St Kilda
Country
United Kingdom of Great Britain and Northern Ireland (UK)
Inscribed in
1986
Criteria
(iii)
(v)
(vii)
(ix)
(x)
The conservation outlook for this site has been assessed as "good" in the latest assessment cycle. Explore the Conservation Outlook Assessment for the site below. You have the option to access the summary, or the detailed assessment.
This volcanic archipelago, with its spectacular landscapes, is situated off the coast of the Hebrides and comprises the islands of Hirta, Dun, Soay and Boreray. It has some of the highest cliffs in Europe, which have large colonies of rare and endangered species of birds, especially puffins and gannets. The archipelago, uninhabited since 1930, bears the evidence of more than 2,000 years of human occupation in the extreme conditions prevalent in the Hebrides. Human vestiges include built structures and field systems, the cleits and the traditional Highland stone houses. They feature the vulnerable remains of a subsistence economy based on the products of birds, agriculture and sheep farming. © UNESCO
Summary
2025 Conservation Outlook
Finalised on
11 Oct 2025
Good
Current state and trend of VALUES
Low Concern
Overall THREATS
Overall PROTECTION and MANAGEMENT
Full assessment
Description of values
Significant marine and maritime plant communities
Criterion
(x)
The combination of exposure to oceanic swell, deep ocean currents along the continental slope, water depth and clarity produce a diverse range of marine communities and species of both northern and southern provenance at the extremities of their range (World Heritage Committee, 2013; StKMPlan; Posford Duvivier Environment, 2000). Unique ecological conditions also result in diverse coastal and inland plant communities and species, making the maritime grassland turf and underwater habitats integral elements of the total island setting (World Heritage Committee, 2013; StKMPlan; Love, 2009).
Significant populations and colonies of seabirds
Criterion
(x)
St Kilda supports the largest seabird colony in the north-east Atlantic, its size and diversity of global significance making it a seabird sanctuary without parallel in Europe. A number of significant populations of seabird species inhabit St Kilda including the oldest and one of the largest Northern Fulmar (Fulmarus glacialis) colonies in the UK, a significant proportion of the UK population of the Atlantic Puffin (Fratercula arctica) and one of the largest Northern Gannet (Morus bassanus) colonies in the world (World Heritage Committee, 2013; StKMPlan; Mitchell et al., 2004; Love, 2009; Murray & Wanless, 1997; Wanless et al., 2005; Murray et al., 2014).
Important seabird station
Criterion
(x)
St Kilda is one of the largest seabird sites in the North Atlantic and Europe with over half a million birds present in the breeding season (World Heritage Committee, 2013; Murray, 2002; Mitchell et al., 2004), utilizing the range of breeding sites and ecological niches offered by the local topography in combination with the rich productivity of the surrounding sea (World Heritage Committee, 2013).
Outstanding array of species in diverse terrestrial communities
Criterion
(ix)
The islands are home to an outstanding array of species in diverse terrestrial communities, including a number of endemic sub-species such as the St Kilda wren, the St Kilda fieldmouse and the St Kilda dandelion, following genetic divergence since their ecological colonisation. Additionally, the ancient breed of Soay sheep, descendents of the most primitive domestic sheep found in Europe roam the isle of Hirta (World Heritage Committee, 2013).
Complex ecological dynamic in the marine zones
Criterion
(ix)
There is also a complex ecological dynamic in the three marine zones present at the site that is essential for the maintenance of both marine and terrestrial biodiversity (World Heritage Committee, 2013). The highly diverse range of species, many of which are rare or absent elsewhere, mean that local marine communities are exceptional in terms of biodiversity value (World Heritage Committee, 2013; Posford Duvivier Environment, 2000)
Diverse seabird communities
Criterion
(ix)
Densely packed seabirds nest on cliffs in a relatively small area (World Heritage Committee, 2013; Murray, 2002; Mitchell et al., 2004). Seabirds successfully utilize the range of breeding sites and ecological niches offered by the local topography (World Heritage Committee, 2013)
Outstanding natural features and island scenery
Criterion
(vii)
The scenery of the St Kilda archipelago is spectacular, reflecting its volcanic origin and subsequent weathering and glaciation to produce a dramatic island landscape of jagged towering cliffs – some of the highest sea cliffs in Europe – and sea stacks present stark black precipitous faces plunging from steep grass green slopes. Marine erosion of the hard igneous rocks has produced cliffs extending underwater to produce dramatic sea caves, spectacular sea cliffs and stacks (World Heritage Committee, 2013).
Several endemic and near-endemic species
The isolation of St Kilda has led to a divergence among some species, which are now recognisably distinct: the St Kilda wren (Troglodytes troglodytes hirtensis), the St Kilda field mouse (Apodemus sylvaticus hirtensis) and the St Kilda dandelion (Taraxacum pankhurstianum) – only identified in 2012 (Richards and Ferguson-Smyth, 2012). Also of note are the weevil (Ceutorhynchus insularis) – currently only recorded on Dun and the Westman Islands of Iceland; the rare fly Calliphora uralensis; and 10 ichneumons (parasitic wasps), which are unique to St Kilda among the Western Isles (National Trust for Scotland, 2022).
Presence of arctic-alpine plants
St Kilda has some of the most extensive and best examples of this extreme form of Atlantic maritime vegetation in Europe, which are designated Natura 2000 plant communities by the Special Area of Conservation (SAC) designation, such as purple saxifrage (Saxifraga oppositifolia) and moss campion (Silene acaulis) (National Trust for Scotland, 2022).
Evidence of age-old traditions, land uses and built heritage features
Evidence indicates the St Kilda archipelago was occupied, perhaps continuously, for over 4,000 years until 1930 (National Trust, 2021). A recent excavation discovered pottery sherds dating back to the Iron Age and radiocarbon dating of carbonised food remains stuck to sherds of pottery indicated "intensive inhabitation" of Village Bay between the early part of the 4th Century BC to almost the end of the 1st Century BC ( BBC, 2021). Palynological investigation of artificially accreting (plaggen) soils from the settlement of Village Bay, Hirta, shows the St Kilda archipelago was perhaps the most distant outpost of sustained human habitation in the British Isles. Cultivation footprint includes evidence of peat cutting and pastoral activities (sheep and cattle) (Donaldson et al., 2009), which supplemented the community’s reliance on seabird products as their main source of livelihood (SOUV). The drystone dyking and some building forms, such as the cleits, on St Kilda are visible evidence of the skills and traditions of the community, uniquely formed by the geology, landscape and people (National Trust for Scotland, 2022). These were developed over millennia to form an exceptionally well-preserved cultural landscape.
