From farm to forest – 50 years of ecological transformation on Mana Island, New Zealand

Abstract

Ecological surveys of Mana Island, Wellington, in 1972 and 1975 confirmed that house mice (Mus musculus) were the only pest mammals present, and resulted in nationally significant populations of Cook Strait giant weta (Deinacrida rugosa) and of two threatened lizard species being confirmed or discovered. Photographs taken in June 1972 were re-taken in June 2022, and are used to document social and ecological change on the island over this 50-year interval. Mana Island was farmed until 1986, and has been a conservation reserve administered by the Department of Conservation (DOC) since 1987. Mice reached plague numbers after farm stock were removed, and caused a population crash of McGregor’s skink (Oligosoma macgregori). Following mouse eradication in 1989–90, the island has been free of introduced mammals. A major revegetation effort since 1987 included planting of more than 443,000 trees and shrubs over about 36% of the 217 ha island. For the last two decades, conservation management of the island has largely followed a comprehensive ecological restoration plan that was published in 1999. The Friends of Mana Island was formed in 1998, and has taken the lead role in most conservation initiatives on the island since then, in partnership with Ngāti Toa Rangatira (mana whenua) and DOC. In addition to the revegetation programme, weed control, and recreation of a wetland, 22 animal species have been translocated to the island, and several bird species have colonised naturally. Conservation successes and failures are described, and research relevant to restoration ecology undertaken on the island is summarised.