By 1881 only a few Ngāti Wai were still living there and the British Crown attempted to buy the island in order to turn it into a nature reserve.

[4] Māori stonework has been found in fourteen locations on the island, primarily around the coastal flats at Te Titoki Point.

Man-made cuttings, which were described in 1895 as ruts for hauling canoes, can be seen on the boulder beach ridge at Te Titoki Point.

The most extensive stonework is located in the northwest of the island, near the ridge south of Te Hue Stream, where it is spread over several hectares.

[12] The island is steeply sloping, and deeply dissected by ravines radiating from a central range that peaks at Mount Hauturu whose altitude is 722 m (2,369 ft).

[14] Approximately 18,000 years ago during the Last Glacial Maximum when sea levels were over 100 metres lower than present day levels, Little Barrier Island was landlocked to the North Island, surrounded by a vast coastal plain where the Hauraki Gulf / Tīkapa Moana exists today.

Sea levels began to rise 7,000 years ago, after which Little Barrier became an island separated from the rest of New Zealand.

[4] The island has been identified as an Important Bird Area by BirdLife International because it is a nesting site for vulnerable Cook's and Parkinson's petrels.

[16] In February 2013, there were reports of the critically endangered New Zealand storm petrel (Oceanites maorianus) breeding on the island.

[20][21] The island is home to two endemic insect species, the ground beetle Mecodema haunoho,[22] and Deinacrida heteracantha, also known as the Little Barrier giant wētā.

The Polynesian rat or kiore (Rattus exulans) were likely introduced as invasive species during the initial settlement of the island by Māori.

[7] As in other places where predatory species were introduced, small animals not accustomed to predation likely experienced a decline in population, being pushed towards endangerment or extinction.

The rangers' garden had been planted in exotics, and bird and wind dispersed colonising species that spread rapidly.

In 1996 a weed control programme, based on the successful work on the Kermadecs, was implemented with teams of weeders grid-searching the island.