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South Island Wren Xenicus gilviventris

Justification
This species has a small and fragmented population which is estimated to be undergoing a decline owing to heavy nest predation. It is therefore considered Vulnerable.

Taxonomic source(s)
Turbott, E. G. 1990. Checklist of the birds of New Zealand. Ornithological Society of New Zealand, Wellington.

Taxonomic note
'South Island Wren' is used as the common name following Sibley and Monroe (1990, 1993) as the name 'Rock Wren' as used in BirdLife International (2000, 2004) is taken by Salpinctes obsoletus.

Identification
10 cm. Small alpine bird. Male dull green above, grey-brown below, yellow flanks; female more olive brown; long legs and fine black bill. Similar: None in range. Hints: Has unusual habit of vigorously bobbing up and down. Voice: Three notes, first accentuated.

Distribution and population
Xenicus gilviventris is endemic to New Zealand. Once found in the North Island prior to European settlement, it is now restricted to the South Island, where it ranges from north-west Nelson, down through Westland and the Southern Alps, to Fiordland (Heather and Robertson 1997). It was described as locally common (Heather and Robertson 1997), but its distribution is fragmented, and a recent analysis of sightings indicates that about 20% of known localities have had no sightings in the past 20 years (P. Gaze per R. Hitchmough in litt. 2005). Its population is estimated to number fewer than 10,000 individuals (R. Hitchmough in litt. 2005). Its range continues to decline (Michelsen-Heath and Gaze in press) and a 40% decline in abundance over a 20-year period occurred in the Murchison mountains (Willians 2007).

Population justification
The population is estimated to number 2,500-9,999 mature individuals. This equates to 3,750-14,999 individuals, rounded here to 3,500-15,000 individuals (R. Hitchmough in litt. 2005).

Trend justification
In 2005, 20% of known localities had had no sightings in the past 20 years (P. Gaze per R. Hitchmough in litt. 2005).

Ecology
Populations are confined to alpine and subalpine habitat, on mountain ranges and in valleys above the timberline, between c.920 m and 2,900 m (mostly 1,200 to 2,400 m). It inhabits rocky slopes, including talus, open scree, glacial moraine and rocky outcrops, usually vegetated with alpine and subalpine low shrublands. It nests among loose rock or debris, on bluffs or rocky ledges, always close to vegetation. It is insectivorous, but will occasionally take fruits and seeds from alpine vegetation (Higgins et al. 2001). Flight is relatively weak, although birds still range over extensive areas of steep mountain terrain (R. Hay in litt. 1999).

Threats
The major threat to this species is predation by introduced mammals, house mice Mus musculus and stoats Mustela erminea, particularly in years when M. erminea populations are high in response to mouse plagues (R. Hay in litt. 1999). The only study on nesting in this species showed significant levels of egg and chick loss to mice and stoat (Michelsen-Heath 1989).

Conservation Actions Underway
In January 2005, the Department of Conservation relocated 24 individuals from the Murchison Mountains to predator-free Anchor Island in Dusky Sound. Monitoring of this translocated population has followed (Weston 2006), and a translocation to Secretary Island was planned for 2008. Conservation Actions Proposed
Survey to verify population estimates and identify key sites for this species. Carry out predator control programmes at key breeding sites, especially during plague years. Continue the programme of translocation, including considering translocations to Secretary Island in Doubtful Sound.

References
BirdLife International. 2000. Threatened birds of the world. Lynx Edicions and BirdLife International, Barcelona and Cambridge.

BirdLife International. 2004. Threatened birds of the world 2004. CD-Rom.

Heather, B. D.; Robertson, H. A. 1997. The field guide to the birds of New Zealand. Oxford University Press, Oxford, UK.

Higgins, P. J.; Peter, J. M.; Steele, W. K. 2001. Handbook of Australian, New Zealand and Antarctic Birds: Tyrant-flycatchers to Chats. Oxford University Press, Oxford.

Michelsen-Heath, S. 1989. The breeding biology of the Rock Wren, Xenicus gilviventris, in the Murchison Mountains, Fjordland National Park, South Island, New Zealand. Thesis. MSc, University of Otago, Dunedin.

Michelsen-Heath, S.; Gaze, P. 2007. Changes in abundance and distribution of the Rock Wren (Xenicus gilviventris) in the South Island, New Zealand. Notornis 54(2): 71-78.

Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.

Sibley, C. G.; Monroe, B. L. 1993. A supplement to 'Distribution and taxonomy of birds of the world'. Yale University Press, New Haven, USA.

Weston, K. 2006. Post-translocation monitoring of Rock Wren (Xenicus gilviventris) on Anchor Island.

Further web sources of information
Explore HBW Alive for further information on this species

Search for photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Benstead, P., Harding, M., Khwaja, N., Mahood, S., McClellan, R., Taylor, J.

Contributors
Gaze, P., Hay, R., Hitchmough, R.

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2016) Species factsheet: Xenicus gilviventris. Downloaded from http://www.birdlife.org on 26/05/2016. Recommended citation for factsheets for more than one species: BirdLife International (2016) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 26/05/2016.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Additional resources for this species

ARKive species - South Island wren (Xenicus gilviventris) 0

Key facts
Current IUCN Red List category Vulnerable
Family Acanthisittidae (New Zealand wrens)
Species name author Pelzeln, 1867
Population size 2500-9999 mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 11,200 km2
Country endemic? Yes
Links to further information
- Additional Information on this species