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Charadrius obscurus 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Charadriiformes Charadriidae

Scientific Name: Charadrius obscurus Gmelin, 1789
Common Name(s):
English Southern Red-breasted Plover, New Zealand Dotterel, Southern New Zealand Dotterel
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. Volume 1: Non-passerines. Lynx Edicions BirdLife International, Barcelona, Spain and Cambridge, UK.
Taxonomic Notes: Charadrius obscurus and C. aquilonius (del Hoyo and Collar 2014) were previously lumped as C. obscurus following Sibley and Monroe (1990, 1993).
Identification information: 25 cm. Largest Charadrius plover. Sexes similar in eclipse. Brown upperparts. Feathers with paler edges. White forehead. Whitish underparts. Dark line through eye. Breeding adult, reddish underparts. Male, slightly redder on breast for much of year. Heavy black bill. Legs pale/mid grey. Iris dark brown. Voice Sharp chip most common call, long, loud churring call used in aggressive interactions.

Assessment Information [top]

Red List Category & Criteria: Critically Endangered A4a; C1+2a(ii) ver 3.1
Year Published: 2017
Date Assessed: 2017-10-01
Assessor(s): BirdLife International
Reviewer(s): Symes, A.
Contributor(s): Dowding, J., Hitchmough, R., Parrish, R. & Robertson, H.
Facilitator/Compiler(s): Benstead, P., Harding, M., Khwaja, N., Mahood, S., McClellan, R., Taylor, J., Symes, A., Stringer, C., Westrip, J., Wheatley, H.
Justification:
This species, which has been extirpated from most of its historic range, recovered from a low of just 62 birds in the early 1990s following intensive cat and rat control. However, since 2012 an extremely rapid population decline has been ongoing and the population size is once again very small. The species has therefore been uplisted to Critically Endangered.

Previously published Red List assessments:

Geographic Range [top]

Range Description:Charadrius obscurus is endemic to New Zealand. Following the split of C. aquilonius, C. obscurus is now restricted when breeding to Stewart Island, although it formerly occurred on the South Island (Dowding 1999). On Stewart Island, it declined by as much as 80% in c.40 years, numbering 62 birds (including only 18 pairs) in 1991-1992 (Dowding and Murphy 1993), but thanks to the poisoning of feral cats it recovered to 111 birds in 1997, 150 in 1999 and 250 in 2005 (J. E. Dowding in litt. 1999, Wilson 2005, Dowding 2006). Despite this management, since 2012 a rapid decline has been ongoing in the species, and the latest population estimate is only 120 birds, with potentially only 30-40 functional breeding pairs (J. Dowding in litt. 2016).

Countries occurrence:
Native:
New Zealand
Additional data:
Continuing decline in area of occupancy (AOO):Yes
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:2200
Continuing decline in extent of occurrence (EOO):YesExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:11-100Continuing decline in number of locations:Yes
Extreme fluctuations in the number of locations:No
Upper elevation limit (metres):1000
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The population reached a low of 62 birds in 1992, but following intensive management the post-breeding population has fluctuated between 240 and 290 birds since 2005 (Dowding 2013). Although management has continued, the population has declined catastrophically since 2012 for reasons that are not clear. The population is now approximately 120 individuals, with potentially no more than 30-40 pairs (60-80 mature individuals) (J. Dowding in litt. 2016).

Trend Justification:  The population has declined catastrophically since 2012 for reasons that are not clear. The recent decline has been 54% in the 4 years 2012-2016 (J. Dowding in litt. 2016), equating to an ongoing decline of c.95% decline over three generations (15 years); c.86% over two generations; and c.62% over one generation. The reason for the sudden decline since 2012 is not known.
Current Population Trend:Decreasing
Additional data:
Number of mature individuals:60-80Continuing decline of mature individuals:Yes
Extreme fluctuations:NoPopulation severely fragmented:Yes
No. of subpopulations:1Continuing decline in subpopulations:Yes
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:Yes
No. of individuals in largest subpopulation:100

Habitat and Ecology [top]

Habitat and Ecology:On Stewart Island, it breeds inland, usually at high altitudes on bare hilltops and open bog or tussock-grasslands (J. E. Dowding in litt. 1999). It lays three eggs. It feeds mostly on terrestrial and aquatic invertebrates. Young generally begin to breed in their second year. During the non-breeding season it moves to the coast where individuals feed on intertidal mudflats and beaches (Heather and Robertson 2015). The oldest recorded bird lived to at least 31 years of age (Heather and Robertson 1997).

Systems:Terrestrial; Freshwater; Marine
Continuing decline in area, extent and/or quality of habitat:Unknown
Generation Length (years):5
Movement patterns:Not a Migrant

Threats [top]

Major Threat(s): Introduced predators (primarily stoats and other mustelids) were the primary cause of extinction on the South Island (Dowding 1999). Feral cats (and possibly rats) caused the rapid decline on Stewart Island (Dowding and Murphy 1993). Males in particular were badly affected as they incubate at night and are more vulnerable to nocturnal predators, and this led to a severe gender bias in the early 1990s, with female-female pairs forming (Dowding 2013). With the current decline it again appears that the gender bias may have re-established (J. Dowding in litt. 2016). Where native avian predators (notably Kelp Gull Larus dominicanus) occur at high densities, they are a significant threat to eggs and chicks. The cause of the sudden, rapid decline since 2012 is currently not known, though the very high rate of the decline suggests that it is probably being driven by the loss of adult birds, rather than as a result of breeding failure (J. Dowding in litt. 2016).

Conservation Actions [top]

Conservation Actions: Conservation and research actions underway
On Stewart Island, cats and rodents are intensively controlled at four important breeding sites (J. E. Dowding in litt. 1999, Ombler 2006). Captive-breeding trials with aquilonius have been undertaken in case the technique is required for obscurus (Dowding 1998). Chicks have been raised successfully (J. Dowding in litt. 1999), but their survival in the wild has been low. A revised species recovery plan was published in 2007 (Dowding and Davis 2007), but this has now expired (J. Dowding in litt. 2016). During the 2016/17 season, cat and rat control is being intensified in the main breeding area around Table Hill in an attempt to halt the current decline. In the Conservation Status of New Zealand Birds (Robertson et al. 2017) this species is still lumped with C. aquilonius, but each subspecies is assessed separately. Robertson et al. (2017) assess C. obscurus obscurus as Nationally Critical.

Conservation and research actions proposed
There is an urgent need to identify the driver of the current decline and modify management as necessary (J. Dowding in litt. 2016). Estimate the population size annually, and continue current management on Stewart Island. Maintain the mustelid-free status of Stewart Island.

Citation: BirdLife International. 2017. Charadrius obscurus. The IUCN Red List of Threatened Species 2017: e.T62290750A119149766. . Downloaded on 22 July 2018.
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