email a friend
printable version
CR
Black Stilt Himantopus novaezelandiae
BirdLife Species Champion Become a BirdLife Preventing Extinctions Programme Supporter
For information about BirdLife Species Champions and Species Guardians visit the BirdLife Preventing Extinctions Programme.

Justification
Despite 20 years of intensive conservation efforts, this species remains one of the most threatened shorebirds in the world. It is classified as Critically Endangered because, although it has increased over the last decade, it still has only a tiny population. The annual release of substantial numbers of captive-reared birds, in combination with predator control, has almost certainly prevented it from becoming Extinct in the Wild, and the species's long-term survival remains dependent upon this intensive conservation management.

Taxonomic source(s)
del Hoyo, J.; Collar, N. J.; Christie, D. A.; Elliott, A.; Fishpool, L. D. C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Barcelona, Spain and Cambridge UK: Lynx Edicions and BirdLife International.
Turbott, E. G. 1990. Checklist of the birds of New Zealand. Ornithological Society of New Zealand, Wellington.

Identification
40 cm. Black, long-legged stilt. Adult, black with long, fine, black bill. Very long red legs. Juvenile, white breast, neck, head. Black patch around eyes. Similar spp. Hybridises with Pied Stilt H. himantopus. Resulting individuals highly variable. Compared to pure adults, darker hybrid adults have longer bills, shorter legs. Compared to pure juveniles, hybrid adults have some solid black on breast. Voice Loud, high-pitched, monotonous yapping.

Distribution and population
Himantopus novaezelandiae was formerly widespread, breeding and wintering across the North and South Islands of New Zealand, but following a long-term decline it is now restricted during the breeding season to the upper Waitaki Valley in the South Island. Approximately 90% of the population is sedentary, but small numbers still overwinter in the North Island. The population may have numbered 500-1,000 birds in the 1940s (Pierce 1984), by which time it had ceased to breed in the North Island and was rare as a breeding species in the lowlands. It continued to decline to a low of just 23 birds in 1981, when intensive management began (Keedwell 2005). In 2001, the wild breeding population consisted of just seven pairs (Keedwell et al. 2002), but a maximum of 84 adults were recorded in the wild in August 2002 (M. Bayliss in litt. 2002). By the 2004-2005 breeding season, there were 11 productive pairs (R. Maloney in litt. 2005). Since this point the population has increased primarily thanks to the annual release of 'fast-tracked' captive-reared subadults and juveniles - 77 and 16 respectively in 2007-2008, more than 80 in 2009 and a further 70 in 2012 near Lake Tekapo (R. Maloney in litt. 2008, Anon. 2012). During 2007-2008 there were a total of 20 breeding pairs and 78 mature individuals in the wild (although it is not clear how many of these are of captive origin and have not yet bred in the wild) (R. Maloney in litt. 2008). In 2012, before the annual release of captive reared birds, the free-living population was around 130 individuals (Anon. 2012). The species's survival remains dependent on captive-rearing efforts until predator-free breeding habitat can be maintained (Keedwell 2005). Fewer than 20 dark H. novaezelandiae x H. leucocephalus hybrids are currently known (R. Maloney in litt. 2008). Cryptic hybrids are extremely rare (Steeves et al. 2010).

Population justification
The estimate of 40 individuals (roughly equivalent to 27 mature individuals) is based on 20 productive breeding pairs at end of 2007-2008 season; a total of 78 'mature individuals' were counted in 2008 (R. Maloney in litt. 2008), but it is unclear how many of these were captive bred and have not yet bred in the wild successfully.

Trend justification
The number of productive breeding pairs roughly doubled during 1995-2005, to 17 breeding pairs in the wild, with a further increase to 20 productive pairs in 2007-2008, but these figures conceal a fair amount of fluctuation. Furthermore, the apparent increase is largely thanks to the annual release of captive-bred subadults and juveniles (93 birds in 2007-2008; R. Maloney in litt. 2008).

