New Zealand’s subantarctic islands consist of five isolated island groups scattered in a 700-km-wide semi-circle to the south and east of the South Island. The five groups are:
- the Snares Islands, the smallest in land area and the closest to the mainland
- the Auckland Islands, the largest group, with the longest human history, about 460 kilometres due south of Fiordland
- Campbell Island, the second-largest and most southerly island
- the Antipodes Islands, which are further east, almost due south of East Cape, and have the third-largest land area
- the Bounty Islands, the most easterly and northerly of the subantarctic islands.
When New Zealand formally became a British colony in November 1840, its boundaries were set at latitude 34° 30' ‘north’ (an error – it should have been south) and 47° 10' south, and longitude 166° 5' to 179° east. None of the subantarctic islands were included. In April 1842 new letters patent designed to include the Chatham Islands moved the boundaries to 33° and 53° south, 162° east and 173° west – thus including all the islands. Ten years later in the Constitution Act, the southern boundary was changed again – to 50° south. This included the Snares, Bounty and Antipodes but not the Auckland and Campbell islands. Finally, when control of the Auckland Islands became an issue in 1861, it was decided to return them to New Zealand. By an imperial act of 18 June 1863 the southern boundary was restored to 53° south.
New Zealand territories
A sixth island, Macquarie, further south and west, and ecologically similar, is part of Australia, although it is actually closer to New Zealand and New Zealand tried to acquire it in 1890. The other five island groups have been part of New Zealand territory since 1863. Their links have always been closest with Southland.
In the 2000s the subantarctic islands were uninhabited nature reserves. Yet for some 700 years there were spasmodic efforts by people to settle on the larger islands. Only one group (Māori from the Chatham Islands) succeeded in living there more than five years. Instead the islands have returned to the natural world.
Climate is the main reason for both the islands’ inhospitality to people and their rich natural environment. Lying in the roaring forties and furious fifties, remote from any land mass, they face a barrage of fronts coming in from the west. The climate is wet, cold, windy and very cloudy.
Thomas Musgrave, shipwrecked on Auckland Island in 1865, described ‘incessant gales, constant hail, snow and pelting rain’.1 Ron Balham, a meteorologist stationed on the Auckland Islands in the 1940s, concluded, ‘It was a shocking climate – after all it was overcast 95 percent of the time, the wind velocity was frequently force 6 on the scale, and the cloud cover about 95 percent, the humidity about 95 percent’.2 Little wonder that people chose not to live there.
On Campbell Island there are winds of over 63 km per hour on 280 days a year. Its 660 annual hours of sunshine are less than a third of that in Christchurch or Wellington. On average there are less than 12 hours of sunshine in June – and in June 1970 only 1.5 hours were recorded.
Rainfall in the islands is not torrential but frequent. Campbell Island receives an average of 1,360 mm a year (about the same as New Plymouth), but it rains on 300 days, and snow falls on the higher ground, though it does not usually settle for long. Rain is heavier on the Auckland Islands, lighter on the Antipodes. Sitting between the Antarctic and subtropical oceanic convergences, the temperatures are maritime, with little annual or daily variation. Mean annual temperatures range from 11°C on the Snares to 7°C on Campbell Island.