NT
South Island Saddleback Philesturnus carunculatus



Justification

Justification of Red List Category
This species has a small population confined to a number of predator free islands and one secure mainland site in South Island, New Zealand. Owing to intensive conservation management the population is increasing. It is considered Near Threatened because it only occurs at a small number of sites and is therefore moderately susceptible to stochastic events and human impacts.

Population justification
Hooson and Jamieson (2003).

Trend justification
This population is observed to be increasing owing to documented translocations and intensive conservation action (Higgins et al. 2006). In 2003 the population was estimated at 1,265 individuals but in 2013 it was considered to be more than 2,000 birds (Masuda and Jamieson 2013).

Distribution and population

Philesturnus carunculatus was once widespread through the South and Stewart Islands, New Zealand. Predation by introduced mammals (mainly ship rats) led to their extinction on the South Island and Stewart Island by about 1900, and they became confined to the South Cape Islands (Big South Cape, Solomon and Pukeweka Islands), islands off the south-west coast of Stewart Island (Merton 1975, Heather and Robertson 1997). When ship rats invaded all three islands in the early 1960s, the Wildlife Service (which subsequently became part of the Department of Conservation) successfully moved birds from Big South Cape Island to nearby Big and Kaimohu Islands in 1964, thereby averting the extinction of this species. They have now been translocated to c20 offshore islands and one mainland sanctuary (Masuda and Jamieson 2013), and the three original 'donor' island populations have become extinct. Rats have now been exterminated from Big South Cape, and South Island Saddleback has been reintroduced to the island (Masuda and Jamieson 2013). 

Ecology

It inhabits native forest, nesting in tree holes, rock crevices, tree-fern crowns and dense epiphytes, usually close to the ground. Whilst it also occurs in replanted forest, it is thought that mortality is higher in this habitat (Brunton and Stamp 2007). It forages in leaf litter and deadwood, predominantly on invertebrates, but will also take fruits and nectar (Taylor and Jamieson 2007). It is not a strong flier and bounds between branches or along the ground rather than taking long flights. It usually raises one brood in October-January but will nest up to four times at recently colonised sites where resources are not limiting.

Threats

Introduced carnivorous mammals probably caused its extinction on the mainland. The arrival of black rat Rattus rattus on the three Stewart Island islets in 1963 caused the rapid extinction of the populations. P. carunculatus cannot coexist with brown rat R. norvegicus or Pacific rat R. exulans (Lovegrove 1996). The accidental introduction of such species to further islands is an ever-present threat. Fire is also a threat, particularly with the combination of resident people, peat soil and windy conditions on some islands (Roberts 1994). Avian malaria and avian pox have been identified in individuals on Long Island, although at present they appear restricted to this population; both could pose a major threat if the diseases spread (Hale 2008).

Conservation actions

Conservation Actions Underway
Intensive management of surviving populations has helped this species to recover and its range has increased in recent years through reintroduction. Predator and weed control and exclusion at mainland sites has helped the species, and island eradications have also been an important component in the recovery to date (Roberts 1994).  Captive populations exist.

Conservation Actions Proposed
Continue predator control at mainland sites to facilitate further introductions. Monitor potential threats including any evidence of reduced fitness as a result of low genetic diversity. Continue to survey the population size at known localities (Roberts 1994). Drain concrete-based reservoirs on Long Island and replace with alternative water source, to prevent the breeding of disease-carrying mosquitoes. Monitor the Long Island population closely to track the spread of malaria (Hale 2008). Continue to promote conservation of this species and garner public support (Roberts 1994) and further develop captive breeding programmes for future reintroduction and population supplementation efforts (Collar and Butchart 2013).

Identification

25 cm. Glossy black bird with bright chestnut saddle. Chestnut rump, tail coverts. Orange-red wattles at base of black bill. North Island subspecies; thin buff line at upper edge of saddle. Juvenile; smaller wattles. Lacks buff line. South Island subspecies; juvenile; brown with red-brown tail coverts. Voice Loud cheet, te-te-te-te.

Acknowledgements

Text account compilers
Benstead, P., Harding, M., Khwaja, N., Taylor, J., Westrip, J., Stringer, C. & Martin, R

Contributors
Stringer, C.


Recommended citation
BirdLife International (2019) Species factsheet: Philesturnus carunculatus. Downloaded from http://www.birdlife.org on 14/10/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 14/10/2019.