Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Charadriiformes Charadriidae

Scientific Name: Anarhynchus frontalis
Species Authority: Quoy & Gaimard, 1830
Common Name(s):
English Wrybill
Taxonomic Source(s): del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Lynx Edicions BirdLife International.
Identification information: 20 cm. Stocky, pale grey plover, tip of black bill turned to right. Ash-grey crown, nape, upperparts. White underparts. Black band across upper chest thick in breeding male, thinner in breeding female, sometimes absent in non-breeding birds. Black frontal band above white forehead in male, absent in female. Juvenile breast-band absent, back feathers tinged with white. Voice Short, clear weet.

Assessment Information [top]

Red List Category & Criteria: Vulnerable C2a(i) ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Dowding, J., Grant, A., Melville, D. & Riegen, A.
Facilitator/Compiler(s): Benstead, P., Khwaja, N., Mahood, S., McClellan, R., Pilgrim, J., Taylor, J.
This species is listed as Vulnerable because it has a small population, which is undergoing a continuing decline owing to habitat degradation and the impacts of introduced predators.

Previously published Red List assessments:
2008 Vulnerable (VU)
2006 Vulnerable (VU)
2004 Vulnerable (VU)
2000 Vulnerable (VU)
1996 Vulnerable (VU)
1994 Vulnerable (VU)
1988 Lower Risk/least concern (LR/lc)

Geographic Range [top]

Range Description: Anarhynchus frontalis breeds in Canterbury and Otago, South Island, New Zealand. It is found on over 26 riverbeds, but is only common on 10. It winters mainly north of 38°S in the North Island. In the last 40 years, population counts have varied between 3,000 and 5,000 individuals (Sagar et al. 1999a), probably reflecting the difficulty in surveying the species (J. E. Dowding in litt. 1999), but the current best estimate is 4,500-5,000 birds (Riegen and Dowding 2003). Analysis of wintering flocks indicates a slow decline over the last 40 years (Veitch and Habraken 1999), which is supported by preliminary results from a long-term demographic study (J. E. Dowding in litt. 1999).

Countries occurrence:
New Zealand
Continuing decline in area of occupancy (AOO): Yes
Extreme fluctuations in area of occupancy (AOO): No
Estimated extent of occurrence (EOO) - km2: 7700
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: Yes
Extreme fluctuations in the number of locations: No
Upper elevation limit (metres): 600
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: The population is estimated to number 4,500-5,000 individuals, roughly equating to 3,000-3,300 mature individuals.

Trend Justification:  Analysis of wintering flocks indicates a slow decline over the last 40 years (Veitch and Habraken 1999), which is supported by preliminary results from a long-term demographic study (J. E. Dowding in litt. 1999).
Current Population Trend: Decreasing
Additional data:
Number of mature individuals: 3000-3300 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
No. of individuals in largest subpopulation: 1-89

Habitat and Ecology [top]

Habitat and Ecology: It breeds on braided riverbeds, and frequents sheltered estuaries and coasts over the non-breeding season. Nests are built within 250 m of running water, and are usually hollows in bare shingle, lined with more than 100 small pebbles (Marchant and Higgins 1993, J. E. Dowding in litt. 1999). It lays two eggs. Young usually begin to breed at two or three years of age (Marchant and Higgins 1993). Mark-recapture of almost 2,400 birds indicates that many live past 10 years of age (Davies 1997), the average adult life expectancy is c.5.4 years (Hay 1984). Diet comprises mostly mayflies and caddisflies, but is more general when rivers are in flood (Heather and Robertson 1997).

Systems: Freshwater; Marine
Continuing decline in area, extent and/or quality of habitat: Yes
Generation Length (years): 7.6
Movement patterns: Full Migrant
Congregatory: Congregatory (and dispersive)

Threats [top]

Major Threat(s): Breeding habitat is deteriorating, primarily from the encroachment of weeds as hydroelectric schemes reduce seasonal flushing of riverbeds (Marchant and Higgins 1993), and perhaps also owing to changes in the management of gravel extraction regimes (D. Melville in litt. 2012). Land intensification in the high country will have similar effects on reducing water flow, as well as increasing the concentration of nutrients in rivers, further encouraging weed growth (Rebergen 2011). The extent of predation by stoats Mustela erminea and cats has not been quantified, but is likely to be substantial, perhaps especially in the non-breeding season (Battley and Moore 2004). The recent illegal introduction of rabbit haemorrhagic disease has resulted in the localised switching of some predators to a diet containing proportionately more birds. Predation by Kelp Gulls Larus dominicanus may pose an increasing threat as they become more numerous in association with human activities (J. E. Dowding in litt. 1999). Increasing use of riverbeds for recreational purposes and floods are also threats (Marchant and Higgins 1993, A. Grant in litt. 1999). Water quality deterioration and disturbance pose threats at the species's wintering grounds in Auckland and Northland (Rebergen 2011). Further threats may include the conversion of coastal habitat for aquaculture, development of wind farms, and the spread of mangroves (D. Melville in litt. 2012).

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
The species was shot for sport until 1940, when it became fully protected (Marchant and Higgins 1993). Research on the impact of predation and prey-switching is being undertaken. Predator control for Black Stilt Himantopus novaezelandiae protection benefits a small proportion of the population (J. E. Dowding in litt. 1999). Project River Recovery carries out habitat restoration and predator research in the McKenzie basin (A. Grant in litt. 1999).

Conservation Actions Proposed
Model demographic data to determine population trends (J. E. Dowding in litt. 1999). Continue to monitor wintering aggregations. Control introduced predators and invasive plants at important sites. Control the recreational use of riverbeds, perhaps by delimiting areas where humans are excluded. Identify and monitor key areas of habitat (Rebergen 2011). Increase awareness of river-dwelling birds as part of the current government policy formulation on freshwater resource management (D. Melville in litt. 2012).

Citation: BirdLife International. 2012. Anarhynchus frontalis. The IUCN Red List of Threatened Species 2012: e.T22693928A38790089. . Downloaded on 10 October 2015.
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