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Ascension island

Last edited: Apr 5, 2022, 9:21 AM

About the territory

Ascension Island was first discovered in 1501 by a Portuguese seafarer, Joao da Nova Castella, but remained uninhabited until 1815 when a British naval garrison was located on the island whilst Napoleon Bonaparte was incarcerated on Saint Helena. In 1823 it was taken over by the Royal Marines and it remained under the supervision of the British Board of Admiralty until 1922 when it became a dependency of Saint Helena. From 1922 until 1964 the island was managed by the Eastern Telegraph Company (renamed Cable & Wireless in 1934). In 1964 an Administrator was appointed.

Map of Ascension Island

 

Located in the South Atlantic at latitude 7° 57’ South, longitude 14° 22’ West, Ascension Island is about 1125 km northwest of the island of Saint Helena. A volcanic island which is around one million years old it has a total land area of 88 km2. The climate is sub-tropical with temperatures ranging between 20°C and 32°C. Showers occur throughout the year with January-April being the wettest period. Annual rainfall is as much as 680mm on Green Mountain and as little as 130mm in the lowlands. There are a number of sea stacks and one small island, Boatswainbird Island, of about 5ha. The population of the Island is not permanent, and mainly made up of employees and families of the organisations working on the island. The last population census in 2016 was 806, comprising 556 St Helena citizens and 250 other nationalities. There are five settlements on the Island, including two military bases.

On 30 August 2019 the Ascension Island Marine Protected Area (MPA) was designated following a recommendation from the Island Council. The MPA covers 100% of Ascension’s Exclusive Economic Zone (EEZ), an area of over 440,000 square km, making it one of the largest MPAs in the world. Within the MPA, it is proposed that commercial fishing and mineral extraction will be prohibited, ensuring one of the highest levels of protection possible for this biodiversity hotspot.

The designation of the MPA was the culmination of many years’ of data gathering, planning and consultation to ensure that an informed decision could be made about the best approach to manage Ascension’s waters. This work was supported by the UK Government’s Blue Belt Programme, funding from Darwin Plus, EU BEST and the Great British Oceans Coalition as well as input from academic institutions and most importantly the elected Council and people of Ascension.

Biodiversity

The National Protected Areas Order 2014, created seven new protected areas so as to conserve Ascension’s wild and plant life, including the Island’s endemic species. The six new Nature Reserves and one new Sanctuary, in addition to Green Mountain National Park, mean that 20% of Ascension’s land is protected by measures for mitigating threats to vulnerable species.

The Kew online herbarium states that there are very few native plants on Ascension Island. There are probably 25 native vascular plants of which six ferns and six flowering plants are endemic. Most are threatened with extinction.

Ascension Island has 311 recorded species of land animals including a few that are now extinct. About 95 species are considered to be native including two marine turtles, 12 seabirds and two extinct landbirds. At least 138 species were probably introduced and 78 are of dubious status. There are about 29 endemic invertebrates including three genera of arthropods. There are no native species of terrestrial reptiles, amphibians or mammals except that the island is a major breeding site for green turtles (Chelonia midas).

There are four introduced species of reptile have been recorded with two known to be widespread (Gray’s Leaf-toed Gecko (Hemidactylus mercatorius) and Weigmann’s Swift (Liolaemus wiegmanni)). There is also a record of an African Clawed Frog but it is unclear if this species has become established.

There are eleven species of breeding seabirds including one endemic species, the Ascension Frigatebird (Fregata aquila). Most seabirds are now restricted to Boatswainbird Island or the inshore stacks rather than on the mainland. There are five resident landbirds, all introduced.

Policy and legislation

Ascension Island has an Environment Charter signed jointly with the UK Government. Guiding Principle 7 is to safeguard and restore native species, habitats and landscape features, and control or eradicate invasive species. Under the associated commitment 2 the government of Ascension Island will ensure the protection and restoration of key habitats, species and landscape features through legislation and appropriate management structures and mechanisms, including a protected area policy, and attempt the control and eradication of invasive species. Implementation progress was reviewed in 2007, 2010 and 2016, Read the 2016 review report (external link).

A South Atlantic Invasive Species Strategy and Action Plan agreed by the Governments of Ascension Island, Saint Helena, Tristan da Cunha, the Falkland Islands and South Georgia and the South Sandwich Islands was published in October 2010. This set out a number of strategic aims for the South Atlantic Overseas Territories in order to develop effective prevention and response measures for invasive species and thus reduce damage to their natural heritage, communities, livelihoods and options for future development. Key actions are grouped under five objectives: (A) Building awareness and support; (B) Co-ordination, co-operation and capacity-building; (C) Prevention; (D) Monitoring, early detection and rapid response; (E) Control, management and restoration.

In 2020 a biosecurity policy, and new biosecurity legislation was enacted in Ascension, with provisions for pre-border, border and post-border regulation of invasive species.

Invasive species and biosecurity

A total of 232 non-native species (marine and terrestrial) was recorded for Ascension by the RSPB Stocktake (Churchyard et al 2014).

