Overview

Brief Summary

Biology

Adults are monogamous and pairs generally stay together for life (2). The breeding season peaks in October and both the male and female build the nest that consists of a depression in the ground lined with grass, twigs and waterweeds (3). The pair take it in turns to incubate the four eggs, and care for the chicks (2). Black stilts use their slender beaks to prize prey from underneath stones and to skim through muddy water (4). They feed mainly on aquatic invertebrates, small fish and molluscs (2).
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Description

The New Zealand black stilt, or Kakï, is one of the most threatened wading birds in the world (1). This slender wading bird is very distinctive with its completely black plumage, long red legs and fine black bill (3). Juveniles go through various black and white phases before becoming fully black at around 18 months (4). Eggs are ovoid and light green or brownish olive with dark brown markings (2).
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Distribution

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).
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Range

MacKenzie Basin (South I., New Zealand); winters to North I..

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Historic Range:
New Zealand

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Range

Endemic to New Zealand, the black stilt was once widespread on both the North and South Islands but is today restricted to the Mackenzie Basin on South Island (2).
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Ecology

Habitat

Habitat and Ecology

Habitat and 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.


Systems
  • Freshwater
  • Marine
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Breeding now occurs only within the Mackenzie basin, a high plateau in New Zealand's South Island (5). Most nests are on braided riverbeds (where the river separates, exposing parts of the riverbed), but individuals can also be found on the shores of lakes and in wetlands (6). New Zealand black stilts are partially migratory; some birds move to lower coastal sites prior to winter, and some sub-adults winter in the north of the North Island, whilst others remain in the high basin throughout the year (5).
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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Himantopus novaezelandiae

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 5
Species With Barcodes: 1
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
CR
Critically Endangered

Red List Criteria
D

Version
3.1

Year Assessed
2013

Assessor/s
BirdLife International

Reviewer/s
Butchart, S.

Contributor/s
Bayliss, M., Grant, A., Maloney, R., Murray, D. & Steeves, T.

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.


History
  • 2012
    Critically Endangered
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Current Listing Status Summary

Status: Endangered
Date Listed: 01/16/2008
Lead Region: Foreign (Region 10) 
Where Listed: Entire


Population detail:

Population location: Entire
Listing status: E

For most current information and documents related to the conservation status and management of Himantopus novaezelandiae , see its USFWS Species Profile

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Status

Classified as Critically Endangered (CR) on the IUCN Red List 2007 (1).
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Population

Population
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.

Population Trend
Increasing
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Threats

Major 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).

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The massive decline and retraction in range of the black stilt is mainly attributed to the introduction of mammalian predators to New Zealand such as cats, ferrets and stoats (6). In the Mackenzie Basin, ongoing large-scale rabbit control programmes since the 1940s may have forced feral cats to switch to hunting native birds instead (3). Habitat modification has also contributed to the decline of this species (1); a massive hydroelectric scheme in the basin has considerably altered the natural habitat (7). Today, mammalian predators still represent the major threat to the continued survival of this species along with hybridisation with the closely related Australasian pied stilt, which successfully colonised New Zealand subsequent to European settlement in the 1800's (6). Since the 1970's, the small remnant breeding population of black stilts has been restricted in range to the Mackenzie Basin where it has been intensively protected and managed (5). If numbers continue to fall, hybridisation will become an even bigger problem as individuals find it harder to find mates within their own species.
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Management

Conservation Actions

Conservation Actions
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).

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Conservation

Since the mid-1900's, pure black stilts have numbered fewer than 100 individuals; in 1999, numbers fell as low as 40, only 9 of which were females (6). Since the 1970's, intensive predator control, protection and manipulation of wild nests, and captive breeding and release programmes have been the only factors preventing this species from becoming extinct in the wild (5). The New Zealand Department of Conservation set out a new Kakï Recovery Plan in 2001 (3) in a concerted effort to save this species. Phase one of the plan aims to increase numbers in the wild through captive rearing and release programmes along with predator control measures (3). The second phase of the Recovery Plan aims to identify the causes of breeding failure in the wild (3). Recent improvements in release techniques have increased the initial survival of released birds to as much as 80 to 100 percent and these are encouraging results (6), although factors that inhibit recovery remain.
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Wikipedia

Black Stilt

The Black Stilt or Kakī (Māori), Himantopus novaezelandiae, is a large wader in the avocet and stilt family Recurvirostridae. The species is endemic to New Zealand. Adults are 40 cm long. They have very long red legs, a long thin black bill and black plumage. Juveniles have a white breast, neck and head, with a black patch around the eyes. Unfortunately, the Black Stilt is the world rarest and least populous Charadriiform.

Ecology and conservation[edit]

Despite 20 years of intensive protection, this species remains the rarest wading bird in the world.[2] Intensive management of Black Stilt began in 1981, when the population had declined to just 23 adult birds.[3] The current wild population is estimated at 85 adult birds (February 2010). There is a captive population of some 13 adults. Annual release in the wild of captive-bred birds, and predator control have probably prevented Black Stilt from becoming extinct in the wild. During the breeding season, it is restricted to the Mackenzie Basin in the South Island. The majority of the Black Stilts will also overwinter in the Mackenzie Basin, unlike other waders in the region that migrate to warmer climates for winter.

They breed at 2–3 years of age. They are one of the world's most endangered birds. Drainage and hydroelectric development has in the past disturbed their braided river bed habitat. Predation from mammalian invasive species, most notably mustelids such as stoats, presently poses a serious threat to the survival of the species. The third major threat to this species is hybridization with the local and more numerous Pied Stilt H. himantopus.

Effect of hydroelectric power development[edit]

Because the Black Stilt nests on the braided rivers beds of the South Island, it is threatened by changes in river flows as a result of new hydro dams and changes in flow regimes for existing dams.[4]

The Upper Waitaki Power Development posed a threat to the habitat of the black silt. A program was set up to lessen this threat.[5] The Black Stilt population on the river beds varies with the river level. Changes in the level of Lake Benmore, which caused corresponding changes in the deltas of the incoming rivers, affected the local population of Black Stilts.[6]

References[edit]

  1. ^ BirdLife International (2013). "Himantopus novaezelandiae". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013. 
  2. ^ Rod Morris and Alison Ballance (2008), "Rare Wildlife of New Zealand", Random House, page 113
  3. ^ Maloney, R., and Murray, D. 2002. Kaki (black stilt) recovery plan 2001-2011, NZ Department of Conservation: Wellington.
  4. ^ Reed &, C.E.M.; D.P. Murray (February 1993). Black Stilt Recovery Plan (Himantopus novaezealandiae). Threatened Species Recovery Plan Series NO.4. Wellington, New Zealand: Department of Conservation (New Zealand). ISBN 0-478-01459-7. Retrieved 2008-09-09. 
  5. ^ Ministry for the Environment (May 1998). Flow Guidelines for Instream Values. ME271 Volume B. Wellington, New Zealand: Ministry for the Environment (New Zealand). Retrieved 2008-09-09. 
  6. ^ Sanders, Mark (1999). "Effect of changes in water level on numbers of black stilts (Himantopus novaezelandiae) using deltas of Lake Benmore". New Zealand Journal of Zoology 26 (2). 
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