Gough and Inaccessible Islands

Invasive/alien terrestrial species (mice) (issue mentioned since 1999)

N/A

On 30 November 2022, the State Party submitted a state of conservation report for the property, which is available at https://whc.unesco.org/en/list/740/documents/, and provides the following updates:

• In 2021, the house mouse (Mus musculus) eradication programme was implemented following COVID-19-related delays. Funded by the State Party and various donors, the programme was undertaken by a partnership led by the Royal Society for the Protection of Birds (RSPB) and the Government of Tristan da Cunha, alongside the governments of the United Kingdom and South Africa, and three non-governmental organizations;
• The eradication programme significantly reduced the population of house mice on the island on a temporary basis, with a near absence during the 2021 breeding season. This resulted in a substantial improvement in breeding success (up to a doubling) for a variety of seabirds important to the property’s Outstanding Universal Value (OUV);
• However, despite following international guidelines and best practices for eradicating invasive alien species, the project was declared unsuccessful with mice recorded on Gough Island after its completion and the population rapidly increasing thereafter. House mice are likely to significantly reduce the breeding success of seabirds on Gough Island in the future. The State Party remains committed to support the eradication efforts of the RSPB and partners;
• An independent review has been initiated to identify all the factors that contributed to the failure of the eradication programme and is expected to conclude by mid-2023;
• Captive populations of Gough moorhens (Gallinula comeri) and Gough buntings (Rowetta goughensis) were temporarily held as a precautionary measure to prevent collateral impact on non-target species during the bait application;
• Experts have concluded that the eradication of the procumbent pearlwort (Sagina procumbens) is no longer possible, but containment and biosecurity measures are being implemented to prevent its further spread on the island;
• Due to practical challenges of biological surveying, it is not possible to obtain information on detailed population dynamics for all species that are part of the property’s OUV; however, the project has contributed to a temporary improvement in the breeding success of five seabird species;
• No immediate risk has been identified as a result of the fishing vessel which sank near Gough Island in October 2020, however confirmation from authorities in Tristan da Cunha is still outstanding;
• Highly Pathogenic Avian Influenza (HPAI), which affects many seabird populations in the northern hemisphere, has not been recorded on Gough Island. It is being closely monitored by the authorities as it may occur in the future.

The extensive preparation and implementation of the complex 2021 house mouse eradication programme on Gough Island should be appreciated, despite the disappointing outcome. The resulting immediate improvement in reproductive success of five flagship seabird species, albeit temporary, demonstrates the utmost importance and urgency of finding a permanent solution to house mice eradication on Gough Island. The initiation of an independent review of the eradication programme is noted and its findings should be critically examined to feed into the development of a new phase of the programme. The State Party should also be strongly encouraged to use the findings of the independent review to record and disseminate lessons learnt to continue promoting knowledge exchange with other States Parties who may also be planning eradication programmes. In this regard, the continued commitment of the State Party to sustain its support to RSPB and other partners to eradicate the house mouse from the island is welcomed and considered vital to the future of the property.

It is noted with concern that experts have now determined that the eradication of the invasive plant species procumbent pearlwort (Sagina procumbens) is no longer possible. In the context of the containment operation, which the State Party reports is now being implemented, further information is required on the current spread of the plant, and efforts need to be focused on preventing further spread in the interior of the island and other highly sensitive locations. These preventative measures to curb the spread of the plant, together with the continued implementation of strict biosecurity measures on the island, will need to be sustained in the long term. It is recommended that the Committee request the State Party to conduct an analysis of the impacts of the procumbent pearlwort on endemic species of plants and associated invertebrates, and to develop a long-term containment plan. Changes in habitat structure could also lead to losses of suitable nesting habitat for seabirds that are part of the OUV of the property.

The challenges of establishing detailed population dynamics of the species that are part of the property’s OUV are noted. However, the lack of such data makes it difficult to monitor the state of conservation of a property, which was inscribed on the World Heritage List for hosting some of the world’s most important seabird colonies. It is thus recommended that the State Party be encouraged to establish monitoring that would provide information on the current status of the OUV of the property.

Whilst acknowledging that no immediate risks have been identified as a result of the fishing vessel which sank near Gough Island in October 2020, the State Party should be encouraged to continue monitoring the situation for potential impacts.

It is positive that no cases of HPAI have been recorded in the property, considering the importance of migratory seabirds to the OUV. Recalling the significant impact of HPAI in other regions, it is recommended that the State Party continue to monitor the situation closely.