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 060
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).
- Location marked with code "60" on tarmac dam.
- Nest 060 on breakwater dam 1 south section, just on north side, near the top. Easy to trap the adults here.
- Cluster of 5 nests within 10 meters range: 3x cachinnans and 2x argentatus, which are extremely difficult to monitor. Next to Angelica is nest 60, next to blackberries complex are nest 62 & nest 63.
- ID uncertain in 2021, male is probably Caspian Gull cachinnans.
- ID certain in 2022, male and female are Caspian Gull cachinnans. Early breeders. Most probably same bird as in 2021.
- ID certain in 2023, male and female are Caspian Gull cachinnans. Early breeders. female trapped on 3-egg clutch, now r-F.7.
| location | April 24th, 2021: cluster of nests. | April 24th, 2021: red spray "60". | May 13th, 2021: Angelica nest 60. |
 |
 |
 |
|
| April 12th, 2022: Angelica nest 60. | April 19th, 2022: Angelica nest 60. | May 1st, 2022: nest 60 & neighbours. | |
 |
 |
 |
|
| eggs | April 24th, 2021: 3 eggs in nest. | April 11th, 2022: 3 eggs in nest. | April 9th, 2023: 2 eggs in nest. |
 |
 |
 |
|
| partner 1 | May 13th, 2021: adult male cachinnans. | May 13th, 2021: adult male cachinnans. | May 13th, 2021: adult male cachinnans chasing neighbour. |
 |
 |
 |
|
| partner 1 | April 12th, 2022: adult male cachinnans. | April 12th, 2022: adult male cachinnans. | April 19th, 2022: adult male cachinnans. |
 |
 |
 |
|
| partner 1 | June 18th, 2023: adult male cachinnans. | May 13th, 2023: adult male cachinnans. | . |
 |
 |
||
| partner 2 | April 24th, 2021: probable parent nest 60. | April 19th, 2022: adult female cachinnans. | April 19th, 2022: adult female cachinnans. |
 |
 |
 |
|
| partner 2 | May 1st, 2022: adult female cachinnans. | May 1st, 2022: adult female cachinnans. | June 2nd, 2022: female cachinnans protecting chicks. |
 |
 |
 |
|
| partner 2 | May 3rd, 2023: female r-F.7. | May 3rd, 2023: female r-F.7. | July 8th, 2023: female r-F.7 & male cachinnans & chick. |
 |
 |
 |
|
| pulli 2021 | May 13th, 2021: 2 cachinnans pulli. | May 28th, 2021: cachinnans pullus b[F|0]. | May 28th, 2021: cachinnans pullus b[F|1]. |
 |
 |
 |
|
| pulli 2022 | May 9th, 2022: cachinnans pullus r[C.A]. | May 17th, 2022: cachinnans pullus r[C.B]. | June 21st, 2022: cachinnans pullus r[C.B]. |
 |
 |
 |
|
| June 21st, 2022: cachinnans pullus r[C.C]. | June 25th, 2023: cachinnans pullus r[8.C]. | July 8th, 2023: cachinnans pullus r[8.=]. | |
 |
 |
 |
Visits and data.
| date: | ||||||||
| 24-04-2021 | Probably 2 partners present, but difficult to allocate birds to the nests. Nest allows trapping breeders, but early nest! | |||||||
| One partner is fierce male Caspian Gull. | ||||||||
| 3 eggs in nest. | ||||||||
| egg no: | width (mm) | length (mm) | volume (cm3): | water test on April 24th: | ||||
| A egg | 50,2 | 68,3 | 86,66 | 90 - floating halfway | ||||
| B egg | 47,9 | 64,6 | 74,63 | 90 - floating halfway | ||||
| C egg | no measurements due to cracks in shell | |||||||
| sum nest: | -- | |||||||
| 26-04-2021 | Pictures taken from canoe, of several birds flying around nests 60-62-63. How to monitor, telescope? | |||||||
| 13-05-2021 | 2 chicks of nest 60 hide underneath Angelica cover, 45 cm's from nest. | |||||||
| 15-05-2021 | Fish at nest: Rounded Goby 3x. Chick 2 vomited Rounded Goby (pellet taken for analysis). | |||||||
| mass | head+bill (measurements Monika Ballmann) | |||||||
| pullus | 257 gr | 68,2 | ||||||
| pullus | 261 gr | 68,5 | ||||||
| metal | tibia | head + bill | comments: | |||||
| 28-05-2021 | pullus | .5559412 | b-F|0 | 92,3 | Large pullus (16-18 days old), likely cachinnans from nest 60. | |||
| pullus | .5559413 | b-F|1 | 95,3 | Large pullus, likely cachinnans from nest 60. | ||||
| pullus | .5559414 | b-F|2 | 75,8 | Possibly argentatus, not necessarily from neighbour's nest, b-F|3 broken. | ||||
| pullus | .5559415 | b-F|4 | 73,2 | Possibly argentatus, not necessarily from neighbour's nest, b-F|3 broken. | ||||
| pullus | .5559416 | b-S|3 | 56,8 | Likely argentatus, from neighbour's nest. | ||||
| pullus | .5559417 | b-S|4 | 57,2 | Likely argentatus, from neighbour's nest. | ||||
| 08-06-2021 | 3 adult Caspian Gulls present. No chicks visible from canoe, not on south nor on north side from water. They probably hide in blackberries complex. | |||||||
Visits and data 2022:
Estimation egg laying: A-egg = April 6 2022??? Estimating hatching = May 4 2022.