Gaelic language intangible cultural heritage
Although the Gaelic dialect of St Kilda is no longer spoken, the Gaelic language itself is still in widespread use throughout the Western Isles, although recognised as being in a precarious position. The current management plan, includes a commitment that Gaelic will be used in the interpretation and promotion of St Kilda, to help people experience the place and lives of its inhabitants (National Trust for Scotland, 2022). The historic recordings from St Kilda of both songs and spoken word are a resource that can enrich the experience of the islands, and these should be made more widely available. The Trust’s revised Gaelic Policy and the Scottish Government’s Gaelic language plan 2022-2027 recognise the key role of language in cultural identity and offer guidelines for its appropriate use.
Assessment information
The remoteness and isolation of the St Kilda archipelago grants natural protection from direct human induced threats. As such, the existing current threats are at low levels under the current management prescriptions, with little immediate prospect of deterioration in the site values. Visitor numbers have increased in recent years, but are still within acceptable levels and easily controlled under the existing management arrangements. However, the effects of climate change on the site can be seen to be affecting multiple key attributes. Recent reports indicate significant pressure from climate change on the breeding success of seabirds, subsequent population declines and likely community and ecosystem level disruptions could occur. Whilst the threat of climate change is likely to be growing within the site the degree to which this can be mitigated at the site level is low.
Recreational Activities
(Excessive visitor pressure )
Inside site
, Localised(<5%)
Hirta is a small island with finite resources. A high volume of visitors (particularly during a short time period) could potentially affect the site in many ways: erosion, use of limited resources such as water, increased risk of introducing new invasive species and also and a modified sense of place and visitor experience / enjoyment (National Trust for Scotland, 2022). The Outer Hebrides have experienced a notable increase in leisure visitors in recent years, which is also reflected in the number of visitors to St Kilda. Visitor numbers increased by nearly 60% from the previous six years. Since 2015 (excluding 2020) the average number of visitors each year was 5,112. However, the season only runs from mid-April to mid-September with most visitors (on average 58%) arriving in the months of May and June (National Trust for Scotland, 2022).
Currently annual visitor figures have been in the region of 5500 to 6000 (IUCN Consultation, 2024). The increase is mainly due to day visitors from several small charter vessels in recent years, and to small expedition cruise ship passengers whose numbers may vary greatly. A limit on the size of cruise ships and number of landings was introduced to control pressure on island resources. This is still within acceptable levels and easily controlled under the existing management arrangements and is limited by weather conditions which may inhibit landings. Although there is no data of the impact of anchorage of large vessels on the seabed communities, it is assumed to be negative (IUCN Consultation, 2025).
Recreational diving has always been a popular pursuit around the islands but is assumed to have negligible impact and has recently declined. In recent years there have been more requests by rock climbers to scale the stacks and cliffs which would cause serious disturbance and damage to breeding Gannets, particularly on Stac Li and Stac an Armin (Murray et al., 2013). Access legislation in Scotland makes it difficult to prevent ad hoc landings on islands and stacks other than Hirta, but these are still very few and controlled by difficult/limited landing places and the weather. All access must be compliant with the Wildlife and Countryside Act, which protects nesting birds from disturbance (Scotland Act 1981) (NCC/SNH/ NS and NTS Ranger reports, WIM Reports).
Currently annual visitor figures have been in the region of 5500 to 6000 (IUCN Consultation, 2024). The increase is mainly due to day visitors from several small charter vessels in recent years, and to small expedition cruise ship passengers whose numbers may vary greatly. A limit on the size of cruise ships and number of landings was introduced to control pressure on island resources. This is still within acceptable levels and easily controlled under the existing management arrangements and is limited by weather conditions which may inhibit landings. Although there is no data of the impact of anchorage of large vessels on the seabed communities, it is assumed to be negative (IUCN Consultation, 2025).
Recreational diving has always been a popular pursuit around the islands but is assumed to have negligible impact and has recently declined. In recent years there have been more requests by rock climbers to scale the stacks and cliffs which would cause serious disturbance and damage to breeding Gannets, particularly on Stac Li and Stac an Armin (Murray et al., 2013). Access legislation in Scotland makes it difficult to prevent ad hoc landings on islands and stacks other than Hirta, but these are still very few and controlled by difficult/limited landing places and the weather. All access must be compliant with the Wildlife and Countryside Act, which protects nesting birds from disturbance (Scotland Act 1981) (NCC/SNH/ NS and NTS Ranger reports, WIM Reports).
Pathogens
(Avian influenza and other pathogens )
Inside site
, Widespread(15-50%)
Outside site
Avian influenza (H5N1) affected Great skua, puffin and gannet in 2021 and 2022. The Great skua population fell by 64%, although the gannet colony was less severely affected <5%. No cases were reported in 2023, but a few cases were noted in the late summer of 2024 (IUCN Consultation, 2024). The impact of the Covid pandemics in 2020 and 2021 meant that there were no staff deployed to monitor species or implement biosecurity measures.
Changes in Temperature Regimes, Changes in Precipitation & Hydrological Regime
(Increased frequency and intensity of storms and rainfall )
Inside site
, Throughout(>50%)
Outside site
A Climate Vulnerability Assessment was carried out in 2022 which assessed the impact of climate change on the Outstanding Universal Value of the Site (Bain et al., 2024). Whilst highlighting knowledge gaps, the assessment identified three key climate stressors: Temperature Trend, Storm Intensity and Frequency and Changing Currents. The interactions with each other and other stressors indicated the OUV vulnerability of the property was moderate (Bain et al., 2024). Having warmed by approximately 0.5°C in the past 150 years, St Kilda’s marine environment is projected to experience further ocean warming of around 1°C by 2050 and as much as 3°C by the end of century. Increased intensity and frequency of stormy weather is recognised as affecting the property and the wider marine area. Winters are projected to become wetter, both in terms of the intensity, total amount of rainfall and the number of wet days, all of which will affect the island’s surface and sub surface hydrological networks. This combination of factors will increase flooding and waterlogging resulting in the alteration of the ground conditions and potentially the island’s terrestrial ecology. Such changes would have implications for ground nesting sea birds (Blake, 2022) and sheep populations in particular. Changing currents and sea temperatures may affect the marine ecosystem with follow-on effects on food availability for nesting seabird colonies. The observed weakening of broad-scale Atlantic Meridional Overturning Circulation (AMOC) is considered likely to continue; with the potential for a mid-century collapse of the AMOC. Any breakdown of ocean circulation is likely to have substantial consequences on the marine ecosystems and severe consequences for St Kilda.
