Larus cachinnans in the Netherlands

(last update: December 24, 2021)

Albert de Jong
Leon Kelder
Roland-Jan Buijs
Thijs Horst
Merijn Loeve
Mars Muusse


Cachinnans breeding in the Netherlands - project information

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please send in your observations of colour ringed birds to:

Initiation of this project

Over the last two decades, Caspian Gull showed increasing numbers of wintering and summering birds in the Netherlands, and finally had it's first breeding record in 2012. It was a 4CY male which raised at least one chick with a female Herring Gull at an inland dam construction near Amerongen, along river Rhine. The same pair was present in season 2013, but the nest failed.

In 2014, what seemed to be the first pure pair of Caspian Gull was observed at the manufactured sandy isle 'De Kreupel' in lake IJsselmeer. And again, in breeding seassons 2015-2017 there were single pairs breeding at different locations along rivers in the eastern part of the country, but as far as we know, all nests failed. Most of the breeding birds involved sub-adult males, which may have been one of the reasons for the low success rate.

Meanwhile, a few pair of Caspian Gulls started nesting in a colony of large gulls on breakwaters near Lelystad, at lake IJsselmeer. In 2016, at least three pairs were discovered among ca. 200 pairs of Lesser-Black Backed Gulls and over 40 pairs of Herring Gulls (Boele et al. in series 2014-2020).

Over the next couple of years, the colonies at De Kreupel & Lelystad increased and from 2019 on, we decided to monitor them more intensely. Leon Kelder has coordinated De Kreupel, Albert de Jong and Mars Muusse became coordinators for Lelystad; both colonies fall under Buijs Ringing Programme, and observers are kindly requested to send in observations to .

For Lelystad, visits to the breakwaters in 2019, and detailed observations of the breeding birds from a kayak revealed at least 12 nests of pure Caspian Gull couples and one nest of Caspian Gull x Herring Gull. In the same lake system, four pairs were seen on isle 'De Kreupel' in 2019, but actually numbers may have been much higher.
Within the Netherlands, at least three other locations held several nesting Caspian Gulls, including a hybrid pair of a 4CY male Caspian Gull x adult female Lesser Black-Backed Gull, which produced three fledglings.

Obviously, Caspian Gulls have established a small but growing population in the Netherlands now. In breeding season 2020, lake IJsselmeer accounted for at least 42 nesting pairs, including some mixed pairs with Herring Gull, but in general most nest looked fine for pure Caspian x Caspian Gull parents.
Interestingly, some of the breeding birds involved had been ringed as chicks in Poland (Babice and Paczków) and in the eastern part of Germany (Gräbendorfer See), showing natal dispersal of 600-850 km.

To get a better understanding of the phenotypic characteristcs in the Dutch population, and to monitor the future choice of nest locations of Dutch hatched chicks, we started a ringing scheme in 2019. Already, these ringed birds showed up abroad, with foreign recoveries of juveniles in the UK (Norfolk) and the Atlantic coast of France, Spain and Portugal.

The future will tell if they will become breeders at Dutch colonies again, or whether they make a next leap, and maybe will start breeding even further west, like in the U.K.? Below we summarise the main goals for our project.


Comparative research of Caspian Gull (CG), Herring Gull (HG) and Lesser Black-backed Gull (LBBG)

  1. Project information
    • Goals
    • Coordination
  2. Population trends
    • 1990 – 2020 international breeding numbers
    • 1990 – 2020 Netherlands observations
      • Winter
      • Summer
    • Breeding numbers at Kreupel / Lelystad CG, HG, LBBG
    • Emigration breeding birds
    • Immigration breeding birds
  3. Breeding site characteristics
    • Location
    • Nest location substrate and vegetation (shelter and cover)
    • Nearby human activities & impact
    • Background information on trap fishing and by-catches
    • Suggestions for management of the location
  4. Breeding ecology
    • Age of settlers / prospectors   
    • Breeding density in colony
    • Egg laying date
      • Water test
      • Incomplete clutches in early stage
      • Hatching chicks
    • Departure date of colony after breeding
    • Non breeding decision – floaters  
    • Site fidelity of individuals time series
    • Partner fidelity of individuals time series  
    • Dynamics between-species, sympatric breeding
  5. Fecundity
    • clutch size & volume comparing CG-HG-LBBG
    • hatching rate
    • chick growth rate
    • cannibalism
    • Observations of fletched juveniles in colony late summer
    • Mortality / survival rate - ringed juveniles become breeders
  6. Food choice
    • Pellets – prey type
    • Food left-overs around nest
    • Shifting resources with chick age
    • Feeding locations
  7. Behaviour after breeding
    • Ring readings in winter – dispersal
    • Food resources in winter
    • After breeding food competition


