West Coast (44715)
St Helena (to UK), Africa
Site overview
KBA status: confirmed
Global KBA criteria: D1a
Year of last assessment: 2015
National site name: West Coast
Central coordinates: Latitude: -16.0055, Longitude: -5.7605
System: marine, terrestrial
Elevation (m): 0 to 490
Area of KBA (km2): 6.49574
Protected area coverage (%): 30.89
KBA classification: Global
Legacy site: Yes
Site details
Site description: The site comprises the South West coast of St Helena extending along the south coast to Lot’s Wifes’ Ponds and along the west coast. The coast is dominated by imposing arid basltic sea cliffs, rising mainly to between 300 m and 570 m. The site includes the offshore islands of Egg Island (79 m2), Speery Island (120 m2) and other islets and stacks including Castle Rock, Asses Ears and Gorillas head. Encircled by breakers, with landing difficult, both islets are barren, with heavy guano deposits at upper levels. The site includes one vegetation zone consisting of incised semi-desert habitat with large-scale erosion, dominated by Suaeda, Lantana and Carpobrotus which borders onto the Southern Pastures.
Rationale for qualifying as KBA: This site qualifies as a Key Biodiversity Area of international significance that meets the thresholds for at least one criterion described in the Global Standard for the Identification of KBAs.
Additional biodiversity: See table for key species. There are 10 breeding species of seabirds in St Helena: Bulweria bulwerii, Pelagodroma marina, Oceanodroma castro, Phaethon aethereus, Sula dactylatra, Sula leucogaster, Onychoprion fuscatus, Anous stolidus, Anous minutes and Gygis alba (Prater, 2012). Egg Island on the West coast supports significant populations of band-rumped storm-petrel Hydrobates castro with two distinct seasonal populations with 7145 individuals in the hot season and 4512 individuals in the cool season (Beard et al, 2014). These populations represent the most southerly breeding colony in the Atlantic of this species. H.castro has a global distribution but recently in the Azores the seasonal populations were found to be separate species (Bolton et al., 2008). A recent study has shown phonological and acoustical differences between the seasonal populations (Beard et al., 2014). If confirmed through genetic studies, one of the seasonal populations may represent an endemic globally-restricted species (Beard et al., 2014). The offshore islands support the part of the most southerly breeding colonies of red-billed tropicbird in the Atlantic, with 79 individual present on the West coast colony (George & Beard, 2014). Masked booby Sula dactylatra were first recorded breeding in the mid 1980s (Rowlands et al., 1998) and c.200 adults were seen around George and Shore Islands in the 1990s with a limited number of breeding pairs. From 2009 a number have bred on the top ridges on the mainland near Lot’s Wife’s Ponds and by 2011 over 150 adults were present with 40 pairs breeding successfully (Bolton et al., 2011; EMD data). A Bulwer’s petrel Bulweria bulwerii was found to potentially be breeding on Egg Island in 2011 (Oppel et al., 2011). There is one confirmed record of a white-faced storm-petrel which is likely to have fledged from Egg Island (Bolton et al., 2009). Non-bird biodiversity: The seas around St Helena support a small number of Whale Sharks Rhincodon typus from January to May along with resident Pantropical Soptted Dolphins Stenella attenuata and a few bottlenose dolphins Tursiops truncatus (Prater, 2012). Humpback Whales Megaptera novaeangliae calve off the coast from June to December. The waters are regularly used by Hawksbill Eretmochelys imbricata and Green turtles Chelonia mydas (Prater, 2012).
Delineation rationale: South-west St Helena (SitRecID 6825) has been split into two IBAs: West Coast (SitRecID 44715) and Gumwood Hill (SitRecID 44716) (UKOTs Review 2015 - Sarah Havery / Jonathan Hall [RSPB] pers. comm.).
Habitats
Land use: fisheries/aquaculture | military | nature conservation and research | not utilised | urban/industrial/transport
Threats
Summary of threats to biodiversity at KBA: From the excavation and analysis of bone deposits it is clear that a substantial number of seabirds were breeding on the island prior to the introduction of non-native species (Olson, 1975; Lewis, 2008) including three presumed endemic species that are now extinct including a Pterodroma (rupinarum), Bulweria (bifax) and Puffinus (pacificoides) and four extant but extirpated species including Puffinus lherminieri, Fregata minor, Fregata ariel and Pelagodroma marina. Now only the offshore islands, stacks and steep cliffs provide predator-free breeding areas. Predation by invasive species is likely to be restricting Hydrobates castro to the offshore Egg Island as there has been some evidence of attempted breeding on the mainland (Prater, 2012). The site is mostly covered by the Sandy Bay National Park and informal consultation with stakeholders has occurred for this area leading to the production of a draft management plan which will soon be publicly available (Higgins, 2014). All of the offshore islands, islets and stacks are designated Nature Reserves.
Additional information
References: Beard et al. (2014), Bolton et al. (2011), Bolton et al. (2009), Bolton et al. (2008), George & Beard (2014), Higgins (2014), Lewis (2008), Olson (1975), Oppel et al. (2011), Prater (2012), Rowlands et al. (1998).