Larus cachinnans in the Netherlands

(last update: August 16, 2020)

Coordinators:
Albert de Jong
Leon Kelder
Roland-Jan Buijs
Merijn Loeve
Mars Muusse

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Cachinnans breeding in the Netherlands - past & future

you can participate in this project too!
please send in your observations of colour ringed birds to: ring@buijsecoconsult.nl

POPULATION SIZE

Obviously, Caspian Gull is a relatively early breeding species in this colony, and many birds arrive in March, when observing adults at nest location is not hampered by tall green vegetation. Therefore, estimations for the population size are assumed to be accurate.
From the kayak, at approx 40 meters distance, we observed guarding birds on the breakwaters. We then landed, searched for the eggs and placed code flags on a bamboo stick near the nest. We monitored 41 coded nests in 2020. Several nests appeared to belong to either Herring Gull or Lesser Black-backed Gull. A total of 32 nests had at least one parent Caspian Gull.
We also marked codes using paint spray, on blocks that were easily visible from the water.

For most nests, the big distance to neighbouring nests made countings easy. However, for some location we found clusters of nests, and especially in these clusters we may have missed breeding pairs.
In 2020, we did not estimate breeding numbers for neither Herring, nor Lesser Black-backed Gull.

Table 1 below:
Number of observed individuals (not pairs, not necessarily breeding) of 3 gull species at colony Kreupel - Flevoland, the Netherlands.
Note: decreasing numbers for Herring Gull may be related to the recent realisation we have to split the silvery-backed breeders into two species, Herring Gull and Caspian Gull. Also, breeding numbers for Herring Gull already fluctuated quite a lot, therefore we have to see if this is a 'genuine decrease' for that species.

year / species Lesser Black-backed Gull Herring Gull Caspian Gull Yellow-legged Gull
2004 0 1 0 0
2005 2 3 0 0
2006 3 4 0 0
2007 4 3 0 0
2008 3 6 0 0
2009 11 4 0 0
2010 15 11 0 0
2011 36 10 0 0
2012 79 24 0 0
2013 162 51 0 0
2014 141 40 1 0
2015 152 64 0 0
2016 141 52 0 0
2017 194 34 0 0
2018 223 70 2 1
2019 326 76 4 2
2020 429 45 15 1
2021 368 20 39 0

Table 2 below:
Breeding gull species at colony Lelystad - Flevoland, the Netherlands. Caspian Gull pairs is with at least 1 partner = cachinnans.

year / species Lesser Black-backed Gull Herring Gull Caspian Gull
2015 x x x
2016 x x 3
2017 x x 1+
2018 x x 3 (?)
2019 x x 13
2020 x x 27
2021 x x 41

Below: Observations of Larus cachinnans outside the breeding season at location 'Oostvaardersdijk' - Lelystad, the Netherlands.

(To add: bar graph with data).

Indien bekend: staafdiagrammetje aantalsontwikkeling kolonie.
Waarn.nl plot kaartje winterwaarnemingen Flevo.
Indien bekend staafdiagrammetje ontwikkeling Kreupel.
Broedende cachen in Nl tussen 2015-2019 indien bekend. Kaartje daarvan.
Kaartje Waarn.nl met mei-juli data adulte cachen in Nl?

Cachinnans breeding in the Netherlands - season 2019 in Flevoland.

you can participate in this project too!
please send in your observations of colour ringed birds to: ring@buijsecoconsult.nl

In 2020, we extensively monitored breeding Caspian Gulls at colony Lelystad. However, the previous year, breeding season 2019, Albert de Jong also paid three visits to Lelystad, and, together with Roland-Jan Buijs, ringed several chicks on May 16 2019.

For consistency, nests are coded as in 2020

nest 002, one parent is 7CY cachinnans y[PNED].

May 01 2019 3 eggs in nest. A-egg hatching, small cracks.
May 16 2019 2 chicks ringed: n[F|B] & NLA 5.548.151 and n[F|C] & NLA 5.548.152
May 24 2019 no data.

nest 005, one parent is 8CY cachinnans y[PLDP].

May 01 2019 no data.
May 16 2019 2 chicks ringed: male n[F|J] & NLA 5.548.157 and n[F|K] & NLA 5.548.158
May 24 2019 no data.

nest 006, one parent is 9CY cachinnans y[PESV].

May 01 2019 3 eggs in nest. A-egg hatching, small cracks.
May 16 2019 1 egg in nest and shit traces. However, chick not found.
May 24 2019 no data.

nest 008, one parent is adult female cachinnans g[XLDT].

