Ngāwhatu Kai-ponu / The Brothers
Last Modified: 27-3-2020 15:26
By: Christopher Cookson
Ngāwhatu Kai-ponu / The Brothers are a pair of small rocky islands and surrounding rocks in Cook Strait off the east coast of Arapaoa Island that are the eastern most point in Marlborough. The northernmost of the two islands has an area of four hectares, while the southernmost island has an area of eight hectares. Although South Brother Island is larger, it has lower elevation above sea level. The Māori name Ngāwhatu-kai-ponu refers to the eyeballs of the giant octopus the Polynesian explorer Kupe battled according to tradition. The islets were considered tapu to Māori, and it was considered bad luck for paddlers making their first crossing of Raukawa / Cook Strait to see the islands, so they were blindfolded.
During Captain Cook's first visit to Cook Strait, the Endeavour was very nearly wrecked on the Brothers, as a lack of wind and strong tide drove the ship towards the rocks.
North Brother Island has a wooden lighthouse that was constructed in 1877, along with accommodation built for the lighthouse keepers. Construction was made extremely difficult by rough seas, hard ground, and the lack of any safe anchorage, and took almost a year. The light was originally oil powered until 1954 when it was replaced with an electric light powered by diesel generator, and eventually a halogen lamp powered by batteries and solar panels. For a time, the lighthouse was manned by four keepers, although this was eventually reduced to two. The lighthouse was fully automated in 1990.
All supplies for the lighthouse keepers, including drinking water, had to be supplied initially by sea, although later a heli-pad was established. Due to the lack of any form of safe landing for vessels, supplies were landed by crane. Due to the hazardous landing and confined space, families were not permitted to reside on the island. Keepers worked a roster of a month on, and two weeks off the island. The confinement and isolation was generally not popular with staff, with mental health issues affecting many.
The Brothers lighthouse was the last manned lighthouse in New Zealand.
The islands are managed by DOC, as a wildlife sanctuary and public access is not permitted. Even DOC staff must carry out extensive decontamination procedures to ensure no foreign species are introduced to the islands.
Geology and Climate
The Brothers Islands are principally composed of schist rock, with little soil, although some limited areas of peaty soil and extensive areas of gravel exist. Rainfall is over 1000mm per year, and the islands are frequently subject to strong winds.
North Brother Island has over twenty species of native plants with Coprosma repens scrub and a native iceplant Disphyma australe as the dominant plant species. Other significant species include Senecio lautus, Sarcocornia quinqueflora, Hebe elliptica, Elymus rectisetus, and Muehlenbeckia complexa. An endangered plant Kirkianella aff. Novae-zealandiae is found only in one other location in New Zealand besides North Brother Island. Plant species on the islands are adapted to high salinity due to the exposed nature of the islands and strong winds which result in frequent salt spray.
The Brothers Island tuatara (Sphenodon guntheri) is found on the North Brother Island along with a variety of geckos and skinks. Bird species include Fairy Prions, Blue Penguins, and Common Diving Petrels which nest on the island in burrows.
In spite of their isolation, several pest plant species have established on the islands, with tree mallow a significant invasive species that DOC runs an eradication programme for.