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Location Finland, Länsi-Suomen lääni
Central coordinates 22o 11.00' East  61o 5.00' North
IBA criteria A1, A4i, B1i, C1, C2, C3
Area 2,759 ha
Altitude 41 m
Year of IBA assessment 2000


Site description Two adjacent large lakes lying south-east of Eura. Köyliönjärvi lake is 10 km long, eutrophic and surrounded by farmland and settlements. Several large ridge-like islands with mixed habitats stand in the middle of the lake. Cattle graze some parts of the shoreline keeping meadow vegetation low and deciduous forests open. The IBA also includes some of the most ornithologically important bays of Pyhäjärvi lake, which is otherwise nutrient-poor, (oligotrophic) and unimportant for birds.

Key Biodiversity One of the most important staging areas for Mergus merganser (in autumn) in Finland. Species of global conservation concern that do not meet IBA criteria: Haliaeetus albicilla (5 individuals, passage), Crex crex (1 pair, breeding).

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Whooper Swan Cygnus cygnus passage  1997  400 individuals  medium  B1i, C2  Least Concern 
Goosander Mergus merganser passage  1997  3,000 individuals  medium  A4i, B1i, C3  Least Concern 
Red-necked Grebe Podiceps grisegena breeding  1997  101 breeding pairs  medium  B1i, C3  Least Concern 
White-tailed Sea-eagle Haliaeetus albicilla winter  1997  10-15 individuals  A1, C1  Least Concern 

IBA Monitoring

2010 high unfavourable low
Good - based on reliable and complete / representative data

Human intrusions and disturbance recreational activities happening now some of area/population (10-49%) slow but significant deterioration medium
Pollution agricultural & forestry effluents - nutrient loads happening now majority/most of area/population (50-90%) slow but significant deterioration high
Residential and commercial development housing and urban areas happening now majority/most of area/population (50-90%) slow but significant deterioration high

Podiceps grisegena Red-necked Grebe 100 65 breeding pairs 65 unfavourable

Some of site covered (10-49%)  No management planning has taken place  Substantive conservation measures are being implemented but these are not comprehensive and are limited by resources and capacity  low 


IUCN habitat Habitat detail Extent (% of site)
Forest Broadleaved deciduous woodland; Mixed woodland  -
Wetlands (inland) Standing freshwater  80%
Rocky areas   -
Artificial - terrestrial   -

Land use

Land-use Extent (% of site)
agriculture 90%
forestry 10%
military 5%
water management 80%
fisheries/aquaculture -

Protection status National None International Partial689 ha of IBA covered by Special Protection Area (Köyliönjärvi).

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Köyliönjärvi and Pyhäjärvi lakes. Downloaded from on 25/10/2016

To provide new information to update this factsheet or to correct any errors, please email BirdLife