May 01 2019 3 eggs in nest.
May 16 2019 2 chicks ringed: n[F|L] & NLA 5.548.159 and n[F|M] & NLA 5.548.160
May 24 2019 no data.

nest A2019 with cachinnans.

May 01 2019 3 eggs in nest.
May 16 2019 2 chicks ringed: n[F|D] & NLA 5.548.153 and n[F|E] & NLA 5.548.154
May 24 2019 no data.

nest B2019 with cachinnans.

May 01 2019 3 eggs in nest.
May 16 2019 2 chicks ringed: n[F|F] & NLA 5.548.155 and n[F|G] & NLA 5.548.156
May 24 2019 no data.

nest C2019 with cachinnans.

May 01 2019 3 eggs in nest.
May 16 2019 1 egg. No shit traces, no chicks.
May 24 2019 no data.

nest D2019 with cachinnans.

May 01 2019 no data.
May 16 2019 3 eggs discovered today.
May 24 2019 no data.

nest E2019 with cachinnans.

May 01 2019 no data.
May 16 2019 3 eggs discovered today.
May 24 2019 no data.

nest F2019 with cachinnans.

May 01 2019 3 eggs in nest.
May 16 2019 2 chicks ringed: n[F|N] & NLA 5.548.161 and n[F|P] & NLA 5.548.162
May 24 2019 no data.

nest G2019 with cachinnans.

May 01 2019 no data.
May 16 2019 3 eggs discovered today. A-egg hatching, small cracks.
May 24 2019 alarming cachinnans here.

 

 
 
 
 
 
Caspian Gull Larus cachinnans XLDT 8CY, immgirant from eastern Germany now breeding at Lelystad colony, labelled "nest 08".
T
he Netherlands (52°30'36.17"N 005°25'11.70"E).
Caspian Gull Larus cachinnans PESV 10CY and Caspian Gull Larus cachinnans PLDP 9CY, both immgirants from Polish colonies and now breeding side-by-side at Lelystad colony, labelled "nest 06" and "nest 05" respectively.
T
he Netherlands (52°30'36.17"N 005°25'11.70"E).

Caspian Gull Larus cachinnans P:G76 3CY at Lelystad colony. A potential breeder in the near future?
June 02 2020, Lelystad, the Netherlands.

Ringed as pullus on May 13 2018 in a mixed "Caspian Gull colony" at WYSPA NA RZ.WISŁA,KĘPA ADBRZESKA, OTWOCK POLAND. Ringer: Marcin Sidelnik.

Caspian Gull Larus cachinnans PNED 8CY, May 07 2020, Lelystad, the Netherlands.
Parent of
"nest 002" in season 2019 and 2020. Originally, ringed as pullus in Poland.
Caspian Gull Larus cachinnans F|B 1CY, May 16 2019. Hatched in "nest 002" in season 2019.
Caspian Gull Larus cachinnans F|C 1CY, May 16 2019. Hatched in "nest 002" in season 2019.
Caspian Gull Larus cachinnans PLDP 9CY, May 07 2020, Lelystad, the Netherlands.
Parent of
"nest 005" in season 2019 and 2020. Originally, ringed as pullus in Poland.
Caspian Gull Larus cachinnans PESV 10CY, May 07 2020, Lelystad, the Netherlands.
Parent of
"nest 006" in season 2019 and 2020. Originally, ringed as pullus in Poland.
Caspian Gull Larus cachinnans XLDT adult, May 07 2020, Lelystad, the Netherlands.
Parent of
"nest 008" in season 2019 and 2020. Originally, ringed as pullus in Poland.
Ringing Caspian Gulls on May 16 2019. Visit the breakwaters by kayak.
Caspian Gull Larus cachinnans F|G 1CY, August 01 2019, Lelystad, The Netherlands (52°30'36.17"N 005°25'11.70"E). Picture: Merijn Loeve.
Bird hatched at "nest B2019"
in season 2019.
Caspian Gull Larus cachinnans F|L 2CY, April & August 2020, Lelystad, the Netherlands. Picture: Eric Roeland.
Bird hatched at
"nest 008" in season 2019
.
Caspian Gull Larus cachinnans F|D 1CY, May 16 2019. Bird hatched at "nest A2019" in season 2019.
Caspian Gull Larus cachinnans F|E 1CY, May 16 2019. Bird hatched at "nest A2019" in season 2019.
Caspian Gull Larus cachinnans "nest F2019" in season 2019. Two chicks ringed: F|N and F|P.
Caspian Gull Larus cachinnans F|N 2CY, July 29 2020, Lelystad, the Netherlands. Picture: Eric Roeland.
Bird hatched at "nest F2019" in season 2019.
Caspian Gull Larus cachinnans "nest G2019" in season 2019. A-egg hatching.