Species

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Justification
This species has a very small, severely fragmented population and a small overall range. Extirpation of the southern subspecies has been averted owing to extensive predator control, and numbers are now gradually increasing. However, the status of the northern subspecies is uncertain and populations in some areas have undergone substantial declines. The species is therefore listed as Endangered. Further clarification of the status of the northern subspecies may lead to downlisting in the future.

Taxonomic source(s)
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.
Turbott, E. G. 1990. Checklist of the birds of New Zealand. Ornithological Society of New Zealand, Wellington.

Identification
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.

Distribution and population
Charadrius obscurus is endemic to New Zealand. Subspecies obscurus is now restricted when breeding to Stewart Island, but 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). Subspecies aquilonius breeds in northern North Island. The population was estimated at 1,313 birds in 1989, 1,452 in 1996 and 1,701 in 2004. The current population status is management-dependent, and significant declines would begin immediately if intensive management stopped (R. Hitchmough in litt. 2005). Management at some sites is funded by programmes for other species, and there is no guarantee that the current level of management will continue. The east coast of the North Island holds 83% of the northern subspecies's population including all managed subpopulations. It has been declining rapidly at Wiakato and elsewhere along the west coast and local extinction and a consequent reduction in its range size are likely.

Population justification
The latest estimate for subspecies aquilonius was that its population numbered 1,701 in October 2004. The latest for subspecies obscurus was that its population numbered 270, in April 2006 (J. E. Dowding in litt. 2008). This totals c.2,000 individuals, equating to c.1,300 mature individuals. Within the northern subspecies, if subpopulations are found to contribute to larger metapopulations (in excess of 250 individuals) with gene flow between them, then the species will warrant downlisting.

Trend justification
Overall, the species's population size is now increasing owing to intensive management. However, continuing declines in the past were significant and unmanaged populations continue to decline towards extinction, hence its range is contracting. The suspected trend over the last ten years is of a decline, although the rate has not been estimated.

Ecology
On the North Island, it usually breeds on wide ocean beaches, estuaries and harbours with tidal mudflats (Heather and Robertson 1997). 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. The oldest recorded bird lived to at least 31 years of age (Heather and Robertson 1997).

Threats
Introduced predators were the primary cause of extinction on the South Island (Dowding 1999). They remain the greatest threat on the North Island - one study indicated that at unmanaged sites 60% of nests were lost to predators (Dowding 1998). Feral cats caused the rapid decline on Stewart Island (Dowding and Murphy 1993). On the North Island, housing developments and encroachment by dune-stabilising weeds reduce habitat, and disturbance by livestock, humans, dogs and vehicles reduces breeding success (Dowding 1993, Lord et al. 2001). A known breeding site has been bulldozed as part of an attempted storm protection programme (Anon. 2008). Storms and very high tides can cause nest failures (J. E. Dowding in litt. 1999, Wills et al. 2003). Where native avian predators (notably Kelp Gull Larus dominicanus) occur at high densities, they are a significant threat to eggs and chicks.

Conservation actions underway
On the North Island, management at important breeding sites includes predator trapping, gull control, advocacy, reduction of nest losses to flooding, and the presence of wardens (Dowding and Davis 2007). This results in local improvements in breeding success - 20% of c.600 breeding pairs were managed in 1998-1999 (Dowding and Murphy 2001). In some areas, there is substantial community involvement in management (Dowding 2006). 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. E. 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).

Conservation actions proposed
Complete a full North Island census every seven years. Continue existing protection programmes on North Island. Expand protection to new sites on North Island, with priorities being on the west coast and in the Far North. Increase community involvement and other-agency partnerships in management activities on North Island. Identify and protect important breeding, roosting and flocking habitat on North Island by advocacy and statutory protection. Estimate the population size annually on Stewart Island. Continue current management on Stewart Island. Maintain the mustelid-free status of Stewart Island. Investigate more cost-effective methods of cat control on Stewart Island.

References
Dowding, J. E.; Murphy, E. C. 1993. Decline of the Stewart Island population of the New Zealand Dotterel. Notornis 40: 1-14.

Dowding, J. 1993. New Zealand Dotterel recovery plan. Department of Conservation, Wellington.

Heather, B. D.; Robertson, H. A. 1997. The field guide to the birds of New Zealand. Oxford University Press, Oxford, UK.

Dowding, J. E. 1998. The impact of predation on New Zealand Dotterels.

Dowding, J. E. 1999. Past distribution and decline of the New Zealand Dotterel (Charadrius obscurus) in the South Island of New Zealand. Notornis 46: 167-180.

Lord, A.; Waas, J. R.; Innes, J.; Whittingham, M. J. 2001. Effects of human approaches to nests of northern New Zealand Dotterels. Biological Conservation 98: 233-240.

Dowding, J. E.; Murphy, E. C. 2001. The impact of predation by introduced mammals on endemic shorebirds in New Zealand: a conservation perspective. Biological Conservation 99: 47-64.

Wills, D. E.; Murray, J.; Powlesland, R. G. 2003. Impact of management on the breeding success of the northern New Zealand dotterel (Charadrius obscurus aquilonius) on Matakana Island, Bay of Plenty. Notornis 50: 1-10.

Ombler, K. 2006. Breeding success for southern dotterels. Forest and Bird: 12.

Dowding, J. E.; Davis, A. M. 2007. New Zealand Dotterel (Charadrius obscurus) recovery plan, 2004-2014. Department of Conservation, Wellington.

Dowding, J.E. 2006. Management of northern New Zealand dotterels on Coromandel Peninsula. Department of Conservation, Wellington.

Anon. 2008. Matapouri sandspit bulldozed. Forest and Bird: 8.

Further web sources of information
New Zealand Govt - Dept of Conservation - Recovery Plan

View photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Benstead, P., Harding, M., Khwaja, N., Mahood, S., McClellan, R., Taylor, J.

Contributors
Dowding, J., Hitchmough, R., Parrish, R.

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2013) Species factsheet: Charadrius obscurus. Downloaded from http://www.birdlife.org on 19/06/2013. Recommended citation for factsheets for more than one species: BirdLife International (2013) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 19/06/2013.

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.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Additional resources for this species

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