Climate related factors may also affect operational management, impacting on the deployment of staff, researchers, contractors, delivery of essential supplies and on visitor numbers, an important source of income.
Climate related factors may also affect operational management, impacting on the deployment of staff, researchers, contractors, delivery of essential supplies and on visitor numbers, an important source of income.
Biological System Management
(Grazing by feral sheep flock )
Inside site
, Scattered(5-15%)
The Soay sheep on Hirta have always fluctuated in numbers from 500 to 2000, and ahead of the periodic population crashes, the vegetation became overgrazed. The issue is subject to a very detailed study by various universities and is not thought to be a serious or long-term problem (Jewell et al., 1974; Clutton-Brock and Pemberton, 2004 and their Annual Research Reports). Annual monitoring will reveal any deleterious change immediately.
Several potential threats are identified, most of which are considered to pose low threats. There has been a recognisable decline in some breeding numbers and success of some seabird species. However this seems to be a product of impacts outside the site and by factors that appear to be multinational, even global. It is suggested that efforts are being made to address these at a governmental level but there is little firm data available at present to judge the degree of their success. A greater but long term threat would be presented by the closure of the military base making many of the current management aspirations and functions more difficult to sustain. However, the recent investment to rebuild the military base indicates a commitment to retain the facility and its associated support services for at least, if not beyond, the short to medium term. The development of biosecurity plans and their wider adoption, in addition to wider awareness within the Outer Hebrides and Scotland, has mitigated the risk of the introduction of invasive, non-native species. Plastic waste and discarded fishing equipment impact on marine life and seabirds, however the extent and impact on the OUV requires further investigation.
Fishing, Harvesting & Controlling Aquatic Species
(Overfishing out at sea and unsustainable fishing methods )
Outside site
Small scale crustacean creeling continues as it always has and is not considered to pose a threat, although there is little data on quantities or impact. Longline and trawl fishing takes place out at sea, subject to EU Fisheries Regulations. This could severely impact fish stocks and therefore food supplies for the seabirds nesting on St Kilda. Poor breeding seasons have been recorded for kittiwakes, puffins and other auks, fulmars, and Leach’s storm petrels (Murray, 2002; Mitchell et al., 2004; NTS Seabird Warden/WIM Reports).
The designation of the West of Scotland MPA in 2020 (JNCC, 2020) should mitigate against this potential threat, although as the MPA is recently established its effects are yet to be determined.
The designation of the West of Scotland MPA in 2020 (JNCC, 2020) should mitigate against this potential threat, although as the MPA is recently established its effects are yet to be determined.
Shipping Lanes
(Moored vessels going aground )
Inside site
, Localised(<5%)
Ship wrecks have occurred on and around St Kilda for hundreds of years (Love, 2009) and so far no rats have appeared on the archipelago; however, two recent incidents have caused concern – the supply vessel Elektron grounded in Village Bay, Hirta in October 2000, and a fishing boat Spinningdale was wrecked in Village Bay in February 2008. Monitoring and mitigation measures for rats/mink were refreshed and improved as a result (NCC/SNH and NTS Wardens/WIM reports, StKMPlan). A new biosecurity plan was adopted during the construction of the new MOD facility due to the increased frequency of shipping.
The National Trust for Scotland have adopted a new biosecurity plan as part of a national project for all SPAs (IUCN Consultation, 2020) as have MOD contractors QinetiQ who manage the military installation on island.
The National Trust for Scotland have adopted a new biosecurity plan as part of a national project for all SPAs (IUCN Consultation, 2020) as have MOD contractors QinetiQ who manage the military installation on island.
Water-borne & other effluent Pollution
(Oil slicks )
Inside site
, Extent of threat not known
Outside site
In December 1981 the empty 100,000 ton tanker Maersk Angus lost power temporarily and drifted perilously close to St Kilda but no spillage incident took place (Love 2009). Since the Braer went aground in Shetland in January 1993 laden tankers are encouraged to take the outside route, west of the Hebrides which renders St Kilda, vulnerable to oil spillages etc. of which a major spill could have a potentially catastrophic impact on seabirds and other marine life (StKMPlan). In 2004 two Marine Environment High Risk areas (MEHRA) were established to the north and south of St Kilda, encouraging mariners to take extra care in, or avoid, these areas.
Conflict, Civil Unrest & Security Activities
(Refurbishment of the existing MOD base and its facilities )
Inside site
, Localised(<5%)
The impact of Ministry of Defence radar tracking station buildings and some infrastructure has been present ever since this military base was established in 1958. However, refurbishment of these facilities has taken place to minimise these impacts in recent years. A new accommodation block and energy centre was completed and older buildings demolished in 2021. The new buildings occupy a smaller footprint, have a turf roof and larch cladding and are therefore more environmentally sensitive and have a correspondingly reduced impact on the site and its surrounding landscape (IUCN Consultation, 2020). Notwithstanding the improvements to the landscape character of this part of the island and given the significant financial investment to refurbish these buildings there is still a continued defence staff presence on the island. In the unlikely circumstances these existing facilities were to be decommissioned sometime beyond the short to medium term, the withdrawal of MOD staff from the site and the current support services provided by the MOD in ferrying goods and personnel to the islands, may no longer exist. That being the case current levels and standards of direct management of the site could be difficult to be maintain. Should this occur this would directly affect the opportunities site managers and volunteers would have to provide the existing range of on-site stewardship and visitor services and research opportunities. The likelihood of this happening within the near future is very low.
Invasive Non-Native/ Alien Species
(Potential introduction of invasive species )
Inside site
, Extent of threat not known
Introduction of invasive species represents a potential threat to the site's biodiversity values (IUCN Consultation, 2017). However, steps are taken whenever possible to mitigate against this potential threat. For example, in 2017 a supply vessel was refused permission to enter the WHS as it’s port of origin had an outbreak of Carpet sea-squirt, this highlighted the need for an enhanced bio-security plan to include marine species (IUCN Consultation, 2020). Biosecurity plans are in place and reviewed annually or after an incident. The Biosecurity for Scotland project ahs highlighted the issue across Scottish SPAs including St Kilda.
