Motu Kaikōura is special in many ways. It is located next to Aotea/Great Barrier Island, almost closing off the Port Fitzroy Harbour, which has two entrances: the northern entrance is approximately 300 metres wide at its narrowest while the western entrance is only 80 metres at its narrowest. These narrow gaps between Motu Kaikōura and the larger island present challenges to keeping the island pest-free.
This page includes brief summaries of various scientific studies that have taken place on the island with direct links to reports which are also found on the reports page of this website. Currently this page has information about the island’s Archaeology, Botany, Geology, Moths and Pond Life.
Geology
In 2023 Dr Bruce Hayward, CNZM FRSNZ visited the island and prepared a report on the Geology and Geoheritage of the Island. The island is a remnant of an andesite stratovolcano that erupted 12 to 15 million years ago. Breccias, probably the result of lahars, interbedded with andesite lava flows are a feature of the island. Over the millions of years since the eruption ceased there has been much erosion and more recently there has been an uplifting of several hundred metres as well as tilting down to the east. The highest point of the island is Kōhatu Tītore (Mitre Peak), an exfoliation dome at 185 metres above sea level.
Dr Hayward’s report identifies two regionally significant geoheritage sites:
- Man of War Passage, the narrow gap between Motu Kaikōura and Aotea/Great Barrier Island. During the last Ice Age it was a dry saddle connecting the now separate islands, the saddle being drowned as sea level rose after the Ice Age ended.
- West Point, a large intrusion with columnar cooling joints.
In addition the report identifies 20 locally significant sites.
Archaeology
In 2005 Andy Dodd and Vanessa Tanner undertook an archaeological survey of the island and prepared a report Kaikoura Island Archaeology Survey. Both the report, pages 7-18, and the Management Plan, 2020, pages 22-26, give a brief history of human settlement of the island, including a chronology on pages 16-18 of the former. Evidence suggests that the island was in use by Māori by about 1400 and continuously in use by various iwi until it was sold to Pakeha in the middle of the 19th century. Since its occupation by Pakeha the island was gradually turned into farmland with sheep, cattle and deer the main domestic mammals but feral pigs and goats were also introduced. Some earthworks were also undertaken, especially access tracks and the airfield near the top of the island. There has also been some erosion. As a result many archaeological sites have been degraded over time. Nevertheless some features remain, especially the following:
- two pā sites
- stone walls and terraces
- middens
- World War II defence bunkers and buildings
- farming remnants, including a house platform and dams.
Botany
Before the Trust took over the management of the island it had gone through over a century of farming and related activities resulting in a lot of degradation of its flora. A deliberate decision was made to remove the browsing mammals but otherwise allow the vegetation to recover naturally with no planting to enhance the recovery. Botanical surveys have taken place periodically. To set the base a major botanical survey led by Ewen Cameron took place in December 2006. His report, based on that survey as well as several subsequent visits to the island in 2007 and published in the Auckland Botanical Society Journal, presents the botanical state of the island soon after the Trust was formed and before all of the browsing mammals had been removed.
Subsequent visitors to the island have observed plants not on Cameron’s list. For example the report by Rosemary Barraclough and others describes some recent discoveries.
Pond Life
In the farming days of the island a pond was created in one of the valleys. During December Dr Brian Gill collected samples from the pond and analysed them. He notes that freshwater microscopic algae and protozoa tend to be largely cosmopolitan, based on their ease of spread in dirt on the feet of aquatic birds, and perhaps via wind. This means that ponds throughout New Zealand will have similar microscopic organisms and this is confirmed as he reports in
Microscopic pond life of Motu Kaikoura: observations in December 2025.
Moths
In December 2024 Sean Clancy, an ecologist based in the UK specialising in Lepidoptera, visited Motu Kaikōura and collected over 100 different species of moths, including some rare endemic species. His report published in Newsletter 53 of the Moths and Butterflies of NZ Trust, Winter 2025, pages 8-9, comments on the importance of moths as a readily available and reasonably accessible window into the biodiversity present within a site as well as being indicators of the effect of climate change. The Newsletter is included here courtesy of the Moths and Butterflies of NZ Trust.