It is present in all available habitats on Kapiti, including mature broadleaf forest, regenerating forest and grassland (Marchant and Higgins 1990). It eats invertebrates, but also fallen fruits and leaves (Heather and Robertson 2015). It lays one, sometimes two eggs, usually in a burrow. Chicks hatch fully-feathered, and first leave the nest unaccompanied after about a week. It normally begins to breed at around three years of age (H. A. Robertson in litt. 1999). Mean life expectancy is estimated at 45 (27-83) years (Robertson and Colbourne 2004).

Apteryx owenii (or allied species) occurred in forested areas throughout New Zealand prior to European settlement, but A. owenii is now restricted to eight offshore islands to which it has been introduced, and three mainland sites where it has been reintroduced (Germano et al. 2018). The stronghold is Kapiti Island (20 km²), where five birds are believed to have been introduced in 1912 (Ramstad et al. 2013). In the 1980s, birds were released on Red Mercury (2 km²), Hen (5 km²) and Long Islands (2 km²), and to Tiritiri Matangi Island (2 km²) in 1993 and 1995 (Colbourne and Robertson 1997). Birds have also been released on Motuihe Island (2 km²) in 2009 (Anon. 2009), Chalky Island (5 km²) in 2008-2010 (Edmonds 2010), Anchor Island (15 km²) in 2015-16 (ongoing) and at Cape Sanctuary (1 km²) near Napier in the North Island (ongoing). Birds were also reintroduced to Shakespear Open Sanctuary in 2017 (Germano et al. 2018).

Conservation Actions Underway
Translocations to predator-free offshore islands have done much to secure the survival of A. owenii, and the species has been reintroduced to three mainland sites (Germano et al. 2018). More islands have been examined for further introductions, but given the health of the present island populations, and their geographical spread, there is limited need for additional island populations; however, other secure mainland sites are being investigated to allow people access to the species. Research has shown that neither of the D'Urville Island birds placed on Long Island (Marlborough Sounds) with two Kapiti Island birds has left any descendants and so the entire population is derived from a single pair and is highly inbred (Taylor 2014). Two hybrid offspring from A. owenii x A. rowi pairings have been discovered in South Okarito forest since 1993, suggesting that A. owenii must have been present in the area until the mid-1990s and so nearby reports of kiwi are being checked, and elsewhere in the South Island, young (i.e. small) A. haastii are critically examined in case a few A. owenii persist on the South Island mainland. All populations are monitored using call-counts, and territory-mapping, and specially-trained dogs are used to locate banded birds (H. A. Robertson in litt. 2016). To reduce the risk of inbreeding depression and increase genetic diversity, 10 birds each from Tiritiri and Red Mercury were replaced with individuals from Kapiti, with the removed individuals used to establish populations at Cape Sanctuary and Shakespear Open Sanctuary (Robertson et al. 2019).

Conservation Actions Proposed
Continue regular monitoring of all island populations. Enforce measures to prevent the introduction of non-native mammals to occupied islands and mainland sites. Manage genetics by carrying out further translocations to achieve a minimum of 30, preferably 40, founders for each island/mainland population, ensuring that populations reach the necessary level of genetic diversity for long-term survival (Germano et al. 2018). Given that there is a large risk of inbreeding depression, locating surviving individuals in populations assumed to be extinct could also be invaluable to improving genetic diversity (Ramstad et al. 2021). Test whether a population can be established without a predator exclusion fence in a predator-managed site on the mainland (Germano et al. 2018).