||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.
||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.
|Red List Category & Criteria:
||Bayliss, M., Grant, A., Maloney, R., Murray, D. & Steeves, T.
||Benstead, P., Bird, J., Butchart, S., Khwaja, N., Pilgrim, J., Symes, A., Taylor, J., Martin, R & Ashpole, J
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.
|Previously published Red List assessments:|
- 2013 – Critically Endangered (CR)
- 2012 – Critically Endangered (CR)
- 2009 – Critically Endangered (CR)
- 2008 – Critically Endangered (CR)
- 2007 – Critically Endangered (CR)
- 2006 – Critically Endangered (CR)
- 2004 – Critically Endangered (CR)
- 2000 – Critically Endangered (CR)
- 1996 – Critically Endangered (CR)
- 1994 – Critically Endangered (CR)
- 1988 – Threatened (T)
|Range Description:||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).|
|♦ Continuing decline in area of occupancy (AOO):||Unknown|
|♦ Extreme fluctuations in area of occupancy (AOO):||No||♦ Estimated extent of occurrence (EOO) - km2:||2800|
|♦ Continuing decline in extent of occurrence (EOO):||Unknown||♦ Extreme fluctuations in extent of occurrence (EOO):||No|
|♦ Number of Locations:||1||♦ Continuing decline in number of locations:||Unknown|
|♦ Extreme fluctuations in the number of locations:||No|
|Range Map:||Click here to open the map viewer and explore range.|
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).