Larus cachinnans in Poland

(last update: August 01, 2021)

Coordinator:
Marcin Przymencki
Klaudia Litwiniak
Mars Muusse

Home

Caspian Gull cachinnans: Mietków Reservoir & Chwałów


Mietków Reservoir & Chwałów: 50°57’04.1″N 16°36’06.5″E.

coordinators:
Paweł Grochowski,
Joanna Pomorska-Grochowska,
Klaudia Litwiniak,
Marcin Przymencki
For questions mail to: merula@wp.pl, marcin.przymencki@wp.pl

Habitat: 

Mietków is a dam reservoir on Bystrzyca river, located at Świdnicka Plain in SW Poland (Lower Silesia voivodeship), about 45 kilometres south-east of Wrocław. Nearest towns and villages are Mietków, Borzygniew, Domanice, Chwałów, Imbramowice, Maniów and Maniów Mały. It is the largest water reservoir in the area.

The construction was finished in 1986. In 2007 the Minister of Environment of Poland established Mietków Reservoir as the Special Protection Area based on Birds Directive in the law of European Union (PLB020004). This protects birds like Black-headed Gull, Mediterranean Gull, Common Tern and Shelduck.

Gulls started nesting here on a few gravel islands covered by grass and willows, although on some islands the vegetation includes higher trees as well (alders). The islands are located in south-western part of the reservoir, near the Bystrzyca river mouth. From year to year, the number of islands with gull colonies varies, mainly due to changing water level in the reservoir.

Breeding species:

  • Larus cachinnans
  • Larus michahellis
  • Chroicocephalus ridibundus
  • Ichthyaetus melanocephalus

Caspian Gulls have bred here since 1998. In the early years, a few pairs of Herring Gulls started breeding too, but abandoned the location soon. Nowadays the number of breeding pairs varies, but on average there are 200 pairs. Dominant species is Caspian Gull, but some Yellow-legged Gulls breed here too, although exact numbers are not known due to difficult conditions to observe the colony. We suppose 2-5 birds with michahellis phenotype to breed here every year, usually in mixed pairs. There were some cases of breeding Lesser Black-backed Gulls here too: in 2009 and 2010 they formed mixed pairs with Caspian Gull and Yellow-legged Gull, and in 2021 the first ‘pure’ pair of Lesser Black-backeds started a nest.

Black-headed Gulls breed in vast numbers, counts exceed the 3,000, and here and there Mediterranean Gulls have their nests. both species usually nest on the same island with the large gulls. At Chwałów pond, one pair of Mew Gulls Larus canus breeds every year.

Paper on breeding biology at Mietków.

Annual numbers for Mietków Reservoir:

year pairs ringed
2021 433 185
2020 190 233
2019 260 163
2018 230 290
2017 250 245
2016 + 17

Recovery map for Mietków Reservoir:

Location:
Mietków Reservoir & Chwałów in SW Poland.

Active map with colonies.
Caspian Gull cachinnans PLG DN 25430 1CY, August - October 2011, Deponie Pohlsche Heide - Minden, Germany. Picture: Armin Deutsch.
Caspian Gull type Larus cachinnans sensu lato PLG DN 25436 2CY-3CY, July - August 2012 & February 2013, Deponie Pohlsche Heide - Minden, Germany. Picture: Armin Deutsch.

Possibly with Yellow-legged Gull influences.
Caspian Gull cachinnans PLG DN 25463 2CY, March 22 2012, Deponie Pohlsche Heide - Minden, Germany. Picture: Armin Deutsch.
Caspian Gull cachinnans 5P45 5CY, January 29 - February 03 2009, CET Champteussé-sur-Baconne, France. Picture: Alain Fossé.
Caspian Gull cachinnans 5P56 adult, August 13 2007 & August 11 2009, Mur de Lixhe, Belgium. Picture: Charly Farinelle.
Caspian Gull cachinnans 062P 4CY, February 10 2009, Bishop's Cleeve landfill site, UK. Picture: John Sanders.
Caspian Gull cachinnans 689P 3CY, October 10 2018, Katwijk, the Netherlands. Picture: Mars Muusse.
Caspian Gull cachinnans P:C00 4CY, September & October 2020, IJmuiden & Langevelderslag strand, the Netherlands. Picture: Mars Muusse.
Caspian Gull cachinnans P:C46 5CY, June 11 2021, Mietków, Poland. Picture: Marcin Przymencki.
Caspian Gull cachinnans P:C96 2CY, September 25 2018, Westkapelle, the Netherlands. Picture: Mars Muusse.
Caspian Gull cachinnans P:D79 2CY, October 10 2018, Katwijk, the Netherlands. Picture: Mars Muusse.

Caspian Gull cachinnans P:S66 1CY, October 22 2018, Katwijk, the Netherlands. Picture: Mars Muusse.

Could this be a hybrid?

Caspian Gull cachinnans P:T16 3CY, October 02 2020, IJmuiden beach, the Netherlands. Picture: Mars Muusse.


Mediterranean Gull (Ichthyaetus melanocephalus) PEE5 adult, March 09 2020, Boulogne-sur-Mer, NW France. Picture: Mars Muusse.