Changes in Temperature Regimes, Changes in Precipitation & Hydrological Regime
(Sea temperature rise)
Inside site
, Throughout(>50%)
Outside site
It is thought that climate change affecting sea temperatures and ocean circulation patterns, potentially exacerbated by overfishing, might be implicated in the declines in fish stocks and impacts on seabird breeding numbers and success. However, there is insufficient data to either assess or justify this adequately. A data logger to measure temperature and salinity was deployed in Village Bay in 2021 and 2024, however no results have been received yet (IUCN Consultation, 2025).
Renewable Energy
(Impacts of offshore wind developments )
Outside site
The current management plan (National Trust, 2022) recognises that direct threats from offshore development are largely outside the World Heritage Site and therefore beyond the Trust’s control. Whilst well-designed renewable energy development is supported, the Trust will need to work collaboratively with key stakeholders to assess each potential development on a case-by-case basis, and advocate for planning decisions that protect the OUV of the site. Notwithstanding this, the flight patterns of seabirds can be significantly influenced by light-induced attraction to and disorientation by powerful artificial light sources on marine installations even though they are located well beyond the boundary of the property. This disorientation represents a form of displacement, when birds are drawn away from foraging areas or alter their instinctive behaviours (Scottish Government, 2022).
Other Human Disturbances
(Change in the welfare status of feral sheep to domestic animals)
Inside site
, Scattered(5-15%)
Soay sheep are currently considered as feral / non domestic animals. A petition by members of the public however was submitted to the Scottish Government to change to status of the feral sheep on St Kilda, to include them under the provisions of the Animal Health and Welfare Act (Scotland) Act (2006). When the site was inscribed, Soay sheep were considered as wild animals and hence survived without any form of human intervention. This has continued to be the approach to date. In March 2025 the Scottish Government confirmed that the sheep on St Kilda would continue to be protected by the Wild Mammals (Protection) Act 1996, in the same way as any unowned and unmanaged population of wild deer are (Scottish Government Citizen Participation and Public Petitions Committee Official Report 19.03.25).
A change in management may affect the dynamics of the feral sheep population, their grazing patterns, the genetic characteristics and importance of the flock (IUCN Consultation, 2024). The population of Soay sheep is however stable / slightly increasing under the Trust's current non-interventionist approach (IUCN Consultation, 2024).
A change in management may affect the dynamics of the feral sheep population, their grazing patterns, the genetic characteristics and importance of the flock (IUCN Consultation, 2024). The population of Soay sheep is however stable / slightly increasing under the Trust's current non-interventionist approach (IUCN Consultation, 2024).
Garbage & Solid Waste
(Marine pollution)
Inside site
, Throughout(>50%)
Outside site
Plastic waste and discarded fishing equipment impact on marine life and seabirds. Plastic nurdles have been noted in Great skua pellets and in fulmar carcasses (Hammer et al., 2016). Occasional entanglements of seabirds in fishing line have been noted in the archipelago (St Kilda Ranger reports) and the use of discarded rope and other plastics is evident in gannet nests. Entanglement can cause death by inhibiting foraging and limiting movement. The impact of plastic ingestion is less well understood (IUCN Consultation, 2025).
Involvement of stakeholders and rightsholders, including indigenous peoples and local communities, in decision-making processes
There is no resident population within the property with the nearest communities located on the Outer Hebrides (45+ miles away). Consultation meetings were held locally, with further public online engagement, input and feedback from interested parties, including Councillors, during the preparation of the current Management Plan (StKMPlan National Trust, 2022; World Heritage Committee, 2013). The Management Plan has been endorsed by all key agencies and stakeholders – the Council, Ministry of Defence, NatureScot and Historic Environment Scotland (IUCN Consultation, 2020).
Legal framework
The primary legislation that protects the archipelago and surrounding seas and their key attributes are: The Conservation (Natural Habitats. & C.) Regulations 1994, as amended; The Wildlife and Countryside Act 1981; The Land Reform Act 2003; Nature Conservation (Scotland) Act 2004; The Ancient Monuments and Archaeological Areas Act 1979; The Planning etc. (Scotland) Act 2006; and The Environmental Liability (Scotland) Regulations 2009. Land tenure is secure and the site has many nature conservation designations (WHS, NNR, SSSI, SPA, SAC, NSA) most with associated legal obligations. There is sufficient capacity to employ this legislation effectively (World Heritage Committee, 2013).
Governance arrangements
The site is owned and managed by the National Trust for Scotland. Collaborative partnership arrangements and financial protocols exist with the key stakeholders. Strategic and Operational Management groups exist creating an effective and proactive working relationship between the National Trust for Scotland (NTS), and all the key stakeholders NatureScot, Historic Environment Scotland, Comhairle nan Eilean Siar and the Ministry of Defence. The Strategic Management Group (SMG) provides strategic direction, considers and advises on new policies, and maintains an overview of the management plan and its delivery, as and when required. The Operational Management Group (OMG) agrees operational work plans and co-ordinates actions planned by each member organisation to help it to deliver its respective and collective obligations. The OMG meets regularly to review progress (National Trust for Scotland, 2022).
Integration into local, regional and national planning systems (including sea/landscape connectivity)
Comhairle nan Eilean Siar, as the local planning authority, and the Scottish Government are largely supportive in management, but coordination could be improved (State Party of the UK, 2002). All infrastructure proposals and activities which may potentially have an impact on the OUVs of the property are subject to rigorous statutory Heritage / Environmental Impact Assessment procedures.
Boundaries
The boundary at low water which marks the whole archipelago is clearly defined and well recognized. However, the outer World Heritage property marine boundary is not obvious and not well known. The boundaries are therefore adequate to preserve the terrestrial values of the site, but no marine buffer zone beyond the designated WH area exists and therefore no effective legislative framework is associated with these areas of the open seas (World Heritage Committee, 2013; StKMplan).
Overlapping international designations
N/A
Implementation of World Heritage Committee decisions and recommendations
There have been no recent Committee decisions for the site. Most if not all of the management activities that can be pursued, are being implemented and monitored effectively, with the exception of the status of the marine area (State Party of the UK, 2002).
Climate action
Climate-related stress factors identified in the Climate Vulnerability Index Assessment, as well as affecting the site values directly, may also affect operational management impacting on the deployment of staff, researchers and contractors, delivery of essential supplies and on visitor numbers, the latter being an important source of revenue. The current Management Plan recognises their significance and promotes a proactive co-partnership stewardship approach which focuses further research and management objectives, priorities and adaptation and mitigation measures on those issues which will help reduce the impacts of climate change on the site’s OUVs (National Trust for Scotland, 2022).
