|Scientific Name:||Apteryx owenii|
|Species Authority:||Gould, 1847|
|Red List Category & Criteria:||Near Threatened ver 3.1|
|Reviewer/s:||Butchart, S. & Symes, A.|
This species is listed as Near Threatened owing to the success of intensive conservation intervention which has established populations on five islands and one mainland site, in which numbers continue to increase or remain stable. Given the wide geographic spread of these populations the species is under no immediate threat, but populations, and the predator free status of the islands on which they live, still require monitoring.
|Range Description:||Apteryx owenii occurred in forested areas throughout New Zealand prior to European settlement, but is now restricted to seven offshore islands to which it has been introduced, and one mainland site where it has been reintroduced (H. A. Robertson in litt. 1999). The stronghold is Kapiti Island (20 km2), where birds are believed to have been introduced in the early 1900s. 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). Recently birds have also been released on Motuihe Island in 2009 (Anon. 2009) and Chalky Island in 2008 and 2009 (Edmonds 2010). The population was estimated at 1,500 individuals in 2008 (Holzapfel et al. 2008), with 1,200 on Kapiti and 300 spread amongst the other populations. This is an increase from 2000, when the population was estimated at 1,150 individuals (2000) (Robertson and Colbourne 2004). On Kapiti the species is considered to be at carrying capacity and annual survivorship is estimated at 97.5% (Robertson and Colbourne 2004). This population is being used to increase populations on other islands or to establish new populations (Holzapfel et al. 2008). At the same time more recently established populations are increasing.|
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||The population is estimated to number at least 1,200 individuals in total, roughly equivalent to 800 mature individuals.|
|Habitat and Ecology:||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 1997). It lays just one egg, 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).|
|Major Threat(s):||Introduced predators are absent from all the islands except Weka Gallirallus australis, which was introduced to Kapiti prior to A. owenii. There are conflicting reports as to the extent and effect of predation (Jolly 1989, Marchant and Higgins 1990), although the A. owenii population appears very healthy (H. A. Robertson in litt. 1999). The island populations remain susceptible to accidental or deliberate introduction of mammalian predators.|
Conservation Actions Underway
Translocations to predator-free offshore islands have done much to secure the survival of A. owenii. 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. The genetic diversity of the species is being assesed to determine if they are severely bottlenecked and whether it might be possible to increase their genetic diversity by introducing new blood lines from Long Island, since currently all reintroduction birds are sourced from Kapiti Island (which may have had only five founders) (H. A. Robertson in litt. 2007). A small captive-breeding population is held, primarily for public education purposes (Heather and Robertson 1997, Robertson in prep). All populations are monitored using call-counts, and specially-trained dogs are used to track banded birds (H. A. Robertson in litt. 1999). Conservation Actions Proposed
Continue regular monitoring of all island populations. Enforce measures to prevent the introduction of non-native mammals to occupied islands.
|Citation:||BirdLife International 2012. Apteryx owenii. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 23 May 2013.|
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