Rangitoto Island - Biology

Biology

There are virtually no streams on the island so plants rely on rainfall for moisture. It has the largest forest of pōhutukawa trees in the world, as well as many northern rātā trees. In total, more than 200 species of trees and flowers thrive on the island, including several species of orchid, as well as more than 40 types of fern.

The island is considered especially significant because all stages from raw lava fields to scrub establishment and sparse forests are visible. As lava fields contain no soil of the typical kind, windblown matter and slow breaking-down processes of the native flora are still in the process of transforming the island into a more habitable area for most plants, which is one of the reasons why the local forests are relatively young and do not yet support a large bird population. However, the kākā, a New Zealand-endemic parrot, is thought to have lived on the island in pre-European times.

Goats were present on Rangitoto in large numbers in the mid 19th century, but were eradicated in the 1880s. Fallow deer were introduced to Motutapu in 1862 and spread to Rangitoto, but disappeared by the 1980s. The brush-tailed rock-wallaby was introduced to Motutapu in 1873, and was common on Rangitoto by 1912, and the brushtail possum was introduced in 1931 and again in 1946. Both were eradicated in a campaign from 1990 to 1996 using 1080 and cyanide poison and dogs.

Stoats, rabbits, mice, rats, cats and hedgehogs remained a problem on the island, but the Department of Conservation (DOC) aimed to eradicate them beginning with the poisoning of black rats, brown rats and mice and in August 2011, both Rangitoto and neighbouring Motutapu Islands were officially declared pest-free with both islands now also boasting populations of newly-translocated saddlebacks.

As the area is a DOC-administered reserve (in partnership with the 'tangata whenua' Ngāi Tai and Ngāti Paoa), visitors may not take dogs or other animals onto the islands.