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.

Family/Sub-family Acanthisittidae

Species name author Pelzeln, 1867

Taxonomic source(s) Sibley and Monroe (1990, 1993), Turbott (1990)

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.

Population estimate

Population trend

Range estimate (breeding/resident)

Country endemic?

2,500-9,999

decreasing

11,100 km²

Yes

Range & 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 Fiordland². It was described as locally common², 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 years³. Its population is estimated to number fewer than 10,000 individuals⁴. Its range continues to decline⁸ and a 40% decline in abundance over a 20 year period occurred in the Murchison mountains⁷.

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 vegetation⁵. Flight is relatively weak, although birds still range over extensive areas of steep mountain terrain¹.

Threats The major threat to this species is predation by introduced mammals, house mouse Mus musculus and stoat Mustela erminea, particularly in years when M. erminea populations are high in response to mouse plagues¹. The only study on nesting in this species showed significant levels of egg and chick loss to mice and stoat⁶.

Conservation measures 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 followed⁹ and a translocation to Secretary Island is planned for 2008.

Conservation measures 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 1. R. Hay in litt. (1999). 2. Heather and Robertson (1997). 3. P. Gaze per R. Hitchmough in litt. (2005). 4. R. Hitchmough in litt. (2005). 5. Higgins et al. (2001). 6. Michelsen-Heath (1989). 7. Willians (2007). 8. Michelsen-Heath and Gaze (in press). 9. Weston (2006).

Text account compilers Phil Benstead (BirdLife International), Matt Harding (BirdLife International), Simon Mahood (BirdLife International), Rachel McClellan (BirdLife International)

Contributors Peter Gaze, R. Hay, Rod Hitchmough (Department of Conservation)

IUCN Red List evaluators Stuart Butchart (BirdLife International), Simon Mahood (BirdLife International)

Recommended citation BirdLife International (2009) Species factsheet: Xenicus gilviventris. Downloaded from http://www.birdlife.org on 10/2/2010

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.

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