Ecology
It breeds on braided riverbeds, but also occurs in wetlands and swamplands, and some of the population winters along the coastline in inter-tidal habitats. It feeds primarily on insects, but also takes molluscs (Anon. 2009) and small fish (Pierce 1986a). The species is monogamous and birds pair for life (Anon. 2009). It lays four eggs and will usually re-nest if the first clutch is lost early in the season. Both birds in a pair share incubation duties (Anon. 2009). Most breed for the first time at three years of age. The average age is 6.8 years, and there are two birds that are older than 10 years.

Threats
Predators, in particular introduced mammals such as cats, ferrets Mustela furo, stoats M. erminea, hedgehogs Erinaceus sp. and brown rats Rattus norvegicus, and the native Australasian Harrier Circus approximans and Kelp Gull Larus dominicanus (Pierce 1986b, D. P. Murray per A. Grant in litt. 1999) are today the primary threat, but the combined impact of habitat loss has exacerbated declines. Habitat has been lost through conversion to agriculture and hydroelectric developments (Anon. 2009). Nests are destroyed, and predation is potentially increased, by drainage and hydroelectric development, weed growth and flood-control programmes (Dowding and Murphy in press), and nesting birds are disturbed by recreational use of riverbeds. Adverse weather and natural flooding are additional, unpredictable threats (D. P. Murray per A. Grant in litt. 1999).

Hybridisation with H. leucocephalus, which was allowed to continue under former management strategies, posed a threat because the crash in the Black Stilt population made it difficult for them to form conspecific pairs and a biased sex ratio resulted in single males mating with H. leucocephalus females or hybrids (Pierce 1984, R. Maloney in litt. 1999, Steeves et al. 2010), although hybridisation has been bidirectional (Steeves et al. 2010). Extensive bidirectional hybridisation appears to have been taking place since at least 1960 (Steeves et al. 2010). The sex ratio is now even and the frequency of hybridisation has decreased (R. Maloney in litt. 2008, Steeves et al. 2010). Adjustment of the sex ratio, low reproductive success in hybrid females and high mortality are the likely reasons for a lack of widespread introgression between the two species (Steeves et al. 2010). Adult mortality in the wild remains very high (Keedwell 2005). Despite the genetic bottleneck experienced by H. novaezelandiae, there is so far no evidence of inbreeding depression in the wild (Steeves et al. 2010). However, a negative relationship has been shown between inbreeding and fitness in the captive population; in light of this care should be taken to minimise the relatedness of pairs forming in captivity (Hagen et al. 2011).


Conservation Actions Underway
Recent advances in release methods appear to have enhanced the initial survival of released birds from 20-45% to 80-100%, but require further testing (Chambers and MacAvoy 1999). Active management involves double and triple clutching of parents by removing eggs to encourage re-laying. The removed eggs are reared in captivity. Playback calls are broadcast to juvenile birds during captive-rearing to equip them with the behavioural and auditory recognition skills necessary for survival (Galbraith et al. 2007). A study was recently published on the influence of release age, size of release group and size of the wild population at release sites on the post-release movements of captive-reared Black Stilts, with implications for the future management of the programme (van Heezik et al. 2009). Predator exclusion fencing was first installed at the site near Lake Tekapo in the late 1970s (Anon. 2009). Trapping for predators around all wild nests has been on-going since 1997 (R. Maloney in litt. 1999), and research is underway to determine the nature of the threat from each predator species (D. P. Murray per A. Grant in litt. 1999). Hybrids, now numbering fewer than 20 within the Black Stilt's range, are controlled (R. Maloney in litt. 2008). Water-levels are manipulated in managed wetlands to attract birds to feed, and possibly breed, in areas where predators are controlled (Dowding and Murphy in press). Habitat restoration is on-going, and involves the removal of exotic weeds from riverbeds (Heather and Robertson 1997). The introduction of a second population on a suitable predator-free island is desirable and has undergone a feasibility study (Murray and Sanders 2000, R. Maloney in litt. 2008), but it is unlikely that a suitable release site will be found. The species's recovery plan reportedly aims to increase the population to at least 250 breeding birds by 2011 (Anon. 2009). Conservation Actions Proposed
Continue to monitor population trends. Monitor rates of habitat loss and degradation throughout the species's range. Maintain and improve productivity of the captive population, and ensure pairs forming in captivity are sufficiently unrelated to prevent potential inbreeding depression (Hagen et al. 2011). Establish a self-sustaining population on a predator-free island. Encourage public interest and support (Reed and Murray 1993). Seek to maintain predator-free habitat for breeding within its current range. Continue efforts to prevent hybridisation with H. himantopus, and maintain parity in the adult sex ratio in order to avoid conditions under which introgression with H. himantopus could occur (Steeves et al. 2010).


