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Location Slovenia, Notranjska
Central coordinates 14o 23.00' East  45o 45.00' North
IBA criteria A1, B1i, B3, C1, C2, C6
Area 3,500 ha
Altitude 548 - 623m
Year of IBA assessment 2011

Drustvo Za Opazovanje in Proucevanje Ptic Slovenije

Site description Lake Cerknica is situated on the largest polje (karst field) in Slovenia. A temporary eutrophic lake which is usually totally dry in summer and late winter, but with an area of 2,600 ha when full in spring and autumn. There are huge expanses of reed, sedge and wet grasslands. On the eastern border of the lake, there are remnants of a raised bog. The habitats have been little affected by man. There are a few settlements along the border of the IBA, especially to the north and east, the largest being Cerknica town with 3,000 inhabitants. The lake is historically famous for its underground water system, first described in 1689.

Key Biodiversity Important numbers of the globally threatened Crex crex breed. Other species of global conservation concern that do not meet IBA criteria: Aythya nyroca (1-5 pairs, the most important breeding site in Slovenia; 10-25 birds on passage), Haliaeetus albicilla (2-5 birds feed in the area but do not breed). A total of 230 bird species have been recorded so far, of which 94 species have bred. Besides its international importance, the site has great value for nationally rare breeding species and nationally important numbers of waterbirds in winter and on passage.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Ferruginous Duck Aythya nyroca passage  2007-2011  200-600 individuals  A1, C1  Near Threatened 
Red-footed Falcon Falco vespertinus passage  2000-2009  300-1,500 individuals  A1, C1, C6  Near Threatened 
Circus cyaneus winter  2007-2009  10-50 individuals  C6  Not Recognised 
Corncrake Crex crex breeding  1992-2002  60-100 breeding pairs  C6  Least Concern 
Little Crake Zapornia parva breeding  2002-2011  10-20 breeding pairs  C6  Least Concern 
Spotted Crake Porzana porzana breeding  2002-2011  10-30 breeding pairs  C6  Least Concern 
Common Crane Grus grus passage  2007-2011  500-1,500 individuals  B1i, C2, C6  Least Concern 
Wood Sandpiper Tringa glareola passage  2000-2010  1,200-1,500 individuals  C6  Least Concern 
Ruff Calidris pugnax passage  2000-2010  1,000-1,500 individuals  C6  Least Concern 
Barred Warbler Sylvia nisoria breeding  2008  50-80 breeding pairs  B3, C6  Least Concern 

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
Cerknisko jezero z okolico (Lake Cerknica and its environs) Wetlands of International Importance (Ramsar) 7,250 protected area contained by site 7,250  
Notranjski regijski Park Regional Park 22,811 protected area overlaps with site 3,316  


IUCN habitat Habitat detail Extent (% of site)
Grassland Humid grasslands; Mesophile grasslands  30%
Wetlands (inland) Fens, transition mires and springs; Raised bogs; Rivers and streams; Standing freshwater; Water fringe vegetation  70%

Land use

Land-use Extent (% of site)
agriculture 40%
tourism/recreation 20%
not utilised 40%

Protection status National None International None

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Lake Cerknica. Downloaded from on 24/10/2016

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