  1. Survey of all breeding pairs
    • Composition of the colony, species and numbers involved
    • Population trends
    • Indication of origin
    • Breeding success – determine factors
  2. Trap and ring breeding Caspian Gulls
    • Check for phenotypic characteristics
    • Age of breeding birds
    • Fidelity to nest site
  3. Trap and ring chicks
    • Fidelity to natal colony
    • Estimate growth rate of colony
    • Emigration to other nest locations
  4. Food
    • Research on pellets
  5. Management
    • Maintenance of construction work, vegetation, and structures
    • Disturbance of breeding birds
    • Publish in annual report

Boele et al. in series:
Boele A., van Bruggen J., Hustings F., Koffijberg K., Vergeer J.W. & Plate C.L. 2014. Broedvogels in Nederland in 2012. Sovon-rapport 2014/13. Sovon Vogelonderzoek Nederland, Nijmegen.
Boele A., van Bruggen J., Hustings F., Koffijberg K., Vergeer J.W. & van der Meij T. 2015. Broedvogels in Nederland in 2013. Sovon-rapport 2015/04. Sovon Vogelonderzoek Nederland, Nijmegen.
Boele A., van Bruggen J., Hustings F., Koffijberg K., Vergeer J.W. & van der Meij T. 2016. Broedvogels in Nederland in 2014. Sovon-rapport 2016/04. Sovon Vogelonderzoek Nederland, Nijmegen.
Boele A., van Bruggen J., Hustings F., Koffijberg K., Vergeer J.W. & van der Meij T. 2017. Broedvogels in Nederland in 2015. Sovon-rapport 2017/04. Sovon Vogelonderzoek Nederland, Nijmegen.
Boele A., van Bruggen J., Slaterus R., Vergeer J.W. & van der Meij T. 2018. Broedvogels in Nederland in 2016. Sovon-rapport 2018/01. Sovon Vogelonderzoek Nederland, Nijmegen.
Boele A., van Bruggen J., Hustings F., Koffijberg K., Vergeer J.W. & van der Meij T. 2019. Broedvogels in Nederland in 2017. Sovon-rapport 2019/04. Sovon Vogelonderzoek Nederland, Nijmegen.
Boele A., van Bruggen J., Hustings F., van Kleunen A., Koffijberg K., Vergeer J.W. & van der Meij T. 2020. Broedvogels in Nederland in 2018. Sovon-rapport 2020/07. Sovon Vogelonderzoek Nederland, Nijmegen.

In the 2010's, gulls were observed nesting near Lelystad. Inland colonies of Herring Gull and Lesser Black-backed Gull (dominance) are not rare in the Netherlands.
Already in 2016, Caspian Gulls were breeding at breakwaters near Lelystad harbour. Early 2019, Albert de Jong visited this location, and imagine his utterly astonishment and disbelieve, when he saw Caspians Gull flying around just everywhere he looked.
Yellow-legged Gull michahellis has been known breeding in the Netherlands for decades. However, the strong increase in Europe of the species in the 1990's never really materialised in our country. Still, it's not rare to find single birds in colonies, especially along the major water systems, often in mixed breeding. Here at Lelystad, a male Yellow-legged Gull seems to bond to 8CY female Herring Gull argenteus 97.
Checking the guarding gulls at the breakwaters, Albert estimated this colony already reached double figures for the breeding species in 2019, and quite fascinating: "You could hear the striking call just everywhere!".
Some breeding pairs use old Spoonbill nests.
By far the dominant species in colony Lelystad: Lesser Black-backed Gull. In future, we like to monitor long term trends and the interaction between Herring, Lesser Black-backed and Caspian Gulls in this mixed colony.
Breeding in good numbers here as well: Spoonbills.
Albert de Jong, coordinator for Larus cachinnans project at Lelystad, the Netherlands (52°30'36.17"N 005°25'11.70"E).
Leon Kelder, coordinator for ringing and monitoring the Caspian Gull at De Kreupel.
Roland-Jan Buijs, Dutch ringer, using tibia rings in his projects. All observations of tibia ringed birds can be sent to .
Thijs Horst with two large chicks in June, at colony Lelystad, the Netherlands (52°30'36.17"N 005°25'11.70"E).
Merijn Loeve photographing ringed birds in flight in a feeding frenzy at colony Lelystad, the Netherlands (52°30'36.17"N 005°25'11.70"E).
Mars Muusse monitoring Caspian Gulls at Lelystad.


C. J. Camphuijsen



Occurrence of Caspian Gulls Larus cachinnans along the Dutch coastline (in Dutch)

Klaas van Dijk

IN: Sula 2015
The breeding biology of Herring and Lesser Black-backed Gulls on Texel, 2006-2010.
Camphuysen & Gronert, 2010.

Intra population polymorphism of Caspian gull (Larus cachinnans) from the North-Western Coast of the Azov Sea (oological aspect).
Y.Y. Dubinina, A.I. Koshelev, V.A. Koshelev.