b. Comparative analysis

Natural Heritage

Comparative analysis of rare or possibly unique sites is inherently difficult, particularly when comparing sites from different biogeographical realms. St Kilda possesses outstanding natural heritage values by virtue of its physical nature (landforms, geomorphological processes) and its biology (seabird colonies, species isolation, submarine communities). The physical and biological character of St Kilda is founded upon its island character where terrestrial, coastal and marine processes work together to produce a unique environment. The relative remoteness of this and other similar island groups serves to isolate biological populations, limit human interference in natural systems and help to maintain a high level of authenticity and integrity.

Comparative analysis with other global sites relies upon the identification of individual features on St Kilda and their comparison with similar features found at other sites. The nature of St Kilda, and the other island World Heritage Sites referred to here, results from an assemblage of biological and physical features that together make each site a special place. For the purposes of this document, the starting point for comparative analysis of St Kilda with other World Heritage Sites is the 1997 review prepared by Thorsell, Levy and Sigaty (A global overview of wetland and marine protected areas on the world heritage list).Thorsell et al. (1997) recognise the special significance of island World Heritage Sites. Table 2.1 in this document lists and briefly describes 16 island World Heritage Sites. Of these, six (highlighted in the table) are directly relevant to understanding the significance of St Kilda at the global level.

  France Cape Girolata, Cape Porto, Scandola Natural Reserve, and the Piano Calanches in Corsica 1983 ii, iii, iv 12,000ha The site has a typical marine fauna for the Mediterranean and contains a diverse pelagic, sedentary and migrant fauna.
  UK St Kilda 1986 iii, iv 853ha (24,201ha if extended) Seabird colonies, ongoing marine and coastal processes, seabed communities.
  SEYCHELLES Aldabra Atoll 1982 ii, iii, iv 35,000ha The atoll constitutes a refuge for the giant tortoise and flightless bird populations as well as a substantial marine turtle-breeding population and large seabird colonies.
  INDONESIA Ujung Kulon National Park 1991 iii, iv 123,051ha Coastal coral reef environment and important bird species.
  PHILLIPENES Tubbataha Reef Marine Park 1993 ii, iii, iv 33,200ha Diverse coral reef system with diverse bird species.
  UK Henderson Island 1988 iii, iv 3,700ha Coral reef with important bird populations.
  SOLOMON ISLANDS East Rennell 1998 ii 37,000ha The world’s largest raised coral atoll. High level of endemism for animal and bird species.
  AUSTRALIA Fraser Island 1992 ii, iii 166,283ha Fraser Island is the largest sand island in the world.
AUSTRALIA Lord Howe Island Group 1982 iii, iv 136,300ha Large populations of breeding seabirds with surrounding marine area showing an unusual mixture of temperate and tropical organisms.
UK Gough Island Wildlife Reserve 1995 iii, iv 6,500ha The least disturbed major cool-temperate island ecosystem in the South Atlantic Ocean, and has one of the most important seabird colonies in the world.
AUSTRALIA Heard and McDonald Islands 1997 i, ii 38,800ha + sea area Volcanically active, illustrates ongoing geomorphic processes and glacial dynamics in coastal and submarine environment, with sub-Antarctic fauna and flora.
  AUSTRALIA Macquarie Island 1997 i, iii 12,785ha Unique geological exposure of oceanic crust.
NEW ZEALAND New Zealand Sub-Antarctic Islands ii, iv 76,458ha + sea area High level of biodiversity and endemism among bird, plant and invertebrate populations.
  VIETNAM Ha Long Bay 1994 i, iii 150,000ha Karst islands with high scenic and landscape values; geological interest; biological diversity, especially in marine species.
BRAZIL Fernando de Noronha & Atoldas Roca 2001. ii, iii, iv




Largest concentration of seabirds in Western Atlantic, important for marine communities and marine landscape.


COSTA RICA Cocos Island National Park 1997, 2002 ii, iv 99,700ha Tropical rain forests on land, biodiverse marine areas.
Table 2.1: Island World Heritage Sites – some (Galapagos, Hawaii, Great Barrier Reef) are omitted as not relevant for comparison with St Kilda.


These sites are of similar character with comparable physical or biological interest to St Kilda. Table 2.2 below compares the distribution of natural heritage values across the six sites and St Kilda itself. This comparative analysis shows that St Kilda displays a wide range of natural heritage values of global significance when compared to existing similar sites on the World Heritage List. The only comparative sites are exclusively in the southern hemisphere, making St Kilda not only unique within the Palaearctic Realm but also in the northern hemisphere.

World Heritage Property
Natural heritage value
Globally important for seabirds
Significant ongoing coastal and marine geomorphological processes
Endemism & opportunities for research on isolated systems
Major rock cliff landform development
Exceptional submarine landscapes
St Kilda
Lord Howe Island
Gough Island
Heard & McDonald
New Zealand Sub-Antarctic Islands
Fernando de Noronha
Cocos Island

Table 2.2 Comparison of St Kilda with other island World Heritage Sites with similar natural values



In terms of seabirds alone St Kilda compares favourably with other, similar, World Heritage Sites. The largest concentration of tropical seabirds in the western Atlantic occurs on the Brazilian Atlantic Islands WHS. This assemblage comprises 150,000 breeding birds; St Kilda hosts about 700,000 breeding seabirds in an area less than half that of the Brazilian Atlantic Islands WHS. The New Zealand Sub-Antarctic Islands in the Southern Ocean hosts 40 species of breeding seabirds while St Kilda has 17 species in an area less than one-third of the size.

Isolated island systems provide an opportunity to conserve and study ecosystems that remain free from human interference. The state of conservation of the Island World Heritage properties listed here for comparison with St Kilda is uniformly high. St Kilda itself displays pristine marine and cliff environments with a high level of integrity. The proposed extension of the World Heritage Site boundary to include marine areas around the islands will further increase protection of the site and help to maintain a favourable conservation status. The importance of the marine areas around island World Heritage properties has been recognised by the IUCN and UNESCO in the context of World Heritage Sites. As an example, the recent (2002) extension of the boundary of the Cocos Island National Park (Costa Rica) was proposed to ensure adequate protection for the interlinked island and marine ecosystems. Such extensions can be expected to be implemented elsewhere.