A dense forest cover shelters numerous rare or endangered animal species. In February 2013, there were reports of the critically endangered
New Zealand storm petrel (
Oceanites maorianus) breeding on the island. feeding in a
coprosma tree on Little Barrier Island When Māori occupied the island, as much as a third of the island was cleared of forest. However, since the acquisition of the land by the New Zealand government, all but 20
hectares of the island have been reforested. In 2012, there were reports that a southern right whale may have
calved near the island. The island was, until recently, the last refuge for two species: the
stitchbird and the
wētāpunga. By 1883, the stitchbird was confined to Little Barrier Island due to
introduced species and
deforestation on the mainland. Thanks to the actions of
Department of Conservation, the species has been reintroduced to several other offshore islands as well as some mainland sanctuaries that have predator-proof fences, such as the
Bushy Park forest reserve. The wētāpunga, on the other hand, has been confined to this island since its extinction in the
Northland and
Auckland regions sometime in the 19th century. The last population continued to decline until the removal of
kiore in 2004. Since then, the population has made a rapid recovery, and the species has been reintroduced to numerous predator-free places and islands as well.
North Island brown kiwi (
Apteryx mantelli) live on Little Barrier Island. They were reported from there over a number of decades in the 19th century, but with no tangible evidence for a long time. Then, the naturalist
Andreas Reischek collected an
Apteryx mantelli there in 1882. Many years later, examination of the feathers of the specimen, which was held in the
Natural History Museum, Vienna, yielded the louse
Rallicola rodericki, which is known only from
Apteryx mantelli living on Little Barrier Island, providing supporting evidence for the provenance of that specimen kiwi. The island's native population was supplemented with additional
Apteryx mantelli that were transferred from the North Island in the early 20th century. There are several invertebrate species that are only known from this island, namely the ground beetle
Mecodema haunoho and the spiders
Migas insularis and
Stanwellia hapua.
Kākāpō (night parrots), also critically endangered, were first translocated to the island in 1982. They successfully bred there in the 1980s and 1990s with the support of supplementary food. They were all removed in 1999 so that
kiore (Polynesian rats) could be eradicated from the island using poison bait. They were reintroduced in 2012; as of July 2017, their population on the island stood at 14. Hauturu is a test site to see if the kākāpō can breed and raise their young successfully without human intervention.
Invasive species The Polynesian rat or kiore (
Rattus exulans) was likely introduced as
invasive species during the initial settlement of the island by Māori. 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. German wasps had been reported on the island by the 1980s. A potential relationship between rat eradication and decline in
Vespula species has been reported, but no such link was found in later work. Prior to 1995, very little attention was paid to weed species on the island. 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. The main target species were
climbing asparagus, the
Mexican devil, and the
mist flower. ==Climate==