An island in New Zealand’s Bay of Plenty has made a remarkable ecological recovery after years of damage caused by introduced animals. Moutohora, also known as Whale Island, was once described as bare soil and rock in its most degraded state. Goats, rabbits, sheep, cats and Norway rats had altered its landscape and affected native wildlife. More than 11,000 plants from 45 species were established during a major planting programme. The island was then managed with a focus on protecting its recovery, maintaining its pest-free status and allowing natural processes to shape the ecosystem.
How Moutohora recovered after introduced pests were removed
Moutohora, known as Whale Island, was once damaged by introduced goats, rabbits, sheep, cats and Norway rats. The island was described as bare soil and rock in its most degraded state. Once the last mammalian pests were eradicated in 1987, the island began to recover more rapidly. Moutohora (Whale Island) Wildlife Management Reserve ecological restoration plan records a shift from grass-dominated land to regenerating native forest. Planting added more than 11,000 plants from 45 species between 1984 and 1989. The island supported richer vegetation and recovering wildlife.
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How pest removal allowed Moutohora’s native vegetation to return
The transformation began with the removal of animals that had reshaped the island. Rabbits were eradicated in 1987 after years of control. More than 1,000 goats were shot in 1964, and eradication was achieved in 1977. Sheep were removed in 1943, while cats were also eliminated. Norway rats were eradicated in 1986, and the island was declared pest-free in 1987. Thirteen years after mammalian pests were eradicated, the kuia population had doubled. The change allowed native vegetation to expand across areas that were once dominated by grass.
How Moutohora’s plant life recovered after decades of damage
The return of native vegetation was supported by a planting programme that began in 1984 and ended in 1989. More than 11,000 plants representing 45 species were established. The work aimed to encourage natural regeneration, strengthen plant populations, create fire-resistant buffer zones and provide more food and habitat for wildlife. The island has a mosaic of pōhutukawa forest, māhoe forest, kānuka scrubland, fern cover and grasses. It records 190 indigenous plant species and 110 exotic species.
How Moutohora became a home for reintroduced species
Restoration also created conditions for threatened species to return. A programme introduced 11 threatened plant species to Moutohora, with six establishing self-sustaining populations. The island has also supported reintroductions of animals. Forty tīeke, or North Island saddleback, were released in 1999. Within the first year, 37 were seen again, and eight pairs were identified. A 2005 survey estimated about 1,000 tīeke on the island, although the plan noted uncertainty around that figure. Tuatara were also moved to Moutohora in two stages. It describes habitat and evidence of island-born juveniles, while calling for continued long-term monitoring.
Restoration and protection of Moutohora
Moutohora’s restoration approach focuses on protecting the island from renewed pressures while allowing natural processes to continue wherever possible. The plan calls for biosecurity, continued monitoring and assessment before any new species are introduced. It identifies research needs, including further work on tuatara, lizards and kiwi nesting failure. Moutohora covers 143 hectares and is a remnant volcano in the Bay of Plenty. Its restoration has changed the character of the island.