VU
Southern Brown Kiwi Apteryx australis



Justification

Justification of Red List Category
Mainland populations of this species are declining by 1-2% per year because of poor recruitment due to predation of chicks, mainly by introduced stoats. The overall trajectory of the large Stewart Island population is unclear because the 2.2% per annum decline in the number of territories in the only study population, at Mason Bay, may be due to predation by introduced feral cats, or, more likely, to habitat change at that particular site. The overall decline of the species warrants Vulnerable status.

Population justification
The 2013 total population was estimated at 21,350 birds (Heather & 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 isolated and genetically distinctive Haast 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 & de Monchy 2012, Heather & Robertson 2015). The species is still common in localised areas in Fiordland (9000 birds) and in central and southern parts of Stewart Island (12,000 birds) but is thought to be declining (Heather & Robertson 2015). Stoat trapping in the Murchison Mountains resulted in a doubling of chick survival, and this turned a population decline of 1.6% per year into a gain of 1.2% per year (Tansell et al 2016). In 125 ha of abandoned farmland at Mason Bay, Stewart Island, the tokoeka population dropped from 17 pairs in 1993 to 11 pairs in 2013 (2.2% per year), but it is not clear if this has been driven by recruitment failure through predation of chicks by feral cats, or by habitat loss as flax, tussock and scrub reclaim former grassland feeding sites.

Trend justification
The species is common on Stewart Island but is thought to be declining (from c.20,000 birds in 1996 [Robertson 2003] to 15,000 in 2008 [Holzapfel et al. 2008]) and in localised areas in northern Fiordland (10,000 birds) and southern Fiordland (4,500 birds) (Heather and Robertson 1997, Holzapfel et al. 2008). The inferred decline of 5.8% per year on the mainland, like its congener A. mantelli (McLennan et al. 1996), is now considered to have been much too pessimistic, and the actual rate of decline is thought to be closer to 2% (Holzapfel et al. 2008). The generation length used here may need to be revised, with possible implications for the inferred rate of decline.

Distribution and population

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. 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 & 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 & Robertson 2015, H Robertson in litt. 2016).

Ecology

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 parent s 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 & de Monchy 2012, Tansell et al. 2016, H. Robertson in litt. 2016).

Threats

The impact of introduced predators is the greatest threat: stoat Mustela erminea eat eggs and chicks up to c.1000 g, feral cats eat chicks and juveniles up to c.1,200 g, and dogs, ferrets M. furo, and brush-tailed possums T. vulpecula kill juveniles and adults (McLennan et al. 1996, McLennan 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 and this is not currently considered a driver for population reductions (Robertson 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

Conservation Actions UnderwayMonitoring 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). 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 & de Monchy 2012, Tansell et al. 2016, H. Robertson in litt. 2016).


Conservation Actions Proposed
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. 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).

Identification

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.

Acknowledgements

Text account compilers
Benstead, P., Mahood, S., Martin, R, McClellan, R., Taylor, J., Stringer, C.

Contributors
Robertson, H., Weeber, B.


Recommended citation
BirdLife International (2019) Species factsheet: Apteryx australis. Downloaded from http://www.birdlife.org on 20/04/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 20/04/2019.