Taxon

Total species

Non-native species

Invertebrates

595

113

Vertebrates

140

16

Plants

324

103

Problems with invasive non-native species

Introduced non-native species on the island have caused significant ecological problems. For example, non-native spiders, centipedes and ants have had an impact on the endemic invertebrate species, causing some extinctions. A number of introduced plants are regarded as invasive. For example the Mexican thorn tree (Prosopis juliflora) dominates large parts of the island and out-competes native plants, also leading to soil erosion. (Acacia farnesiana), Guava (Psidium guajava), Prickly pear (Opuntia vulgaris) and Bermuda cedar (Juniperus bermudiaana), all regarded as invasive , are well established in some areas and are likely to exclude any surviving native plant species as are various grass species (eg Greasy grass (Melinis minutiflora), Cow grass (Paspalum scrobiculatum), Cape grass (Sporobolus africanus)). Cottony cushion scale (Icerya purchasi) damages the endemic Ascension Island Spurge (Euphorbia origainoides).

Mynah birds (Acridotheres tristis) prey extensively on the eggs of native sooty terns Sterna fuscata. Other species such as cats (now eradicated) and rats prey on seabirds and newly emerging turtles. Feral donkeys, sheep and rabbits cause damage to native vegetation and can spread seeds of invasive species.

Invasive non-native Prosopis juliflora showing damage from introduced rats; non-native Acridotheres tristis; native Sterna fuscata.

L-R: Invasive non-native Prosopis juliflora showing damage from introduced rats; non-native Acridotheres tristis; native Sterna fuscata.

Priority invasive non-native species and actions

The main priorities for action have been to clear invasive plant species in order to allow the regeneration of some endemic plants. Following an island wide botanical survey in 2008 all known examples of Bullgrass (Juncos capillaceus) and Wild Mango (Schinus terebinthifolium) have now been removed. Other action has focused on the management of Mexican thorn which is widely established in the lowlands. Restoration of local vegetation has also involved excluding grazing animals such as rabbits.

Biosecurity

In 2017 a biosecurity gap analysis (PDF) was completed. Biosecurity capacity is generally low, and particularly weak for pre-border and border controls. A biosecurity review was carried out for Ascension Island in 2016, which included a detailed pathway analysis. Subsequently, a part-time biosecurity post was created and a number of actions initiated to strengthen biosecurity on the island, targeting identified risks. This includes border and post-border operations, and the development of a biosecurity policy. Risk analysis is not included, however, and no capacity to do this exists on the island.

In 2018 a pathway analysis (PDF) was completed. Pathways of introduction remain relatively few.
There is one harbour, and a military airport operated by the US Airforce. Passenger flights arrive from South Africa around once a month via St Helena Island, and more frequently from the US through the military airbase. Cargo comes mainly from the UK and South Africa via a monthly cargo ship from South Africa, also via St Helena.

Horizon scanning was carried out in 2019, identifying a total of 42 new invasive species of concern which have the potential to arrive within the next 5 – 10 years; read a report on the horizon scanning (PDF).  

Projects

A successful feral cat eradication project was initiated in 2001 with the last cat killed in January 2004. Indications are that some species of seabirds are recolonising the mainland now that the cats have been removed.

Drawing on commitments made under the Environment Charter, Overseas Territories Environment Programme (OTEP) funding was used in 2004-5 for a project to develop and initiate the implementation of Ascension’s first national park management plan (OTEP ASC 001). This included work to clear high priority endemic plant colonies of invasive vegetation and protect them from grazing. Eight OTEP funded projects (external link) were delivered in total between 2004 and 2012.


The South Atlantic Invasive Species project (SAIS) was undertaken during the period December 2006 to December 2009. It was funded by the Ninth European Development Fund and carried out by the RSPB in partnership with the Governments of Ascension Island, Saint Helena, Tristan da Cunha, the Falkland Island, South Georgia and the Sandwich Islands, Falklands Conservation and the Saint Helena National Trust. The overall goal of the SAIS project was to enhance the economic prosperity and quality of life of the people of the UK Overseas Territories (OTs) in the South Atlantic through the reduction of the threat that invasive species pose to the native biodiversity of the South Atlantic UKOTs, read more on the South Atlantic Invasive Species Project (external link). In 2010 a SAIS Strategy and Action Plan (external link) was developed, and in 2015 a regional workshop was held in 2015 in Ascension Island to implement key actions.

A two-year project (Defra CR 0492), was carried out by CABI in January 2011, looking at the impact of invasive non-native species in the UK Overseas Territories in the South Atlantic and the potential for biological control. Read more in the final report on the results for Ascension Island (external link).

A JNCC funded project was also carried out in 2012, for the ‘Management of endemic fern Marattia purpurascens’. The project covered erecting fencing to exclude rabbits and sheep from identified areas on Green Mountain, clearing of invasive species that threaten Ascensions endemic Marattia purpurascens, especially on the east-south-east side of the mountain, and the development and erection of educational pathway signage to raise awareness of the species and efforts underway to ensure its conservation.

