Himantopus novaezelandiae
| Kingdom |
Phylum |
Class |
Order |
Family |
| ANIMALIA |
CHORDATA |
AVES |
CHARADRIIFORMES |
RECURVIROSTRIDAE |
| Scientific Name: |
Himantopus novaezelandiae |
| Species Authority: |
Gould, 1841 |
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Common Name/s:
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Assessment Information
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| Red List Category & Criteria: |
Critically Endangered
D
ver 3.1
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| Year Published: |
2009 |
| Assessor/s: |
BirdLife International |
| Reviewer/s: |
Symes, A., Butchart, S., Bird, J. |
| Contributor/s: |
Grant, A., Bayliss, M., Murray, D., Maloney, R. |
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-bred 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.
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| History: |
| 2008 |
– |
Critically Endangered
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| 2007 |
– |
Critically Endangered
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| 2006 |
– |
Critically Endangered
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| 2004 |
– |
Critically Endangered
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| 2000 |
– |
Critically Endangered
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| 1996 |
– |
Critically Endangered
|
| 1994 |
– |
Critically Endangered
|
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Geographic Range
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| 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 are sedentary, but small numbers still overwinter in the North Island. The population may have numbered 500-1,000 birds in the 1940s6, 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 began15. In 2001, the wild breeding population consisted of just seven pairs11, but a maximum of 84 adults were recorded in the wild in August 200213</B. By the 2004-2005 breeding season, there were 11 productive pairs14, and during 2007-2008, that figure had climbed to 20 breeding pairs and a total of 78 mature individuals in the wild17 (although it is not clear how many of these are of captive origin and have not yet bred in the wild). This represents a slight increase overall, but numbers have fluctuated. Fewer than 20 dark H. novaezelandiae \\ H. himantopus hybrids are currently known17. There are not thought to be any cryptic hybrids17. The partial recovery of its population is primarily thanks to the annual release of captive-reared subadults and juveniles (77 and 16 respectively in 2007-200817), and the species's survival remains dependent on captive-breeding efforts until predator-free breeding habitat can be maintained15. The release of more than 80 captive-reared birds near Lake Tekapo in August 2009 increased the free-living population to over 200 individuals17.
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| Countries: |
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| Range Map: |
Click here to open the map viewer and explore range.
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Population
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| Population: |
This estimate 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.
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| Population Trend: |
Increasing
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Habitat and Ecology
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| 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 molluscs19 and small fish8. The species is monogamous and birds pair for life19. 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 duties19. Most breed for the first time at three years of age. The average age is 6.8 years, and two birds are older than 10 years.
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| Systems: |
Freshwater; Marine |
| Major Threat(s): |
Predators, in particular, introduced mammals such as cats, ferret Mustela furo, stoat M. erminea, hedgehogs Erinaceus sp. and brown rat Rattus norvegicus, and the native Australasian Harrier Circus approximans and Kelp Gull Larus dominicanus5,7 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 developments19. Nests are destroyed, and predation is potentially increased, by drainage and hydroelectric development, weed growth and flood-control programmes2,7, and nesting birds are disturbed by recreational use of riverbeds. Adverse weather and natural flooding are additional, unpredictable threats5. Hybridisation with H. himantopus, 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. himantopus females or hybrids4,6,20, although hybridisation has been bidirectional20. Extensive bidirectional hybridisation appears to have been taking place since at least 196020. The sex ratio is now even and the frequency of hybridisation has decreased17,20. 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 species20. Adult mortality in the wild remains very high15. Despite the genetic bottleneck experienced by H. novaezelandiae, there is so far no evidence of inbreeding depression20.
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Conservation Actions
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| 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 testing1. 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 survival16. 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 programme18. Predator exclusion fencing was first installed at the site near Lake Tekapo in the late 1970s19. Trapping for predators around all wild nests has been ongoing since 19974, and research is underway to determine the nature of the threat from each predator species5. Hybrids, now numbering fewer than 20 within the Black Stilt's range, are controlled17. Water-levels are manipulated in managed wetlands to attract birds to feed, and possibly breed, in areas where predators are controlled2. Habitat restoration is ongoing, involving the removal of exotic weeds from riverbeds3. The introduction of a second population on a suitable predator-free island is desirable and has undergone a feasibility study12,17, 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 201119.
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. Establish a self-sustaining population on a predator-free island. Encourage public interest and support9. Seek to maintain predator-free habitat for breeding within the current range. Continue efforts to prevent hybridisation with H. himantopus20. Maintain parity in the adult sex ratio in order to avoid conditions under which introgression with H. himantopus could occur20.
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