 chick: 1,5 days old. | ||||||
| 1 chick: hatching | ||||||
| 1 egg: still in tact. | ||||||
| 15-05-2021 | 1 chick: mass = 88 gr. | |||||
| 1 chick: mass = 107 gr. | ||||||
| 1 egg just hatching. | ||||||
| 28-05-2021 | metal | tibia | mass | head + bill | ||
| pull | .5559409 | b-F|X | >400 | 85 | ||
| pull | .5559410 | b-F|Y | >400 | 88,5 | ||
| pull | .5559411 | b-F|Z | >400 | 78,3 | ||
| Partner 2 has fishgear in beak. | ||||||
| 08-06-2021 | 2 partners at nest. partner 2 has no longer hooked with fishline. | |||||
| 26-06-2021 | No activity. | |||||
| Visits and data for y-PHSV 2022: Estimation egg laying: A-egg = April 11 2022. Estimating hatching = May 09 2022. |
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| 15-04-2022 | 2 partners present, one is y[PHSV] and unringed adult. Nest has moved 10 meters to Blackberry complex. 2 eggs in nest. | |||||
| egg no: | width (mm) | length (mm) | volume (cm3): | |||
| A egg | 50,9 | 77,8 | -- | |||
| B egg | 50,2 | 70,9 | -- | |||
| 19-04-2022 | 1 adult at nest. | |||||
| 27-04-2022 | egg no: | width (mm) | length (mm) | volume (cm3): | water test | P-moulting adult |
| A egg | 4 mm - floating | |||||
| B egg | 4 mm - floating | |||||
| C egg | 51,6 | 71,7 | -- | 3 mm - floating | ||
| sum nest: | 290,56 | |||||
| 01-05-2022 | unringed partner at nest. | |||||
| 04-05-2022 | PHSV at nest. | |||||
| 09-05-2022 | 3 eggs. One egg hatching with little hole; 1 egg with cracks. Trap adult at nest. | |||||
| Female cachinnans y-PHSV trapped. New rings: metal = NLA 5.625.054 & r[C.G]. | ||||||
| Biometrics: wing 446; tarsus 69,3; head+bill 127,8; bill 57,8; gonys 18,3; mass 944 gr. | ||||||
| 17-05-2022 | 3 pulli dead in nest. Poisoned? About 4 days dead (avian flu?). Two adults present. End of season... | |||||
| mass | tarsus | |||||
| 94 | 3,9 | |||||
| 57 | 3,2 | |||||
| 89 | 4 | |||||
| 02-06-2022 | unringed male is still present at site. No sign of r[C.G]. | |||||
| 17-06-2022 | unringed male is still present at site. No sign of r[C.G]. | |||||
| 21-06-2022 | unringed male is still present at site. New nest is 40 mtr east of old nest, 1 egg. Also there: a sub-adult Herring Gull which may be the new partner. | |||||
| egg no: | width (mm) | length (mm) | volume (cm3): | |||
| A egg | 51,0 | 75,8 | -- | |||
| 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 | r-C.G | 0 | 0 | 0,00 | 0 | 0 | 0,00 | 0 | 0 | 0,00 | 0,00 | r-CG & new male cach |
| ring pulli:15-mei | laying A egg: 10-apr | hatch A egg: 8-mei | ||||||||||
| catch: | date: | metal: | darvic: | mass: | wing: | head+bill: | bill: | gonys: | greytone: | |||
| adult | 03-05-2023 | 5625054 | r-CG | 830 ? | 438 | 126,5 | 56,9 | 18,6 | 4 | female cach retrap | ||
| pullus | 18-05-2023 | 5556486 | -- | 74 | -- | 47,2 | -- | -- | -- | mass without ring | ||
| pullus | 18-05-2023 | 5556487 | R-81 | 77 | -- | 52 | -- | -- | -- | |||
| pullus | 27-05-2023 | 5556487 | R-81 | 397 | -- | -- | -- | -- | -- | |||
| r-C.G (was y[PHSV]) | ||
| dam: | dam 1 west | |
| location: | opposite harbour, next to largest willow. In Blackberry bush. | |
| breeders: | cach x cach | |
| OBSERVATIONS: | ||
| 22-4-2023 | nest: | 2 eggs. |
| 27-4-2023 | adult: | 2x cachinnans, parent 1 is r-CG, parent 2 is short thayeri P10. |
| nest: | in Blackberry. Location as 2022. | |
