The Ground Baiting Component of the Gough Island House Mouse Eradication Attempt in 2021

Authors

• Araceli Samaniego, Manaaki Whenua – Landcare ResearchFollow
• Andrew Callender, Royal Society for the Protection of Birds
• Pete McClelland

Date of this Version

Fall 2023

Document Type

Article

Citation

Human–Wildlife Interactions (Fall 2023) 17(2): article 5 

doi: 10.26077/jg7t-4j11 

Special topic: Island invaders 

Comments

Open access. License: CC BY 4.0

Abstract

House mice (Mus musculus; mice) are among the most widespread invasive species. On Gough Island (6,500 ha), mice preying on at least 19 bird species triggered a mouse eradication attempt. Gough Island is a volcanic island in the South Atlantic Ocean and part of Tristan da Cunha, a UK Overseas Territory. From June to August 2021, an expert team applied an anticoagulant rodenticide (active ingredient brodifacoum at a concentration 20 ppm) island-wide, predominantly via aerial broadcast using helicopters, as the island is mainly uninhabited. However, hand-baiting was also required because of the presence of a staffed meteorological station. The bait was hand broadcasted in and around buildings immediately after each of the 3 aerial applications in that area. Outdoor ground baiting covered the aerial exclusion zone (e.g., aviculture area, outside of buildings and surrounding shrubs; ~2 ha) using 8–10 kg ha^–1 per application (i.e., matching aerial baiting rates), with kill-trapping for monitoring purposes occurring just prior to baiting (n = 123 traps). Baiting of buildings required bait to be placed under and inside all buildings, with 5 bait pellets placed in open trays (i.e., plastic petri dishes), and with at least 1 tray/room. Trays under buildings (n = 117) were set and baited the day after baiting first occurred outdoors. The following day, trays inside buildings (n = 135) were set and baited. Fresh bait was available under and inside buildings for 5 and 7 weeks, respectively. Trapping success was high (57%) the day before baiting began (June 12), and zero the following week and until baiting termination on August 12. Mice reappeared 6 months after the baiting operation began. However, this ground baiting approach may be useful for a future mouse eradication attempt at Gough Island or for similar projects.