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Location Finland, Etelä-Suomen lääni
Central coordinates 23o 34.00' East  59o 46.00' North
IBA criteria A1, A4i, B1i, B2, B3, C1, C2, C6
Area 32,666 ha
Year of IBA assessment 2000


Site description A large archipelago on the eastern side of the Hanko peninsula. Hundreds of islands dominate the landscape, several of which are very large and forested, though most are small and rocky with very sparse vegetation.

Key Biodiversity An important area for island-breeding birds with the largest populations of Sterna caspia and Larus marinus in Finland.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
White-tailed Sea-eagle Haliaeetus albicilla winter  1994  20-30 individuals  medium  A1, C1  Least Concern 
Mew Gull Larus canus breeding  1994  800-1,000 breeding pairs  medium  B2  Least Concern 
Great Black-backed Gull Larus marinus breeding  1994  130-160 breeding pairs  medium  B3  Least Concern 
Caspian Tern Hydroprogne caspia breeding  1994  115 breeding pairs  good  A4i, B1i, B2, C2, C6  Least Concern 
Black Guillemot Cepphus grylle breeding  1994  120 breeding pairs  good  B2  Least Concern 

IBA Monitoring

2010 medium unfavourable medium
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
Invasive & other problematic species, genes & diseases invasive non-native/alien species/diseases - unspecified species happening now some of area/population (10-49%) slow but significant deterioration medium

Larus marinus Great Black-backed Gull 130 70 breeding pairs 54 not assessed
Hydroprogne caspia Caspian Tern 170 170 breeding pairs 100 favourable
Cepphus grylle Black Guillemot 120 65 breeding pairs 55 unfavourable

Most of site (50-90%) covered (including the most critical parts for important bird species)  A management plan exists but it is out of date or not comprehensive  Substantive conservation measures are being implemented but these are not comprehensive and are limited by resources and capacity  medium 

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
Ahlglon luonnonsuojelualue Private Nature Reserve 780 unknown 0  
Busön luonnonsuojelualue Private Nature Reserve 13 unknown 0  
Gästansin Luonnnonsuojelualue Private Nature Reserve 123 unknown 0  
Hättön luonnonsuojelualue Private Nature Reserve 443 unknown 0  
Hummelskärin luonnonsuojelualue Private Nature Reserve 15 unknown 0  
Lill-Skälön luonnonsuojelualue Private Nature Reserve 120 unknown 0  
Nothamnin luonnonsuojelualue Private Nature Reserve 3,528 unknown 0  
Strömsön luonnonsuojelualue Private Nature Reserve 334 unknown 0  
Tammisaaren Saariston kansallispuisto National Park 5,487 protected area contained by site 6,173  
Tammisaari and Inkoo western archipelago Baltic Sea Protected Area (Helcom) 58,550 protected area overlaps with site 23,886  


IUCN habitat Habitat detail Extent (% of site)
Sea   80%
Coastline   5%

Land use

Land-use Extent (% of site)
hunting -
military -
tourism/recreation -

Protection status National Partial International Partial6,173 ha of IBA covered by National Park (Tammisaaren Saaristo, 6,173 ha). 5,360 ha of IBA covered by Protected Area on Private Lands (Hättö, 442 ha; Hummelskär, 14 ha; Strömsö, 334 ha; Gästans, 124 ha; Lill-Skälö, 119 ha; Busö, 134 ha; Nothamn, 3,544 ha; Ahlglo, 786 ha). 25,132 ha of IBA covered by two Special Protection Areas (Tammisaaren ja Hangon saaristo; Inkoon saaristo).

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Tammisaari and Inkoo western archipelago. Downloaded from on 22/10/2016

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