Management plan and overall management system
The current comprehensive St Kilda World Heritage Management Plan (2022-2032) (National Trust for Scotland, 2022) is operational and fully effective in its purpose and clearly defines future management priorities. There is an excellent working relationship between National Trust for Scotland (NTS), NatureScot, Historic Environment Scotland, Comhairle nan Eilean Siar and Ministry of Defence. The Operational Management group is highly effective in that it includes all key stakeholders and meet informally on an annual basis to review progress and forward planning (StKMPlan). The overall management of the site is therefore sound and highly effective.
Law enforcement
Enforcement of the relevant laws and regulations is effective.
Sustainable finance
The available budget and their sources are laid out, administered by National Trust Scotland (mostly from rent and operator payments) and are found acceptable but still have scope for improvement so that anticipated management needs can be fully met and implemented. Finances are therefore secure in the medium term and moves are afoot to have them extended (State Party of the UK, 2002). Although the National Trust for Scotland reports that income increased by 18%, the current management plan aims to further improve financial security (National Trust for Scotland, 2022) by identifying key partnerships, more diverse income streams (e.g. philanthropy, grants, tourism, and rental and commercial income) and through maximising existing income streams– thereby reducing drawdown from the Trust’s General Income Fund (GIF).
Staff capacity, training and development
Staff training could be enhanced to improve and enhance management outputs. There is a high standard of expertise and training, but additional finance would permit full access to professionals in all disciplines and to improve research, interpretation, visitor management and administration. Equipment is well maintained and good use is made of volunteer resources and skills. The COVID-19 pandemic in 2020 had a big impact on both the Trust’s finances and the income for St Kilda. The immediate outcome of this resulted in no seasonal staff or volunteers being employed during 2020 (Natural Trust for Scotland, 2022). These circumstances demonstrated the high vulnerability of staff capacity to achieve their objectives during that period.
Education and interpretation programmes
An excellent informative museum exists, complemented by a comprehensive and attractive range of literature available and an appealing website. Other projects and exhibitions are constantly generated off site by outside or related bodies, schools etc. Social media accounts provide regular updates on day-to-day life and information on conservation (IUCN Consultation, 2020). The Trust has provided advice, information and archive material for exhibitions in Lewis, North Uist and Skye. Active participation of staff in conferences on a range of subjects, from archaeology and conservation of historic buildings to seabirds and the management of World Heritage sites is ensured. The Trust has worked with stakeholders and communities in the Western Isles with the aim of providing a range of more permanent off-site interpretation. A successful NS/Trust partnership supported a visit to St Kilda by local children, who also participated in a UNESCO Youth Summit in Greenwich. The Trust is making its archive more publicly accessible, through the digitisation of images and documents, including the 1906–09 diary of Alice MacLachlan, which is now available online (National Trust for Scotland, 2022). The St Kilda Club, established over sixty years ago, helps conserve and protect the Islands of St Kilda, and to raise funds and public awareness of St Kilda's outstanding beauty, animal and plant life, artefacts, archaeology and the buildings, culture and natural history.
Tourism and visitation management
The ranger service provides an encouraging welcome and briefing for visitors, while additional provision is made for groups with their own guides who are familiar with what is realistically on offer given the time restraints ashore. Guidelines are available stressing safety precautions etc. and tour operators are highly sympathetic to the site values and co-operative. The site is large enough and visitor impact small enough to minimize deleterious impacts to its values. The Trust recognises that collaboration is key and is working with key stakeholders to develop a sustainable tourism strategy. St Kilda is also part of Scotland’s UNESCO Trail, which unites UNESCO designated sites to promote both sustainable tourism and UNESCO values (National Trust for Scotland, 2022).
Sustainable use
Within Hirta itself the available resources are utilized effectively but difficulties of access to all the other islands and stacks limit any further exploitation, thus effectively preserving the conservation values (State Party of the UK, 2002; StKMPlan; and pers obs).
Monitoring
Terrestrial values are well monitored, especially for seabirds by the seabird ranger (sample population and productivity plots etc.) with national surveys approx. every 10 years. There are also monitoring programmes for vegetation, sheep, migrant birds and for ad hoc monitoring of lepidoptera and cetaceans. Certain groups of invertebrates, geological and geomorphological features have been surveyed but there is no regular monitoring of marine habitats and species (constrained perhaps by the physical conditions of the site) (NCC/SNH wardens reports, WIM reports, Research team reports and publications; StKMPlan; State Party of the UK, 2002). A mapping survey of marine habitats and species was carried out by SNH in 1997 and 2000 (Posford Duvivier Environment, 2000). A monitoring survey of the sea cave feature was conducted in 2015 (Harries et. al, 2018), and marine monitoring surveys for sea caves are carried out every 12 years and a review of potentially damaging activities every 6 years (IUCN Consultation, 2020). Whilst marine monitoring is limited by a combination of weather conditions and the high cost of marine monitoring surveys, there is also a relatively low probability of human-induced impacts due to St Kilda's remote location (IUCN Consultation, 2020).
Research
The earliest studies associated with St Kilda’s bird life predate the 1840s and the earliest written record of St Kilda and its inhabitants date from 1202 when an Icelandic cleric wrote about sheltering on the islands. The islands were called "Hirtir" by the Norse (Fleming, 2005). Research and studies of the bird life, life styles and the cultural heritage of the islands have been ongoing ever since. There is now an effective St Kilda research policy with its associated Guidelines (National Trust for Scotland, 2022). Together these determine whether and how to commission, coordinate and collaborate research associated with the St Kilda World Heritage Site. Research is targeted at those priorities which address the sympathetic stewardship of the site’s values and inform and improve the effectiveness of management and decision making. There is however, still scope for development and extension in the future. Research has been conducted into the impact of Great skuas Stercorarius skua on Leach’s storm petrels and on the distribution and population of the St Kilda field mouse (Apodemus sylvaticus hirtenis) as well as isotope analysis to determine their diet (Bicknell et al., 2020). Research is currently being conducted on foraging of Leach’s storm petrels and Manx shearwaters and the genetics of the St Kilda wren (IUCN Consultation, 2024). Project staff are contributing to a national research project on H5N1 – avian flu to determine exposure, immunity and transmission. The well-established research programme on the Soay Sheep of St Kilda make the population one of the best understood of its kind (Regan et al., 2020; Kentie et al., 2020; Hayward et al., 2019; etc.).
