||Himantopus novaezelandiae Gould, 1841
||Turbott, E.G. 1990. Checklist of the Birds of New Zealand. Ornithological Society of New Zealand, Wellington.
||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:
||Butchart, S. & Symes, A.
||Bayliss, M., Grant, A., Maloney, R., Murray, D., Steeves, T. & Cleland, S.
||Benstead, P., Bird, J., Butchart, S., Khwaja, N., Pilgrim, J., Symes, A., Taylor, J., Martin, R, Ashpole, J & Stringer, C.
Despite 35 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:|
- 2015 – Critically Endangered (CR)
- 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. The population is sedentary, with small numbers of birds being sighted in other New Zealand regions. 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 1999-2000, the wild breeding population consisted of just four pairs (Keedwell et al. 2002), and a maximum of 31 adults. Since this point the population has increased primarily thanks to the annual release of 80-120 'fast-tracked' captive-reared subadults and juveniles.). In the last 15 years pair numbers have fluctuated between 8 and 23 pairs, and the total adult wild population between 39 and 93 birds. Except for one wild hatched bird, all of the adult population has been captive reared and released from either wild laid or captive laid eggs. The February 2016 population of 93 adults is the highest ever recorded since management begun. Recruitment rates from releases of juveniles or sub-adults remains very low (22-25%), and techniques for managing predators in the wild are not yet operational at the large scales needed to encompass kaki home ranges. Therefore, the species's survival remains dependent on captive-rearing efforts until predator-free breeding habitat can be maintained (Keedwell 2005). Hybridisation with H. leucocephalus was exacerbated during periods of cross-fostering of kaki eggs to pied stilt parents in the 1980’s and because low population size and the widely dispersed kaki population meant that some kaki were unable to find other kaki mates. Fewer than 5 dark H. novaezelandiae x H. leucocephalus hybrids are currently known (R. Maloney in litt. 2016), and through continued positive assortative mating, almost all kaki are pure bred. Cryptic hybrids are extremely rare (Steeves et al. 2010).|
|♦ Continuing decline in area of occupancy (AOO):||No|
|♦ Extreme fluctuations in area of occupancy (AOO):||No||♦ Estimated extent of occurrence (EOO) - km2:||3300|
|♦ Continuing decline in extent of occurrence (EOO):||No||♦ Extreme fluctuations in extent of occurrence (EOO):||No|
|♦ Number of Locations:||1||♦ Continuing decline in number of locations:||No|
|♦ 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, Sanders and Maloney 2002) 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 (Maloney and Murray 2001). Nests are destroyed, and predation is potentially increased, by drainage and hydroelectric development, weed growth and flood-control programmes (Maloney and Murray 2001), and nesting birds are disturbed by recreational use of riverbeds. Adverse weather and natural flooding are additional, unpredictable threats (Maloney and Murray 2001).
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).