Cover illustrations: Mainland Antigua from Maiden Island West. Credit Sophia Steele – Fauna & Flora International THE OPINIONS OF THE AUTHORS DO NOT NECESSARILY REFLECT THE OPINIONS OF THE PARTNER ORGANISATIONS OF THE OFFSHORE ISLANDS CONSERVATION PROGRAMME. PUBLISHED BY Offshore Islands Conservation Programme St. John’s, Antigua RECOMMENDED CITATION Lawrence, S.N., Bell, E.A., Challenger, S.C. & Steele, Sophia (2019) Technical Report for the Eradication of Black Rats Rattus rattus from Maiden Island West, Antigua. Report for the Offshore Islands Conservation Programme, St John’s, Antigua and Barbuda. The award-winning Offshore Islands Conservation Programme (OICP) was established in 1995 as the Antiguan Racer Conservation Project, and operates under a partnership between the Government of Antigua and Barbuda, Environmental Awareness Group, Durrell Wildlife Conservation Trust and Fauna & Flora International. This partnership is working towards the Vision of healthy, functioning coastal ecosystems that are sustainably managed for the conservation of native wildlife and for the benefit of local people. Our activities include environmental education, endangered species management, invasive species control, habitat restoration, research and monitoring, and strengthening local governance and management capacity. This study was co-funded by the U.S. Fish & Wildlife Service under the Neotropical Migratory Bird Conservation Act Program, Project #F17AP00667 - Improving and Conserving Critical Bird Habitat on Antigua & Barbuda’s Offshore Islands, and the Global Environment Facility Grant - Preventing the COSTS of IAS in Barbados and the OECS. Contact details: Ms Natalya Lawrence, Project Coordinator, Offshore Islands Conservation Programme, Environmental Awareness Group, P. O. Box 2103, St John’s, Antigua, West Indies. www.eagantigua.org; Email: [email protected] ii 1. Executive Summary Since 1995, the Offshore Islands Conservation Programme (OICP) has eradicated harmful alien invasive mammals from 15 offshore islands around Antigua. This has resulted in visible improvements in habitat quality and significantly boosted the populations of rare and endemic reptiles, birds, invertebrates and plants (Daltry et al., 2014). This is the Technical Report following the operation to eradicate black rats Rattus rattus from Maiden Island West (1.21 hectares) in accordance with the methods recommended in the Operational Plan and Feasibility Study Report produced for the island. Maiden Island West is a part of the globally recognised Important Bird & Biodiversity Area (IBA – AG006) and Offshore Islands Key Biodiversity Area, and lies 0.72 km off the southwestern coast of Antigua. The operation was administered by partner organisations of the OICP, particularly by the Environmental Awareness Group and the OICP Coordinator Natalya Lawrence during the fieldwork stage of the operation. The eradication was facilitated by Elizabeth Bell but was completed under the leadership of Natalya Lawrence. The eradication was completed with a steady team of local and regional volunteers from the Boys’ Brigade of Antigua and Barbuda, volunteers and interns from the Department of Environment, volunteers from the Community Development Division and from the Environmental Awareness Group. The owners of Maiden Island West, the Hall Family, were also crucial to the success of the eradication, providing transportation, shelter, and facilities for the eradication team as well as participating in the execution of the eradication. Equipment and all necessary approvals were in place by 27th June, and the field work began on 30th June, 2018. The eradication operation was officially completed by 17th August, 2018. At the end of the operation, all equipment and material were removed from the island leaving 13 lockable permanent bait stations in place, with a maximum separation of 30m between stations. During the eradication operations, several stations were consistently attacked by hermit crabs. The bait poses no threat to the crabs. Although there was concern that the crabs would get to the bait and consume it all before the rats could, trail cameras showed that the rats were easily able to access and help themselves to the bait. Other non-target species, including ants, cockroaches and mould, had much less impact on bait take. There was no evidence of non-target species being affected by the bait or subjected to secondary poisoning throughout the operation. One dead juvenile black-crowned night heron was collected and a necropsy was done. Results showed no signs of secondary poisoning. After consultation with Elizabeth Bell, it was determined that the bird could have died from natural causes. The intensive monitoring phase of the operation suggested that all rats had been eradicated from Maiden Island West. The long-term monitoring will be undertaken by the Hall Family on a monthly basis. 3 There were several sightings of mongooses on the mainland (Seaforth area) close to the island. However, no mongooses have ever been detected on the island (either historically or presently) and the distance needed to be swum by a mongoose to reach the island would be very unattractive to these animals. Nevertheless, it would be wise to have a biosecurity protocol for mongooses in place in the event that they are inadvertently transported to the island. In summary: 1. The eradication of black rats from Maiden Island West was a ground-based operation using bait stations and Klerat brodifacoum grain-based wax blocks that was completed by August, 2018. 2. The eradication of rats from Maiden Island appears to be successful. 3. In line with common international practice, Maiden Island West can only be officially declared rat- free if no further signs are detected within 2 years of eradication. 4. Bait station interference from hermit crabs was high. 5. There was no evidence that non-target species were affected or subjected to secondary poisoning throughout the operation. 6. Ecological monitoring of seabirds, land birds, reptiles and vegetation should be initiated and continued to document the effects of the eradications on the native flora and fauna. 7. Only with constant vigilance and an ongoing commitment from all OICP staff and the Hall Family to prevent, detect and respond to any incursions will the overall goal of the operation be achieved. 4 2. Table of Contents 1. Executive Summary ....................................................................................................................... 3 2. Table of Contents .......................................................................................................................... 5 3. Acknowledgements ....................................................................................................................... 6 4. Introduction ................................................................................................................................... 7 4.1 Purpose and Scope of the Technical Report .................................................................. 7 4.2 Implementing Agency and Sponsors .............................................................................. 7 4.3 Context for Maiden Island West’s Restoration .............................................................. 7 5. The Reasons for the Maiden Island West Rat Eradication ............................................................ 8 6. Project Site and Target Species ..................................................................................................... 9 9 6.1 Maiden Island West ....................................................................................................... 9 6.2 Black Rats ..................................................................................................................... 10 7. Eradication Preparation, Implementation and Monitoring .......................................................... 12 7.1 Summary of Activities for Phase 1 of the Eradication .................................................. 12 7.2 Summary of Phase 2 of Maiden Island West Eradication ............................................ 17 8. Crab Interference ......................................................................................................................... 21 9. Problems Encountered ................................................................................................................. 22 10. Recommendations ....................................................................................................................... 22 11. Conclusions ................................................................................................................................. 22 12. References ................................................................................................................................... 24 13. Appendix ..................................................................................................................................... 26 13.1 Eradication Schedule ........................................................................................................... 26 13.2 Biosecurity Checklist for Hall Family ................................................................................. 30 13.3 Bird Species Observed......................................................................................................... 33 5 3. Acknowledgements This work was supported by the Offshore Islands Conservation Programme (OICP) with financial