Related state of the world's birds case studies

References
Anon. 2012. 45 black stilt released to boost wild population of just 130 birds. Wildlife Extra News. Available at: http://www.wildlifeextra.com/go/news/black-stilt012.html#cr. (Accessed: 11/10/2013).

Chambers, G. K.; MacAvoy, E. S. 1999. Molecular genetic analysis of hybridisation. Department of Conservation, Wellington.

Dowding, J.E. and 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.

Galbraith, J. A.; Sancha, S. E.; Maloney, R. F.; Hauber, M. E. 2007. Alarm responses are maintained during captive rearing in chicks of endangered Kaki. Animal Conservation 10(1): 103-109.

Hagen, E. N.; Hale, M. L.; Maloney, R. F.; Steevs, T. E. 2011. Conservation genetic management of a Critically Endangered New Zealand endemic bird: minimizing inbreeding in the Black Stilt Himantopus novaezelandiaeIbis 153: 556-561.

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

Keedwell, R. 2005. Black Stilt (Kaki) recovery effort. Wingspan 15: 15.

Keedwell, R. J.; Maloney, R. F.; Murray, D. P. 2002. Predator control for protecting kaki (Himantopus novaezelandiae) - lessons from 20 years of management. Biological Conservation 105: 369-374.

Murray, D. P.; Sanders, M. D. 2000. Assessment of Chatham island as a location for liberation of Black Stilts.

Pierce, R. 1986. Black Stilt. John McIndoe, Dunedin.

Pierce, R. J. 1984. The changed distribution of stilts in New Zealand. Notornis 31: 7-18.

Pierce, R. J. 1986. Differences in susceptibility to predation during nesting between Pied and Black Stilts Himantopus spp. The Auk 103: 273-280.

Reed, C. E. M.; Murray, D. P.; Butler, D. J. 1993. Black Stilt recovery plan (Himantopus novaezealandiae). Department of Conservation, Wellington.

Steeves, T. E.; Maloney, R. F.; Hale, M. L.; Tylianakis, J. M.; Gemmell, N. J. 2010. Genetic analyses reveal hybridization but no hybrid swarm in one of the world’s rarest birds. Molecular Ecology 19(23): 5090-5100.

Wallis, G. 1999. Genetic status of New Zealand Black Stilt Himantopus novaezelandiae and the impact of hybridisation.

Further web sources of information
Alliance for Zero Extinction (AZE) species/site profile. This species has been identified as an AZE trigger due to its IUCN Red List status and limited range.

Click here for more information about the Alliance for Zero Extinction (AZE)

Explore HBW Alive for further information on this species

New Zealand Govt - Dept of Conservation - Recovery Plan

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

Text account compilers
Benstead, P., Bird, J., Butchart, S., Khwaja, N., Pilgrim, J., Symes, A., Taylor, J., Martin, R

Contributors
Bayliss, M., Grant, A., Maloney, R., Murray, D., Steeves, T.

Recommended citation
BirdLife International (2014) Species factsheet: Himantopus novaezelandiae. Downloaded from http://www.birdlife.org on 21/08/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 21/08/2014.

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

ARKive species - New Zealand black stilt (Himantopus novaezelandiae) 0

Key facts
Current IUCN Red List category Critically Endangered
Family Recurvirostridae (Avocets, Stilts)
Species name author Gould, 1841
Population size 27 mature individuals
Population trend Increasing
Distribution size (breeding/resident) 2,800 km2
Country endemic? Yes
Links to further information
- Additional Information on this species