Effectiveness of management system and governance in addressing threats outside the site
With no effective marine buffer zone identified, management recommendations outwith the site and the powers of its managers to influence change in these marine areas are limited. Fishery pressure around the site including in the feeding areas of local seabirds was previously largely driven by EU policies, however it remains unclear how this will change in the present day context (State Party of the UK, 2002; StKMPlan). Wider scale environmental fluctuations have increased in recent years, likely as a result of climate change. Although these have resulted in recognisable detrimental impacts on seabird populations within the site, the impact and significance of these changes are difficult to judge and manage at a site level.
Effectiveness of management system and governance in addressing threats inside the site
The management of the site is highly effective. A ten year comprehensive Management Plan (2022-32) is in place and there is adequate monitoring of most values, although the monitoring of the marine features is carried out very rarely (IUCN Consultation, 2017).
The protection and management of the site is highly effective. Current and medium term management priorities and research are focused and guided by the objectives of the current Management Plan. These are implemented to the extent possible given the remote nature of the site and with cooperation with all the relevant stakeholders, including the Ministry of Defence. Staff are relatively well-resourced, with adequate training to deliver the objectives and clear priorities of the management plan, however additional funds could improve this situation, especially given increased visitation in recent years. The terrestrial integrity of the site is well safeguarded by effective protection and management measures and national legislation, notwithstanding some limitations arising in the marine environment beyond the property.
Good practice examples
A comprehensive Climate Vulnerability Index Assessment was undertaken in 2024. Its conclusions are embedded in the objectives and range of proactive management priorities of the current Management Plan. The CVI assessment has resulted in co-partnership stewardship approaches focusing on those adaptation and mitigation measures which will help reduce the impacts of climate change on the site’s OUVs.
Significant marine and maritime plant communities
Data Deficient
Trend
Data Deficient
Given the limited degree of baseline data available from a mapping survey for marine communities carried out in 2000 (Posford Duvivier Environment, 2000) and a proposed monitoring plan for sea cave communities (IUCN Consultation, 2020), no structured monitoring programme is in place for either marine nor coastal/maritime terrestrial systems, partly due to logistical difficulties. Therefore it is difficult to assess any change.
Significant populations and colonies of seabirds
Low Concern
Trend
Deteriorating
The site remains a stronghold for the northern gannet and still holds one of the largest colonies of the species in the world. However, populations of other seabird species have experienced consistent and medium-term population declines, evidenced by erratic breeding success with occasional complete failures in recent decades in puffins and steadily deteriorating populations trends in fulmar. Despite this, the most recent survey data suggest that such declines are stabilizing with good productivity figures in the last two years for puffins and an increase in apparently occupied sites (AOS) in northern fulmar (IUCN Consultation, 2020).
Important seabird station
High Concern
Trend
Deteriorating
Regular censuses and productivity monitoring by NTS Seabird rangers have indicated a decline in some species such as northern fulmar (Fulmarus glacialis), black-legged kittiwake (Rissa tridactyla), Leach’s storm petrel and the four species of British breeding auks (Alcidae), as well as recent additional pressure from HPAI on the internationally significant population of great skuas (IUCN Consultation, 2025).
No firm data exists on the causes of any seabird declines, however links have been established with climate change and possibly predation by Great skua (National Trust for Scotland, 2018). The site as an important breeding ground for kittiwakes (Rissa tridactyla). A census in 2016 recorded only 448 nests across the St Kilda archipelago - an 88.5% decline since a census in 1999. However, the most recent census in 2024 recorded 830 nests, giving some hope for a recovery (IUCN Consultation, 2025).
No firm data exists on the causes of any seabird declines, however links have been established with climate change and possibly predation by Great skua (National Trust for Scotland, 2018). The site as an important breeding ground for kittiwakes (Rissa tridactyla). A census in 2016 recorded only 448 nests across the St Kilda archipelago - an 88.5% decline since a census in 1999. However, the most recent census in 2024 recorded 830 nests, giving some hope for a recovery (IUCN Consultation, 2025).
Outstanding array of species in diverse terrestrial communities
Good
Trend
Stable
Whilst there is little ongoing structured monitoring of terrestrial biodiversity in the site, the active management of the site alongside the well established research program on Soay Sheep have not reported any significant decline in this value (NTS Ranger/WIM Reports; Booth, 1996; Crawley, 1993).
Complex ecological dynamic in the marine zones
Low Concern
Trend
Stable
There is a need for further monitoring but the subtidal habitats seem in a good state and there is no evidence to suggest that they have varied significantly since baseline data was obtained (Posford Duvivier Environment, 2000). There is little information, however, on the current state of marine biodiversity, especially in light of declining seabird populations being attributed anecdotally to shifting marine prey species availability in some instances (National Trust for Scotland, 2018).
Diverse seabird communities
Low Concern
Trend
Deteriorating
Despite a decline in some species, and the as yet unknown community effects of shifting population dynamics, biodiversity will likely remain uncompromised in the short to medium term (StKMPlan). There has been no obvious decline in terrestrial habitat quality, however recent report suggest a growing threat of climate change impacting seabird communities on St Kilda (StKMPlan; National trust for Scotland, 2018), however these impacts are still poorly understood.
Outstanding natural features and island scenery
Good
Trend
Stable
The scale of the features is such that little can be done to improve them. While largely in a good state, certain aspects should be addressed to improve the scenic quality at the main access point. Discussions have begun regarding the possible removal of the coastal defences and landscaping of the main access point. The rebuild of the Ministry of Defence accommodation block and energy centre was completed in the summer of 2019. Works to demolish the old buildings and reinstate the ground have likewise been completed (IUCN Consultation, 2020). Both these activities have reduced the overall footprint of this facility and considerably improved the appearance of the building and the landscape quality and character of this area of Hirta.
Assessment of the current state and trend of World Heritage values
Stable
The overall condition of the site is of low concern and stable, with a few specific issues requiring more investigation. Terrestrial biodiversity seems to be stable and of healthy status, whilst the scenic values of the site are improving through the ongoing work around buildings and infrastructure on the site. Of greatest concern is the decline in numbers and breeding success of some seabird species, however as the drivers of these are likely to be wider marine issues, the degree to which this may be addressed at the site level is low. The relative lack of data relating to the site's marine biodiversity also highlights the need for a systematic monitoring system in the coastal and inshore marine ecosystems.
