Data Zone
Justification of Red List category
This species is rapidly declining as a result of predation by introduced species, with the rate of population reduction suspected to have exceeded 30% over the past three generations and to continue at this rate into the future. It is therefore assessed as Vulnerable.
Population justification
The 2013 total population was estimated at 21,350 birds (Heather and Robertson 2015), down from previous estimates of 27,225 (± c.25%) birds in 1996 (Robertson 2003) and 29,800 birds in 2008 (Holzapfel et al. 2008). The population was estimated to number 24,850 individuals in total in 2018 (southern Fiordland 3,900, northern Fiordland 8,200, Stewart Island 12,300, Haast 450) (Germano et al. 2018), roughly equivalent to 16,500 mature individuals.
Trend justification
This species is inferred to be declining as a result of introduced predators and this trend is predicted to continue (Robertson et al. 2021). The populations in northern and southern Fiordland are thought to be declining in the range 30-70% and 50-70% respectively (Robertson et al. 2021). The majority of the species is not currently receiving active conservation management and these unmanaged populations are thought to be declining by 2% per year (Germano et al. 2018). The total number of individuals is thought to have decreased from 29,800 in 2008 to 24,850 in 2018 based on estimates in Innes et al. (2015) projected to 2018, and is suspected to decrease further to 21,550 by 2030 with existing levels of management (Germano et al. 2018) which is equivalent to a c.46% decline within three generations. Recent research suggests the population on Stewart Island may be stable as previously detected declines at Mason Bay are likely to have been localised (Robertson et al. 2021). However, given the steep ongoing declines in the southern and northern Fiordland populations, it remains plausible that the global rate of decline exceeds 30% within three generations. Only the small Haast population is increasing - this population was reported as 225 individuals in 1996 (Robertson 2003), but intensive pest control and ex-situ hatching of wild-sourced eggs and chick-rearing in predator-free crèches, and the establishment of small populations at pest-free mainland and island sites has resulted in a growth to 350 birds in 2013 (Robertson and de Monchy 2012, Heather and Robertson 2015) and 450 birds in 2018 (Germano et al. 2018).
Apteryx australis is restricted to Fiordland and Stewart Island, with an isolated population near Haast, New Zealand. Some birds from the Haast population have been established since 2000 at a pest-free mainland sanctuary (Orokonui, Ecosanctuary near Dunedin) and on three pest-free islands (Pomona, Coal and Rarotoka). Northern Fiordland birds occur from near Milford Sound to Doubtful Sound and Lake Manapouri, including Secretary Island. Southern Fiordland birds are found from Doubtful Sound and Lake Manapouri to near the southern coast of Fiordland, including Resolution Island and several smaller islands in Dusky Sound where birds were introduced over 100 years ago (Colbourne 2005). The two Fiordland taxa overlap in a narrow zone north of Wilmot Pass (H.A. Robertson in litt. 2016). Stewart Island birds are found throughout the main island, though they are scarce north of Paterson Inlet and the Ruggedy Mountains (Heather and Robertson 2015). Some have been introduced to Ulva Island since 1950 and a few are present on Pearl, Bravo and Owen islands (Colbourne 2005, Heather and Robertson 2015, H.A. Robertson in litt. 2016).
It occurs in a variety of habitats ranging from coastal sand dunes on Stewart Island to forest, subalpine scrub and tussock grasslands in Fiordland. It feeds primarily on invertebrates but fallen fruit and leaves are also taken. It lays just one egg, usually in a burrow (Marchant and Higgins 1990, H.A. Robertson in litt. 1999). The incubation period is amongst the longest for any bird at between 74 and 84 days (Calder et al. 1978). Chicks hatch fully-feathered, and first leave the nest unaccompanied after about a week. In Fiordland and Stewart Island populations, young remain with their parents for years (up to 7) but at Haast they are independent at about 1-2 months old. It is long-lived, with mean life expectancy of adults of 27-45 years (Robertson and de Monchy 2012, Tansell et al. 2016, H.A. Robertson in litt. 2016).
