Great Barrier Island Environmental News

Beyond the Barrier
Environmental news from NZ and around the world

Million Dollar Mouse’ - eradicating mice from the Antipodes Islands

The Million Dollar Mouse pest eradication project on the Antipodes Island in the sub-Antarctic was completed in mid-July. The islands lie 760km east of Dunedin.

Touted as the most challenging pest eradication ever carried out in New Zealand, the project was described by Conservation Minister Maggie Barry as a “globally significant conservation achievement, safeguarding a unique, remote and forbidding land and the many extraordinary species living there.”

Photo: K. Springer

The islands are home to endemic species such as the Reischek’s and Antipodes Island parakeets, snipe and pipit, thousands of seabirds and marine mammals.

Three helicopters were used to drop 65 tonnes of bait to the island. Total eradication of mice cannot be confirmed until a monitoring team visit the island in 2018.

Find more information about Million Dollar Mouse at:

Gains from Mammal Eradications

A recent paper by Jones et .al.,1 reviewed available literature and databases and used expert interviews to estimate the global conservation benefits of invasive mammal eradications on islands. The research quantifies the benefits to native island fauna of removing invasive mammals. Islands house disproportionately high biodiversity compared with mainlands; they occupy 5.5% of the terrestrial surface area but contain more than 15% of terrestrial species, 61% of all recently extinct species, and 37% of all critically endangered species on the International Union of the Conservation of Nature (IUCN) Red List.

Jones et .al., found 236 native terrestrial faunal species that had benefitted from 251 eradications of invasive mammals on 181 islands. Seven native species were negatively impacted by mammal eradication. Four threatened species had their IUCN Red List extinction-risk categories reduced as a direct result of invasive mammal eradication, and no species moved to a higher risk category.

The authors predict that 107 highly threatened birds, mammals, and reptiles on the IUCN Red List likely have benefitted from mammal eradications on islands. Overall, Jones et .al., conclude that their results highlight the importance of invasive mammal eradication on islands for protecting the world’s most threatened fauna.

Beach Models Saving Seabirds

Plaster of Paris seabird models are being used to encourage Little Terns to nest. These seabirds that are found throughout Europe and in parts of Africa, India, New Zealand. Little Terns are migratory, and travel to favourable nesting sites for breeding. Busy beaches have become less welcoming to the birds, and their numbers have been steadily declining.

The models, placed on beaches where the terns like to nest have successfully encouraged nesting.

1Jones et. al., 2016. Invasive mammal eradication on islands results in substantial conservation gains. PNAS, April 12 2016, vol 113, no.15 pp 4033-4038.


Great Mercury predator/pest free

The Great Mercury Island (Ahuahu) has been added to the list of pest and predator free islands of the Hauraki Gulf. Minister of Conservation Maggie Barry made the announcement on Great Mercury in May.

The islands are owned by David Richwhite and Sir Michael Fay.

After the rat eradication in 2014, two years of surveillance and regular pest-hunting dog patrols have found no rodents remaining on the 1872 hectare island.

Predator and pest free islands of the Hauraki Gulf (shaded in green)
Great Mercury Islands are at bottom right.  Image: Google Earth, 2016.

The eastern Coromandel islands are home to a tusked weta found nowhere else in the world, kaka, saddleback, little spotted kiwi, tuatara, ten different species of lizards and hundreds of thousands of seabirds.

The representative from Ngati Hei, Joe Davis said at the ceremony that having the group of islands pest free will have a positive effect on the whole of Hauraki. 

"For Hauraki, every island that they can restore is a move in the right direction. It gives our flora and fauna a way better chance of survival on these islands."

"We're starting to deal with the social and cultural aspects of the restoration," he said. 

"We're learning how people relate with the environment and we're telling people about the dangers of the pests being on the islands.”

(Sources: Department of Conservation,

Environmental News Issue 36 Winter 2016