Assessment of the current state and trend of other important biodiversity values
Good
Stable
St Kilda field mouse and St Kilda wren rated good and populations appear to be stable (NTS Ranger/WIM Reports). A study has been undertaken into impact of great skua on Leach’s storm petrels, with ongoing study of petrel breeding using nest boxes.
Assessment of the current state and trend of other important values
Good
Stable
Built heritage features are well managed and in good condition but are likely to become increasingly vulnerable if the frequency and intensity of storms and rainfall results in the alteration of surface and sub surface water drainage patterns and an associated increase in flow rates and volumes (Blake, 2022). The built heritage is subject to a monitoring scheme that notes condition and factors influencing change. There is an annual repair and maintenance schedule with materials and methodologies approved by HEs to maintain the authenticity of the site.
Additional information
History and tradition
The story and historical context of the former community, its unusual seabird economy, and its ultimate evacuation in 1930, is well known and contributes to the great public interest in the World Heritage site.
Sacred natural sites or landscapes
The combination of natural and cultural attributes is powerful in affording the site wilderness, heritage and iconic status. St Kilda is one of the most remote and inaccessible parts of the United Kingdom, nearly 100 miles from the mainland in the North Atlantic. The towering cliffs and impressive sea stacks, densely populated by seabirds and the landscape scattered with abandoned buildings evoke a sense of the dominance of nature and the fragility of human culture.
Outdoor recreation and tourism
Difficulties of access due to the site's remote location, expensive and limited transport, unpredictable weather, all coupled with the need to avoid facilities impacting on the very values of the site, will always impose a ceiling on the scale and impact direct tourism. Those that do visit (via cruise and charter vessels and to a lesser extent yachts) find the experience hugely rewarding. Equally those who cannot visit, can access some of the St Kilda experience indirectly at visitor centres and exhibitions in the Hebrides and elsewhere by means of media interest, online websites and through many diverse publications. Small, local charter vessels and accommodation outlets in the Hebrides benefit from the attraction of the site.
Importance for research
The important aspects of geology, marine and terrestrial biology, island biogeography and evolution, feral sheep, seabirds and mice offer outstanding opportunities for research, not least monitoring of seabirds to inform debates on fisheries and global change. More work required on little-known species e.g. especially Leach's and European storm petrel.
Contribution to education
The World Heritage site has generated a huge corpus of published material, and media interest over two centuries. Websites now make this accessible to a huge global audience.
Provision of jobs,
Tourism-related income
The National Trust for Scotland employ three staff in addition to contractors who undertake a range of work.
Local based boat operators directly employ crew.
Tourists directly contribute to the management of St Kilda through pier duties, souvenirs and camping fees. The wider local economy benefits in tourist spend on boats, accommodation and food
Local based boat operators directly employ crew.
Tourists directly contribute to the management of St Kilda through pier duties, souvenirs and camping fees. The wider local economy benefits in tourist spend on boats, accommodation and food
Increased storminess could impact on the number of days St Kilda is accessible, impacting on boat operators (Bain et al. 2024).
St Kilda immediately captures the interest and imagination of all who encounter this remote archipelago and its natural attributes (both actual and virtual). It has much to offer the world of science and politics in the way of research and education. The effective management structure between the National Trust for Scotland as owner and diverse range of other stakeholders, provides a useful model for other similar sites, while the whole package offered by St Kilda enhances the profile of its dual World Heritage status and ethos.
| № | Organization | Brief description of Active Projects | Website |
|---|---|---|---|
| 1 | Various universities since 1985. Currently led by University of Edinburgh, with collaborators at Sheffield University, University of St Andrews, Moredun Research Institute & James Hutton Institute (amongst others). | A detailed study of Soay Sheep living in the Village Bay area of Hirta. Topics of research include population dynamics, breeding strategy, genetics, grazing impact, parasites, immunity, gut microbiota, ageing and behaviour (amongst other topics). The current St Kilda Soay sheep project involves >50 researchers across at least 10 international research institutions. The project routinely monitors the weather conditions in the Village Bay area of the island, the numbers and health/fitness of the sheep living in the study area, as well as assessing infection pressures experienced by the sheep. www.soaysheep.biology.ed.ac.uk |
www.soaysheep.biology.ed.ac.uk
|
| 2 | Marine Scotland with RSPB | A study identifying foraging and resting area of Leach’s storm petrel |
https://community.rspb.org.uk/ourwork/b/science/posts/tracking-the-elusive-leach-s-storm-petrel-on-st-kilda
|
| 3 | University of Oxford (T Guilford) | Identifying flight patterns and navigation of Manx c shearwater (Puffinus puffinus) |
https://www.biology.ox.ac.uk/people/tim-guilford#tab-2775956
|
| 4 | University of Birmingham | St Kilda Wren genetics and the island syndrome |
https://www.birmingham.ac.uk/staff/profiles/gees/jezierski-micha%C5%82
|
References
| № | References |
|---|---|
| 1 |
BBC (2021) Evidence that St Kilda was inhabited 2000 years ago https://www.bbc.co.uk/news/uk-scotland-highlands-islands-55…
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| 2 |
Bain S,Day JC,Jones RH,Hyslop E, Wright KA, Davies M and Heron SF (2024) Climate Vulnerability Index Assessment for the St Kilda World Heritage Property. Edinburgh & Townsville
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| 3 |
Bicknell, A. W. J., Walker, B. W., Black, T., Newton, J., Pemberton, J. M., Luxmoore, R., Inger, R., & Votier, S. C. (2020). Stable isotopes reveal the importance of seabirds and marine foods in the diet of St Kilda field mice. Scientific Reports, 10, Article 6088. https://doi.org/10.1038/s41598-020-62672-x
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| 4 |
Blake HJ (2022) Conserving World Heritage in climate change(d) futures: Building understanding of precipitation impacts through innovative hydrological-based solutions. University of Stirling, Scotland
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| 5 |
Booth A (1996) A National Vegetation Classification Survey of Hirta and Dun. Commissioned Report to Scottish Natural Heritage, Edinburgh< Perth and Inverness.