| date: | |||||||
| 11-04-2022 | 3 eggs. | ||||||
| 12-04-2022 | Picture of adult male Caspian. | ||||||
| egg no: | width (mm): | length (mm): | volume (cm3): | water test | |||
| 15-04-2022 | A-egg | 51,2 | 70,1 | -- | 40 - tip on bottom | ||
| B-egg | 48,9 | 68,5 | 30 - tip on bottom | ||||
| C-egg | 51,1 | 70 | -- | 50 - tip on bottom | |||
| sum nest: | -- | ||||||
| 19-04-2022 | Adult breeding & 1 adult guarding. | ||||||
| egg no: | width (mm): | length (mm): | volume (cm3): | water test | |||
| 27-04-2022 | A-egg | 5 mm - floating | |||||
| B-egg | 5 mm - floating | ||||||
| C-egg | 5 mm - floating | ||||||
| 01-05-2022 | 2 adult Caspians, male has spot on P5. | ||||||
| 04-05-2022 | 3 eggs - little cracks in shell. hatching date will be 6th May. | ||||||
| 09-05-2022 | metal | darvic | mass | wing | H+B | ||
| pullus | NLA 5.625.051 | r-C.A | 117 | ||||
| pullus | NLA 5.625.052 | r-C.B | 91 | ||||
| pullus | NLA 5.625.053 | r-C.C | 137 | ||||
| 17-05-2022 | metal | darvic | mass | wing | H+B | ||
| pullus | NLA 5.625.051 | r-C.A | 483 | ||||
| pullus | NLA 5.625.052 | r-C.B | 388 | ||||
| pullus | NLA 5.625.053 | r-C.C | 530 | ||||
| food | loads of fish near the nest. | ||||||
| 02-06-2022 | r-CB & r-CC swimming northside of dam, 80 meters from nest. Large chicks, protected by female. r-CB gives up food pellet: fish. | ||||||
| 17-06-2022 | One large chick from nest 60 flies out over Markermeer. And back again. | ||||||
| 22-06-2022 | r-CB & r-CC swimming northside of dam, 200 meters from nest. Large chicks, protected by parent. | ||||||
| 12-07-2022 | Picture of r-CC. | ||||||
| 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 | 60-2023 | 68,2 | 51 | 89,31 | 69,9 | 51 | 91,54 | 66,2 | 50,2 | 84,00 | 264,85 | same as 2022 |
| ring pulli: 11-mei | laying A egg: 6-apr | hatch A egg: 4-mei | ||||||||||
| catch: | date: | metal: | darvic: | mass: | wing: | head+bill: | bill: | gonys: | greytone: | tarsus kor: | ||
| adult | 03-5-2023 | NLA 6214901 | R-F.7 | 810? | 447 | 125,6 | 57,5 | 18 | 6 | female cach | ||
| pullus | 11-5-2023 | NLA 5556469 | R-8.= | |||||||||
| pullus | 11-5-2023 | NLA 5556470 | R-8.T | |||||||||
| pullus | 11-5-2023 | NLA 5556471 | R-8.C | |||||||||
| pullus | 27-5-2023 | NLA 5556469 | R-8.= | 872 | 109,3 | 45,8 | 14 | 72,8 | ||||
| 60-2023 | ||
| dam: | dam 1 west | |
| location: | Is nest 60-2021/22. From cluster 60-62-63. | |
| breeders: | cach x cach | |
| OBSERVATIONS: | ||
| 09-04-2023 | nest: | 2 eggs measured. No watertest, ring chicks in 1st session. |
| 22-04-2023 | nest: | 3 eggs measured. |
| 03-05-2023 | adult: | Female partner ringed R-F.7. |
| 11-05-2023 | pulli: | 3 chicks ringed. |
| 13-05-2023 | adult: | both parents are cach. |
| 18-05-2023 | pulli: | 3 chicks present. |
| 27-05-2023 | pulli: | 1x control chick. |
| 18-06-2023 | adult: | R-F7 guarding juveniles. |
| pulli: | R-8= & R-8C present at water. At least 2x fledged. | |
| 25-06-2023 | pulli: | R-8=, R-8C and R-F7 (mother) present. |