St Kilda

IBA Criteria

Year of most recent IBA criteria assessment: 2007

Populations of IBA trigger species
Species Current IUCN Red List Category Season Year(s) of estimate Population estimate IBA Criteria Triggered
Leach's Storm-petrel Hydrobates leucorhous VU breeding 1999 45,433 breeding pairs B1i, B2, C2, C6
Northern Fulmar Fulmarus glacialis LC breeding 1999 68,448 breeding pairs A4ii, B1ii, C3
Northern Gannet Morus bassanus LC breeding 1999 61,340 breeding pairs A4ii, B1ii, B2, C3
Great Skua Catharacta skua LC breeding 1999 168 breeding pairs A4ii, B1ii, B3, C3
Atlantic Puffin Fratercula arctica VU breeding 1999 143,264 breeding pairs A4ii, B1ii, B2, C3
Razorbill Alca torda LC breeding 1999 1,689 individuals B3
A4iii Species group - seabirds n/a breeding 1999 341,941 breeding pairs A4iii, C4

Note: This table presents the IBA criteria triggered and the species that triggered then at the time of assessment, the current IUCN Red List category may vary from that which was in place at that time.

For more information about the IBA assessment process and criteria please click here

IBA Monitoring

Most recent IBA monitoring assessment
Year of assessment Threat score (pressure) Condition score (state) Action score (response)
2007 high unfavourable high
Was the whole site covered? Yes State assessed by Population
Accuracy of information good

Threats to the site (pressure)
Threat Level 1 Threat Level 2 Timing Scope Severity Result
Climate change and severe weather habitat shifting and alteration happening now whole area/population (>90%) slow but significant deterioration high

Condition of key/trigger populations (state)
Scientific Common TargetPop ActualPop Units Remaining Result
Hydrobates leucorhous 3200 45433 breeding pairs 100 favourable
Fulmarus glacialis Northern Fulmar 63000 68448 breeding pairs 100 favourable
Morus bassanus Northern Gannet 60500 61340 breeding pairs 100 favourable
Catharacta skua Great Skua 145 168 breeding pairs 100 favourable
Fratercula arctica Atlantic Puffin 130000 143264 breeding pairs 100 favourable
Alca torda Razorbill 3821 1689 individuals 45 unfavourable
Species group - seabirds A4iii 275738 341941 breeding pairs 100 favourable

Conservation actions taken at site (response)
Conservation Designation Management Planning Conservation Action Result
Whole area of site (>90%) covered by appropriate conservation designation A comprehensive and appropriate management plan exists that aims to maintain or improve the populations of qualifying bird species The conservation measures needed for the site are being comprehensively and effectively implemented high
For more information about IBA monitoring please click here

IBA Protection

Protected Area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)
St Kilda Site of Special Scientific Interest (UK) 870 protected area overlaps with site 853
St Kilda Marine Protected Area (OSPAR) 0 protected area overlaps with site 0
St Kilda Special Protection Area (Birds Directive) 29,015 protected area contains site 860
St Kilda Marine Protected Area (OSPAR) 0 protected area overlaps with site 0
St Kilda World Heritage Site (natural or mixed) 24,201 protected area contains site 860
St Kilda National Nature Reserve 872 protected area overlaps with site 853
St Kilda Site of Community Importance (Habitats Directive) 25,468 protected area contains site 860
St Kilda National Scenic Area 6,966 protected area contains site 0
St Kilda UNESCO-MAB Biosphere Reserve 865 is identical to site 860


IUCN Habitat Habitat detail Extent (% of site)
Shrubland Heathland -
Grassland Humid grasslands -
Coastline Rock stacks and islets -
Artificial/Terrestrial Other urban and industrial areas -
Marine Coastal/Supratidal -
For further information about the habitat classification please click here.

Land use

Land-use Extent (% of site)
military -
nature conservation and research -
For further information about the land use classification please click here.

Recommended citation
BirdLife International (2023) Important Bird Areas factsheet: St Kilda. Downloaded from on 05/02/2023.