Mana Island, near Wellington, is one of Aotearoa New Zealand’s conservation success stories. Farmed for more than 150 years, the island is now covered with forest that is overflowing with an abundance of endemic birds, lizards and insects. Using pairs of images taken 50 years apart, natural history curator Dr Colin Miskelly describes how and why the island was transformed from a farm to a thriving sanctuary.

Special lizards

Tony Whitaker (1944–2014) was a science technician working for Ecology Division, Department of Scientific and Industrial Research, when he first visited Mana Island in June 1972. He was already a leading authority on New Zealand lizards, and made two remarkable discoveries that month: species that were subsequently given the names McGregor’s skink and goldstripe gecko. The skink discovery was particularly noteworthy, as the nearest population is on a tiny island off Whangarei (where Whitaker himself had discovered them in 1968).

The DSIR team also confirmed that Cook Strait giant wētā had survived on the island, and that mice were the only pest mammals present. The absence of rats and stoats greatly increased the conservation potential of the island.

Before and after images

In addition to these biological discoveries, Whitaker took a series of images of Mana Island, which were among the thousands of images gifted to Te Papa by his wife, Vivienne, in 2020. With the 50-year anniversary of these images looming, I sought permission from the Department of Conservation to visit Mana Island in June 2022, to retake the images from the same vantage points. These paired images illustrate the profound changes on Mana Island since Whitaker’s first visits.

Unexpected management regime changes

In 1972, Mana Island had been a Crown-leased sheep farm for more than 100 years. Unbeknown to the visiting scientists or the lease-holder, the government was poised to take over the lease, in order to manage the island as a quarantine research station for exotic sheep breeds.

Between 1973 and 1978, the Ministry of Agriculture and Fisheries invested the equivalent of more than $26 million in infrastructure on the island, building three houses, a wharf with overhead lighting, a research laboratory and numerous farm buildings, installing three diesel generators, and erecting many kilometres of fencing. This huge investment in the improvement of New Zealand’s sheep flock came to a shuddering halt in 1978. All 2,000 sheep were slaughtered and buried after an outbreak of scrapie disease (the sheep equivalent of mad cow disease).

The Department of Lands & Survey ran dairy bulls on the island through to 1986, when the decision was made that the island should be used solely for conservation purposes.

Creating a forest – and getting rid of the mice

The removal of the last farm stock from Mana Island in April 1986 was the precursor of a major revegetation programme. Between 1987 and 2011, close to 443,000 trees were planted on the island, using local seed sources. And in 1989, Colin Ryder (from the Wellington branch of Forest & Bird) led a successful mouse eradication project – the largest in the world at the time.

Planting was first attempted in the sheltered gullies, before moving up onto the wind-swept plateau. Planted forest now covers about 37% of the island, merging seamlessly with the original 4-hectare forest patch, and natural regeneration on the coastal slopes.

Restoring the wildlife

With the mice gone and a forest created, Mana Island became suitable for a great diversity of endemic wildlife. Some species found their own way to the island (e.g. the tūī, pūkeko and pied shags that are now breeding there, and the visiting kererū and kārearea), while many others were introduced as part of a comprehensive ecological restoration programme.

The full project, with many more images, is described in detail in ‘From farm to forest – 50 years of ecological transformation on Mana Island, New Zealand’, published in Te Papa’s journal Tuhinga.

Acknowledgements

With many thanks to Vivienne Whitaker, Maarten Holl, Leon Berard, and Don Newman for providing images and supporting their reproduction here and in the Tuhinga article. The Department of Conservation, Ngatitoa Rangatira, and the Friends of Mana Island are acknowledged for their ongoing commitment to the ecological restoration of Mana Island.