THE ACAP MONTHLY MISSIVE. What is the “state of play” with planned predator eradications on two sub-Antarctic islands?

 The sheer western cliffs of Auckland Island, photograph by Finlay Cox

Eradicating invasive pests on seabird-breeding islands has been undertaken for over 50 years and has become established as one of the most immediate ways of helping restore island ecosystems.  During that time invasive mammals have been eradicated from over 700 islands globally.  A body of knowledge and experience that has been built up has resulted in a high success rate, while generating a well-defined set of practical principles that maximise the likelihood of success of each eradication that follows.  Rat species are prevalent on islands worldwide and have thus been a common target for eradication, but in the past two decades jujhHouse Mice have increasingly been targeted, with mouse eradications also having a high success rate.  Where projects have been unsuccessful, their managers and scientists then engage in reviews to identify and integrate key lessons into future operational planning.

The record following eradication projects for the sub-Antarctic islands around the Southern Ocean overall is also a good one.  Australia’s Macquarie Island is free of its cats, rabbits, rats and mice, New Zealand’s Campbell Island of its sheep, cats and rats, and more recently New Zealand’s Antipodes Island of its mice.  Over in the South Atlantic South Georgia/Islas Georgias del Sur* is now free of Reindeer, rats and mice.  France’s Amsterdam Island has recently been the subject of an eradication project to rid it of feral cats, rats and mice, and so far the results seem promising; it earlier had its feral cattle removed.  However, not every eradication project in the sub-Antarctic has been successful: mice remain on France’s St Paul (although its rats were eliminated) and mice have survived the eradication effort on the United Kingdom’s Gough Island in 2021.  And there still remain some important seabird islands in the Southern Ocean with introduced mammals awaiting eradication attempts (although on some of them research on their pests has been undertaken).  These include France’s Crozet Islands and Kerguelen (multiple species), and Steeple Jason (House Mice) in the Falkland Islands/Islas Malvinas*.

Some islands in the Southern Ocean have fortunately have remained free or largely free of invasive mammals.  These include the UK’s Inaccessible (feral pigs died out) and Nightingale (both part of the Tristan da Cunha group), South Africa’s Prince Edward Island, Australia’s Heard and McDonald Islands, and New Zealand’s Bounty and Snares Islands.

Fatally attacked by Marion Island’s introduced House Mice, this Wandering Albatross chick soon died of its injuries, photograph by Vanessa Stephen, 06 July 2024

For this month’s Missive I reached out to managers and scientists involved with intended eradication efforts on two sub-Antarctic islands, Auckland and New, to ascertain the “state of play”.  I do not consider here South Africa’s Marion Island where House Mice are seriously ravaging its albatrosses and petrels, primarily because progress by the Mouse-Free Marion Project with its active website news section and social media postings continues to be regularly featured by ACAP Latest News.

Auckland Island

White-Capped Albatross or Toroa Thalassarche steadi on Auckland Island, photograph by Jake Osbourne

The information below comes from Veronika Frank and Stephen Horn, National Eradication Manager, New Zealand Department of Conservation.

A technical feasibility study for the eradication of pigs, feral cats and mice (feral goats had been previously removed) from the main 46 000-ha Auckland Island in the New Zealand sub-Antarctic was undertaken between 2017 and 2021 leading to a detailed report.  Research findings from the study were published in a number of individual papers in a special issue of the New Zealand Journal of Ecology the following year.

Following a pause in progress due to the COVID-19 epidemic, eradication of the three mammalian invaders is now another step closer thanks to recent Government funding of NZD 3.65 million over two years.  These funds will enable foundational work to ready the eradication project for initiation.  Progress on research and development objectives include:

• development of a meat cat bait for use in New Zealand: two successful hand-laid trials completed and an aerial trial currently underway to support registration of this bait;
• development of efficient cat-trapping techniques and detectability with camera networks;
• successful testing of a feral pig bait and in-field GPS-tagging techniques; and
• development of an effective image classifier using artificial intelligence for managing trail cameras.

A feral cat feeds on the body of a White-capped Albatross chick close to fledging, Auckland Island, photograph by Stephen Bradley

The objectives of the current “Readiness Phase” include:

1. securing the remaining funding required to initiate the eradication project (NZD 78 million total over eight years) through donations, partnerships and Government investment.
2. establishment of project management, governance, and project delivery structure(s) and recruitment of core team members to progress planning and produce a suite of planning documents such as a Project Plan and Procurement Strategy
3. Complete research and development for required tools, which include:

• registration of the new feral cat bait;
• improved helicopter bucket for reliable distribution of rodent bait at low sow rates; and
• remotely reporting camera setup and communications system using artificial intelligence with high accuracy to report on target species detections as they occur.

A “storymap” with the title “Preventing extinctions and saving entire ecosystems Subantarctic Auckland Island, New Zealand” dated March 2024 sets out in visual terms the project.

New Island

Landsend Bluff on New Island, photograph by Ian Strange

Information below comes from Ross James of the NGO Falklands Conservation.

The New Island National Nature Reserve is considered one of the most globally significant wildlife sites in the Falkland Islands (Islas Malvinas)* and is in major need of restoration.  Four invasive mammal species, feral cats, European Rabbits, Black Rats and House Mice, threaten the site’s fauna and are degrading the island’s fragile habitats. Their removal is required for recovery and long-term climate resilience.  The New Island Restoration project aims to complete the preparatory technical steps necessary for an ambitious four-species eradication programme and engage the Falkland Islands Government and community to secure support for New Island’s long-term restoration.

Video by Falkland Conservation

“The feasibility report is currently in the process of being externally reviewed and so isn't ready to make public yet, but as with the 2013 report by Derek Brown the findings were that the removal of all four invasive mammal species remains feasible.  Phase 1, which concluded in March enabled us to collate all the technical data required, develop mitigation strategies, identify partners and secure permissions, and we're currently in the fundraising stage to enable Phase 2 (the actual restoration work) to begin.  We've recently updated the website to reflect this transition, which includes a stronger message - not if we should do it, but that we are fundraising in order to do it.  We're in a better position than ever before to deliver the restoration of NI, and the island needs it now more than ever.”

Read more under the heading “New Island: completing preparatory steps for restoration against invasive mammals” and download progress reports on the Darwin Plus grants scheme website here.

 
A Black-browed Albatross Thalassarche melanophris pair on New Island, photograph by Ian Strange

References:

Brown, D. 2013.  New Island Feasibility Study Report for the Potential Eradication of Ship Rats, Mice, Rabbits and Feral Cats from New Island, Falkland Islands.  Unpublished report for New Island Conservation Trust.  87 pp.

Department of Conservation 2021.  Technical Feasibility Study Report for Eradication of Pigs, Mice and Cats from Auckland Island.  Invercargill: Department of Conservation Te Papa Atawhai.  123 pp.

Russell, J.C., Horn, S.R. & Broome, K.G. (Eds) 2022.  Restoration of New Zealand subantarctic islands.  New Zealand Journal of Ecology 46(3).

With thanks to Veronika Frank, Stephen Horn, Ross James, Mark Tasker and Megan Tierney for information.

John Cooper, Emeritus Information Officer, Agreement on the Conservation of Albatrosses and Petrels, 11 October 2024

*A dispute exists between the Governments of Argentina and the United Kingdom of Great Britain and Northern Ireland concerning sovereignty over the Falkland Islands (Islas Malvinas), South Georgia and the South Sandwich Islands (Islas Georgias del Sur y Islas.