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Xenicus gilviventris 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Passeriformes Acanthisittidae

Scientific Name: Xenicus gilviventris
Species Authority: Pelzeln, 1867
Common Name(s):
English New Zealand Rockwren, South Island Rock Wren, Rock Wren, South Island Wren
Taxonomic Source(s): del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A., Fishpool, L.D.C., Boesman, P. and Kirwan, G.M. 2016. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 2: Passerines. Lynx Edicions and BirdLife International, Barcelona, Spain and Cambridge, UK.
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: Endangered A3ce+4ce ver 3.1
Year Published: 2016
Date Assessed: 2016-10-01
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., Stringer, C., Westrip, J.
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.

Previously published Red List assessments:

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:
Native:
New Zealand
Additional data:
Continuing decline in area of occupancy (AOO):Unknown
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:78600
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:11-100Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:NoLower 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:5000Continuing decline of mature individuals:Yes
Extreme fluctuations:NoPopulation severely fragmented:Yes
No. of subpopulations:2-100Continuing decline in subpopulations:Yes
Extreme fluctuations in subpopulations:NoAll 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. It is likely that predation rates vary significantly from year to year (Gaze 2013), and predation may be particularly high 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). A number of recent unpublished studies led by the New Zealand Department of Conservation have observed extremely high (80-100%) nest failure due to predation (DOC, unpublished data per Weston 2014, Webb 2015). High rates of predation within isolated populations may be contributing to their demographic instability (Weston 2014). There is an additional threat to this species from climate change, especially if warming temperatures make its core habitat more suitable for ship rats – a potential nest predator which is currently absent (Gaze 2013).

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. 2016. Xenicus gilviventris. The IUCN Red List of Threatened Species 2016: e.T22698585A93691022. . Downloaded on 11 December 2016.
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