| 3-mei | adult: | retrap r-CG on 3 eggs. |
| 11-5-2023 | nest: | 3 eggs. |
| 18-5-2023 | pulli: | 2 chicks ringed, 1 egg hatching. |
| 27-5-2023 | pulli: | 1x control chick R-81. |
| 18-6-2023 | adult: | r-CG attacks near nest but no chicks found. Presenr are 2x Herring chicks from neighbour nest. |
| 25-6-2023 | pulli: | r-81 and r-CG present. |
| r-C.G (was y[PHSV]) | ||
| dam: | dam 1 west | |
| location: | opposite harbour, next to largest willow. In Blackberry bush. | |
| breeders: | cach x cach | |
| OBSERVATIONS: | ||
| 22-4-2023 | nest: | 2 eggs. |
| 27-4-2023 | adult: | 2x cachinnans, parent 1 is r-CG, parent 2 is short thayeri P10. |
| nest: | in Blackberry. Location as 2022. | |
| 3-mei | adult: | retrap r-CG on 3 eggs. |
| 11-5-2023 | nest: | 3 eggs. |
| 18-5-2023 | pulli: | 2 chicks ringed, 1 egg hatching. |
| 27-5-2023 | pulli: | 1x control chick R-81. |
| 18-6-2023 | adult: | r-CG attacks near nest but no chicks found. Presenr are 2x Herring chicks from neighbour nest. |
| 25-6-2023 | pulli: | r-81 and r-CG present. |
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: | |
| r-C.G 2024 | cach | cach | 77,1 | 50,7 | 99,79 | 76,8 | 51,3 | 101,76 | 70,6 | 50 | 88,87 | 290,42 | |
| # eggs | A-egg | hatch | # ringed chicks | # all chicks | # fledged chicks | comments | |||||||
| 3 | 11-4-2024 | 7-5-2024 | |||||||||||
| dam: | dam 1 west | ||||||||||||
| location: | Same spot: opposite harbour, next to largest willow. In Blackberry bush. | ||||||||||||
| parents? | same as 2020-2023 | ||||||||||||
| ring pulli: | 11-May | ||||||||||||
| date | darvic | metal | location / nest# | species | sexe | age | wing | mass | head+ bill | bill | tarsus | gonys | greyscale |
| 14-05-2024 | g-C|G | .5631107 | nest r-CG | PONT | 1CY | 204 | |||||||
| 14-05-2024 | g-C|H | .5631108 | nest r-CG | PONT | 1CY | 187 | |||||||
| 14-05-2024 | g-C|J | .5631109 | nest r-CG | PONT | 1CY | 109 | |||||||
| OBSERVATIONS: | |||||||||||||
| 08-03-2024 | adult: | r-CG on bread. | |||||||||||
| 19-03-2024 | adult: | r-CG on bread. | |||||||||||
| 12-04-2024 | eggs: | 1 egg, measured | |||||||||||
| 21-04-2024 | eggs: | 3 eggs, measured. | |||||||||||
| 23-04-2024 | adult: | r-CG on bread. | |||||||||||
| 02-05-2024 | eggs: | 3 eggs. | |||||||||||
| 14-05-2024 | chicks: | 3x ringed. Fish bolus (yellow) when processed. | |||||||||||
| food: | Fishes: Perch, Goby. | ||||||||||||
| 18-06-2024 | chicks: | 3x chicks present at water and able to fly. | |||||||||||
| adult: | male present. | ||||||||||||
Visits and data 2025.
| 2025 | parent 1 | parent 2 |
| r-CG & r-6X | ||
OBSERVATIONS:
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| 3/16/2025 | adult | r-CG on bread, multiple locations in colony, Flew 1x to nest location 2024
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| 3/21/2025 | nest | r-CG at nest XLDT 2024 with unringed partner
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| 3/25/2025 | adult | r-CG present around colony and Almere together with r-6.X
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| r-CG is Polish 15CY female Caspian Gull (cachinnans) | ||
| r-6X is local raised 4CY hybrid Caspian Gull (cachinnans x argentatus) | ||
| 4/23/2025 | adult | r-CG not seen for last 14 days, also no r-6X present
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