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| 6 |
Burnell, D., Perkins, A. J., Newton, S. F., Bolton, M., Tierney, T. D., & Dunn, T. E. (2023). Seabirds Count: A Census of Breeding Seabirds in Britain and Ireland (2015-2021). Lynx Nature Books. https://lynxnaturebooks.com/product/seabirds-count/
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| 7 |
Clutton-Brock T C and Pemberton J (2004) Soay sheep: dynamics and selection in an island population. Cambridge University Press (Annual Research Reports also produced, distributed by J Pemberton, University of Edinburgh)
|
| 8 |
Crawley M (1993) The Flora of St Kilda. Unpublished. Imperial College, Silwood Park.
|
| 9 |
Donaldson M.P., Edwards K.J. Mehang A.A,. Deacon C. Donaldson D.A. (2009) Land use history of Village Bay, Hirta, St Kilda World Heritage site: A palynological investigation of plaggen soils. Review of Palaeobotany and Palynology, Voulme153, Issues 1-2, https://www.sciencedirect.com/science/article/abs/pii/S0034…
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| 10 |
Fleming A. (2005) St Kilda and the Wider World: Tales of an Iconic Island, Oxbow Books, Windgather Press, Barnsley
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| 11 |
Hammer, Sjurdur & Nager, R.G. & Johnson, Paul & Furness, Robert & Provencher, Jennifer. (2016). Plastic debris in great skua (Stercorarius skua) pellets corresponds to seabird prey species. Marine Pollution Bulletin. 103. 10.1016/j.marpolbul.2015.12.018.
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| 12 |
Harries, D.B., Moore, C.G., Porter, J.S., Sanderson, W.G., Ware, F.J. & Kamphausen, L. (2018). The establishment of site condition monitoring of the sea caves of the St Kilda and North Rona Special Areas of Conservation with supplementary data from Loch Eriboll. Scottish Natural Heritage Research Report No. 1044.
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| 13 |
Harries, D.B., Moore, C.G., Porter, J.S., Sanderson, W.G., Ware, F.J. & Kamphausen, L. (2018). The establishment of site condition monitoring of the sea caves of the St Kilda and North Rona Special Areas of Conservation with supplementary data from Loch Eriboll. Scottish Natural Heritage Research Report No. 1044.
|
| 14 |
Hayward, A., Pilkington, J.G., Wilson, K., McNeilly T. and Watt, K. (2019). Reproductive effort influences intra-seasonal variation in parasite-specific antibody responses in wild Soay sheep. Functional Ecology, 33, pp.1307-13. doi.org/10.1111/1365-2435.13330
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| 15 |
IUCN Consultation (2024). Confidential consultation on St. Kilda World Heritage site.
|
| 16 |
IUCN Consultation. (2017). IUCN Confidential Consultation- St Kilda, UK.
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| 17 |
IUCN Consultation. (2020). IUCN Confidential Consultation- St Kilda, UK.
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| 18 |
JNCC. (2020). West of Scotland MPA. [online] Joint Nature Conservation Committee, Peterborough. Available at: https://jncc.gov.uk/our-work/west-of-scotland-mpa/ (Accessed 20 November 2020).
|
| 19 |
Jewell P A, Milner C and Boyd, J M (1974) Island Survivors: the ecology of the Soay Sheep of St Kilda. Athlone Press, London (out of print)
|
| 20 |
Kentie, R, Clegg, S.M., Tuljapurkar, S., Gaillard, J-M. and Coulson, T. (2020). Life‐history strategy varies with the strength of competition in a food‐limited ungulate population. Ecology Letters. doi.org/10.1111/ele.13470
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| 21 |
Love J A (2009) A Natural History of St Kilda Birlinn, Edinburgh (Comprehensive reference list)
|
| 22 |
Mitchell P I, Newton S F, Ratcliffe N and Dunn T El (2004) Seabird Populations of Britain and Ireland. Christopher Helm, London.
|
| 23 |
Murray S & Wanless S (1997) The status of the gannet in Scotland in 1994-95. Scottish Birds v19
|
| 24 |
Murray S (2002) Birds of St Kilda. Scottish Birds Supplement, Scottish Ornithologists Club, Aberlady
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| 25 |
Murray S (2014) St Kilda cetacean records 2001-2010. Unpublished report to NTS, Inverness
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| 26 |
Murray S Wanless S & Harris M P (2013) Timing of breeding and estimated fledging dates of Gannets at St Kilda in 2012. Scottish Birds v33
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| 27 |
Murray S, Wanless S & Harris M P (2014) NW Scotland Gannet Surveys in 2013. Scottish Birds v34 (includes latest St Kilda figures)
|
| 28 |
NCC/RSPB Wardens’ Reports. Unpublished, Scottish Natural Heritage archives, Edinburgh.
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| 29 |
National Trust for Scotland Western Isles Manager (WMI) Reports, Balnain House, Inverness.
|
| 30 |
National Trust for Scotland, (2021), St Kilda World Heritage Site Management Plan (2022-2032), Edinburgh https://ntswebstorage01.blob.core.windows.net/nts-web-asset…
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| 31 |
National Trust for Scotland. (2018). A million seabirds, but for how long? [online] Available at: https://www.nts.org.uk/stories/a-million-seabirds-but-for-h… (Accessed 15 April 2020).
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| 32 |
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| 33 |
Regan, C.E., Pemberton, J.M., Pilkington, J.G., Smiseth, P.T., Wilson, A.J. (2020). Linking genetic merit to sparse behavioral data: behaviour and genetic effects on lamb growth in Soay sheep. Behavioral Ecology 31:114-122. doi.org/10.1093/beheco/arz166
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| 34 |
Richards, A J; Ferguson-Smyth, C C (2012). "Taraxacum pankhurstianum(Asteraceae), a new dandelion endemic to St Kilda, Outer Hebrides, Scotland". New Journal of Botany. 2 (1): 16–19.
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| 35 |
Scottish Government, (2022) A review to inform the assessment of the risk of collision and displacement in petrels and shearwaters from offshore wind developments
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| 36 |
State Party of the United Kingdom. (2002). Report of the State Party to the World Heritage Committee on the state of conservation of St Kilda (United Kingdom). [online] State Party of the UK. Available at: https://whc.unesco.org/en/list/387/documents/ [Accessed 17 April 2020].
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| 37 |
Wanless S Murray S & Harris MP (2005) The northern gannet in Britain and Ireland in 2003-04. British Birds v 98
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| 38 |
World Heritage Committee (2013). Decision: 37 COM 8E St Kilda Adoption of Retrospective Statement of Outstanding Universal Value (United Kingdom). In: Decisions Adopted by the World Heritage Committee at its 37th Session. [online] Paris, France: UNESCO World Heritage Centre. Available at: https://whc.unesco.org/en/list/387/documents/ [Accessed 17 April 2020].
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