The impact of introduced predators is the greatest threat and is causing rapid population declines (Robertson et al. 2021): Stoat Mustela erminea eat eggs and chicks up to c. 1,000 g, feral cats Felis catus eat chicks and juveniles up to c.1,200 g, and dogs Canis familiaris, ferrets M. furo, and Common Brushtail Possum Trichosurus vulpecula kill juveniles and adults (McLennan et al. 1996, McLennan et al. 2004). Predation pressure is possibly lower on Stewart Island where mustelids are absent, and dogs are prohibited from most of the island (H.A. Robertson in litt. 1999). However, feral cats are widespread and common (H.A. Robertson in litt. 2012). The rate of loss of native habitat has declined markedly but this is not currently considered a driver for population reductions (Robertson et al. 2010). Avian diseases and pathogens are a potential threat, particularly with chicks held in captivity or in high-density crèche sites. The Haast population is at risk from stochastic events due to the small population size and isolation and suffers from low fecundity (Holzapfel et al. 2008).
Conservation Actions Underway
Monitoring is nationally coordinated, and uses call-counts, specially-trained dogs searching for banded birds, and radio-tracking (Holzapfel et al. 2008). Intensive management involving predator control and removing and incubating eggs and returning subadults once large enough to fend off predators is taking place within the Haast population. The latter approach has been used at Haast since 1995 under the name Operation Nest Egg (ONE) (Colbourne et al. 2005), and has succeeded in increasing the population of A. australis 'Haast' (Holzapfel et al. 2008, Robertson & de Monchy 2012) which is now thought to number 450 birds in total (Germano et al. 2018). Research has focused on the Haast, Clinton valley, Murchison Mountains and Stewart Island populations, and involves taxonomy, investigating the effects of predators and their management, ecology and the social structure of populations (Robertson and de Monchy 2012, Tansell et al. 2016, H.A. Robertson in litt. 2016).
Conservation Actions Proposed
Increase the proportion of the kiwi population that is managed and control predators at a landscape scale to produce growth rates of 2% per year or greater (Germano et al. 2018). Measure the response of kiwi to management to determine optimal landscape-scale management (Germano et al. 2018). Survey populations in Fiordland and undertake population modelling of all taxa. Clarify the taxonomy of the species. Research reasons for low productivity in the Haast population. Evaluate the success of translocations and support the development of a structured captive breeding programme; Collar and Butchart (2013) suggest that captive breeding should be considered although conversely, is not considered useful by the Recovery Team (Holzapfel et al. 2008). Intensively manage the Haast population and at least one other mainland population using the ONE programme with the goal of doubling the population (Holzapfel et al. 2008). Investigate landscape-scale remote monitoring techniques for sparse populations (Holzapfel et al. 2008). Maintain the mustelid-free status of Stewart Island and investigate the possibility of eradicating cats from the island (H.A. Robertson in litt. 2016). Promote legislative and policy changes to protect populations and encourage high-quality advocacy at all levels (Robertson 1998, Holzapfel et al. 2008). Educate and inform the public and encourage community involvement in kiwi conservation (Robertson 2003, Holzapfel et al. 2008).
40 cm. Medium-sized kiwi, flightless, no visible wings. Dark greyish-brown (Fiordland population), rufous-brown (Haast), dark brown (Stewart) feathers streaked lengthways with reddish-brown. Long ivory bill. Voice Shrill, clear ascending then descending whistle (male), lower-pitched, hoarse cry (female). Hints Loud calls at night, especially first two hours of darkness.
Text account compilers
Vine, J.
Contributors
Robertson, H.A.
Recommended citation
BirdLife International (2024) Species factsheet: Southern Brown Kiwi Apteryx australis. Downloaded from
https://datazone.birdlife.org/species/factsheet/southern-brown-kiwi-apteryx-australis on 23/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 23/12/2024.