Ascension Island has received a number of Darwin Initiative funded projects, listed below. For more information read the project reports (external link):

  • ‘Implementing a Darwin Initiative Biodiversity Action Plan (BAP) for Ascension Island’. This project developed and put into action a BAP for Ascension Island integrating available information on the spatial distribution of biodiversity, threats, and mitigation measures (Ref 19026).
  • ‘Taxonomic and conservation status of Oceanodroma storm petrels in the South Atlantic’ (DPLUS018).
  • ‘Ascension Island Marine Sustainability (AIMS) – a fisheries and marine biodiversity project’ (DPLUS021)
  • ‘Mapping Ascension Islands Terrestrial Ecosystem’ (DPLUS038)
  • ‘Tracking marine megafauna at Ascension Island: towards evidence-based ‘blue belts’’ (DPLUS046)
  • ‘Reduce, reuse, recycle — developing a waste management strategy for Ascension’ (DPLUS047)
  • ‘The Ascension Island Ocean Sanctuary (ASIOS) Project’ (DPLUS063)
  • ‘Improving biosecurity in the SAUKOTs through Pest Risk Assessments’ (DPLUS074)
  • ‘Building Ascension Island's Biosecurity Capability’ (DPLUS096)

The project ‘Tackling invasive non-native species in the UK Overseas Territories’ was implemented between 2016 and 2020 to strengthen biosecurity in the OTs, funded by the UK government Foreign and Commonwealth Office’s Conflict, Stability and Security Fund (CSSF). Ascension Island benefitted from a number of activities to strengthen its biosecurity, including: pathway analysis, horizon scanning, pathway action planning, legislative support for drafting biosecurity legislation, access to online learning, and technical support. Read further details.

The Blue Belt Programme seeks to enhance long-term sustainable marine protection strategies for the UKOTs, and provides £20 million of funding over 4 years (2016 to 2020), also funded by CSSF and delivered by the Centre for Environment, Fisheries and Aquaculture Science (Cefas). The Programme assisted the Ascension Island Government (AIG) and other partners in the designation of the Ascension Marine Protected Area (MPA) in 2019, through scientific research and advice on amendments to the existing Protected Areas Ordinance. Reports and further information can be found here.

Ascension was involved in the CSSF project ‘Natural Capital in the Caribbean and South Atlantic Overseas Territories’ from 2016 to 2019, and delivered to seven OTs by the Joint Nature Conservation Committee (JNCC). The programme of work involves mapping and valuing the participating OTs natural capital assets through integrating ecological data, satellite data, Geographic Information Systems (GIS) and economic assessments. Read project details and reports (external link). 

Useful information

Information for visitors

Before travelling please ensure all items are clean, free from organic materials such as mud, faeces, seeds and invertebrates:

  • Check your footwear, outdoor clothing and day packs to make sure they are clean and free from weed seeds, mud, invertebrates and plant material. If possible we recommend that you travel with new outdoor clothing and equipment. Shake out or vacuum all the compartments and pockets before you pack.
  • If you have been camping, check that your tent and other equipment is clean, dry and free of dirt and invertebrates such as ants and spiders. Shake it out before you pack it up for travel and ensure no soil remains on tent pegs.
  • If you have been hiking, visiting a wilderness area, farm or zoo, make sure your footwear and clothes are clean and free from seeds, mud and faeces. Check boot soles for mud between the treads, Velcro fastenings for seeds and plant material, and shake out or vacuum pockets to remove any dirt and plant material.
  • If you are carrying golf, fishing or other sports and outdoor equipment with you, make sure they are clean, dry and free from dirt and any live creatures.

Read more on biosecurity requirements for visitors and returning residents (external link).

Contact

Conservation Dept.
Ascension Island Government
Ascension Island
South Atlantic Ocean
ASCN 1ZZ

Tel: +247 66403

Documents

Barnsley, S., Cary, E., Pienkowski, M. and Wensink, C.(Eds) (2016).  Review of performance by 2016 of UK Overseas Territories and Crown Dependencies in implementing the 2001 Environment Charters or their equivalents and moving towards the Aichi Targets and Sustainable Development Targets. UK Overseas Territories Conservation Forum, April 2016.

Churchyard, T., Eaton, M., Hall, J., Millett, J., Farr, A., Cuthbert, R. and Stringer, C.  (2014). The UK’s wildlife overseas: a stocktake of nature in our Overseas Territories.  Sandy, UK: RSPB.

Edgar, P. (2010). The Amphibians and reptiles of the UK Overseas Territories, Crown Dependencies and Sovereign Base Areas: Species Inventory and Overview of Conservation and Research Priorities. Bournemouth, UK: Amphibian and Reptile Conservation.

Proctor, D. and Fleming, L. V., eds. (1999). Biodiversity: the UK Overseas Territories. Peterborough, UK: JNCC.

Sanders, S. M., ed. (2006). Important Bird Areas in the United Kingdom Overseas Territories. Sandy, UK: RSPB.

Varnham, K. (2006). Non-native species in UK Overseas Territories: a review. Peterborough, UK: JNCC Report No. 372.

Websites