Size & Significance

Nationally pest-free islands make up 0.4% of NZ’s land area yet are essential for protecting over 50% of NZ’s threatened birds and over 30% of NZ’s threatened reptiles. At 1,872 ha Ahuahu is in the top ten largest pest free islands in NZ. Ahuahu is five times larger than all the other Mercury Islands put together, and almost three times the size of every other pest-free island on the Coromandel combined. The scale of Ahuahu also brings a greater diversity of ecosystems, including permanent water. Ahuahu has great potential to have functioning ecosystems and hold sustainable populations of threatened species. Currently the island is approximately 1/3 sheep and beef farm, 1/3 pine forest (which won’t be logged) and the remaining 1/3 in various types/states of native habitat. Many native species are utilising the pastures and pine forest.

Public Access

The owners have allowed public access to the island for day visitors since the late 1970’s. Ahuahu is a focal point for boating from Mercury Bay and between Tauranga and Auckland.

Species Found on Ahuahu

From translocations, surveys and observations some of the notable species on Ahuahu include tīeke, Mercury Islands tusked wētā, moko skink, shore skink, pacific gecko, common gecko, pāteke, grey-faced petrel, fluttering shearwater, NZ dotterel, kākā, kererū, white-fronted tern, red crowned kākāriki, white-faced storm petrel, Pycroft’s petrel, Caspian tern, bittern, parapara (bird catching tree), milk tree, māwhai, pīngao, katipō, ground wetā and 51 species of native land snail, indicating extremely high levels of biodiversity.

The Mercury Islands Archipelago

The Mercury Islands lie 6-10 kilometers North to Northeast off the Coromandel Peninsula. Six islands, except Ahuahu, are managed by DOC as highly valuable reserves, with access restrictions in place, for the purpose of protecting and preserving in perpetuity indigenous flora and fauna or natural features. The islands are internationally significant, listed as important bird areas primarily for the seabird values, and are included in tentative lists for UNESCO World Heritage status. The criteria for this inclusion is to contain the most important and significant natural habitats for in-situ conservation, containing threatened species of outstanding universal value for science or conservation. The Mercury Islands has an incredibly rich seabird and reptile fauna as well as being home to the Mercury Island tusked wetā and a suite of species dependent on conservation for their survival. Until 11,000 years ago, a land connection existed between the Mercury islands and the Coromandel Peninsula. Thus, the islands are regarded as continental shelf islands. By 6,000 years ago sea level had risen approximately to its current position, marooning species. Middle and Green Islands which have never had introduced mammalian pests support extraordinary densities of seabirds, reptiles and invertebrates, are benchmarks for island conservation.

The Mercury Islands are part of the Hauraki Gulf Marine Park. The intent of the Hauraki Gulf Marine Park is to integrate the management of the natural, historic, and physical resources of the Hauraki Gulf, its islands, and catchments: recognising the historic, traditional, cultural, and spiritual relationship of the tangata whenua with the Hauraki Gulf and its islands. Whilst Ahuahu’s land is not included in the Park the intent to protect the natural, historic, cultural and spiritual values is recognised. DOC, Regional Councils and District Councils are obligated to give regard to the intent of the Hauraki Gulf Marine Park.

Information on this page has been written and supplied by Pete Corson.

Background photo by Jamie Reyneke-Barnard