Xenicus gilviventris 


Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Passeriformes Acanthisittidae

Scientific Name: Xenicus gilviventris
Species Authority: Pelzeln, 1867
Common Name(s):
English South Island Wren, South Island Rock Wren, Rock Wren, New Zealand Rockwren
Taxonomic Source(s): Turbott, E.G. 1990. Checklist of the birds of New Zealand. Ornithological Society of New Zealand, Wellington.
Taxonomic Notes: "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 information: 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.

Assessment Information [top]

Red List Category & Criteria: Vulnerable C1+2a(i) ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Gaze, P., Hay, R. & Hitchmough, R.
Facilitator/Compiler(s): Benstead, P., Harding, M., Khwaja, N., Mahood, S., McClellan, R. & Taylor, J.
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.

Previously published Red List assessments:
2008 Vulnerable (VU)
2005 Vulnerable (VU)
2004 Near Threatened (NT)
2000 Lower Risk/near threatened (LR/nt)
1994 Lower Risk/near threatened (LR/nt)
1988 Lower Risk/least concern (LR/lc)

Geographic Range [top]

Range Description: 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).

Countries occurrence:
New Zealand
Continuing decline in area of occupancy (AOO): Unknown
Extreme fluctuations in area of occupancy (AOO): No
Estimated extent of occurrence (EOO) - km2: 11200
Continuing decline in extent of occurrence (EOO): Unknown
Extreme fluctuations in extent of occurrence (EOO): No
Number of Locations: 11-100
Continuing decline in number of locations: Unknown
Extreme fluctuations in the number of locations: No
Lower elevation limit (metres): 1200
Upper elevation limit (metres): 2400
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: 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).
Current Population Trend: Decreasing
Additional data:
Number of mature individuals: 2500-9999 Continuing decline of mature individuals: Yes
Extreme fluctuations: No Population severely fragmented: No
No. of subpopulations: 2-100 Continuing decline in subpopulations: Unknown
Extreme fluctuations in subpopulations: No All individuals in one subpopulation: No

Habitat and Ecology [top]

Habitat and 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).

Systems: Terrestrial; Freshwater
Continuing decline in area, extent and/or quality of habitat: Unknown
Generation Length (years): 3.5
Movement patterns: Not a Migrant

Threats [top]

Major Threat(s): 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 [top]

Conservation Actions: 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.

Citation: BirdLife International. 2012. Xenicus gilviventris. The IUCN Red List of Threatened Species 2012: e.T22698585A38604942. . Downloaded on 26 November 2015.
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