Porphyrio hochstetteri

Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

Conservation Actions

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Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
ANIMALIA	CHORDATA	AVES	GRUIFORMES	RALLIDAE

Scientific Name:

Porphyrio hochstetteri

Species Authority:

(Meyer, 1883)

Common Name/s:

English

–

Takahe

Assessment Information [top]

Red List Category & Criteria:

Endangered D ver 3.1

Year Published:

2008

Assessor/s:

BirdLife International

Reviewer/s:

Mahood, S., Butchart, S.

Justification:
This species is listed as Endangered because it has an extremely small, albeit slowly increasing, population. The recovery programme in place aims to establish a self-sustaining population of over 500 individuals. If the population continues to increase, the species will warrant downlisting to Vulnerable in due course.

History:

2006	–	Endangered
2004	–	Endangered
2000	–	Endangered
1996	–	Endangered
1994	–	Not Recognized
1988	–	Not Recognized

Geographic Range [top]

Range Description:	Porphyrio hochstetteri is endemic to New Zealand. Subfossils indicate that it was once widespread in the North and South Islands, but when 'rediscovered' in 1948, it was confined to the Murchison Mountains in Fiordland (c.650 km²)³ and numbered just 250-300 birds⁷. This population has fluctuated between 100-160 birds for the last 20 years⁸ and is thought to be at carrying capacity¹⁶. Translocated populations (1984-1991) exist on four offshore (predator-free) islands - Kapiti, Mana, Tiritiri Matangi and Maud - but have increased only slowly (55 adults in 1998⁶) due to low hatching and fledging rates related to the level of inbreeding of the female of a given pair^3,12. The population on Tiritiri Matangi and other small islands may be close to carrying capacity¹⁴.
Countries:	Native: New Zealand
Range Map:	Click here to open the map viewer and explore range.

Population [top]

Population:	Maxwell (2001); Easons and Williams (2001).
Population Trend:	Increasing

Habitat and Ecology [top]

Habitat and Ecology:	It originally occurred throughout forest and grass ecosystems. Today it is restricted to alpine tussock grasslands on the mainland and feeds primarily on juices from the bases of snow tussock and a species of fern rhizome. It eats introduced grasses on the islands. It usually lays two eggs. Chicks can begin breeding at the end of their first year, but usually start in their second. It is long-lived, probably 14-20 years⁷.
Systems:	Terrestrial

Habitat and Ecology:

It originally occurred throughout forest and grass ecosystems. Today it is restricted to alpine tussock grasslands on the mainland and feeds primarily on juices from the bases of snow tussock and a species of fern rhizome. It eats introduced grasses on the islands. It usually lays two eggs. Chicks can begin breeding at the end of their first year, but usually start in their second. It is long-lived, probably 14-20 years⁷.

Systems:

Terrestrial

Threats [top]

Major Threat(s):	Introduced red deer Cervus elaphus competing for tussock were a major factor in the post-1940s decline¹⁰, while a series of unusually harsh winters appears important in the recent fluctuations^1,3. Predation by introduced stoat Mustela erminea could be significant^2,3,4 but remains speculative⁵. Other potential competitors or predators are introduced brush-tailed possum Trichosurus vulpecula and the threatened Weka Gallirallus australis⁵. The level of inbreeding in females appears to be related to the low hatching and fledging success exhibited by small island populations¹². Radio-tags have been shown to increase daily energy expenditure, this may influence mortality, particularly in hard winters¹³. On some Tiritiri Matangi at least there is probably some predation by Swamp Harrier Circus approximans¹⁵. The small island populations may be close to carrying capacity¹⁴: on Tiritiri Matangi the 2000/2001 breeding season was largely unsuccessful, primarily due to the increase in territorial disputes amoung proximal family groups¹⁵. Habitat quality on some of the islands is probably in decline as reafforestation reduces the area of foraging habitat¹⁵.

Major Threat(s):

Introduced red deer Cervus elaphus competing for tussock were a major factor in the post-1940s decline¹⁰, while a series of unusually harsh winters appears important in the recent fluctuations^1,3. Predation by introduced stoat Mustela erminea could be significant^2,3,4 but remains speculative⁵. Other potential competitors or predators are introduced brush-tailed possum Trichosurus vulpecula and the threatened Weka Gallirallus australis⁵. The level of inbreeding in females appears to be related to the low hatching and fledging success exhibited by small island populations¹². Radio-tags have been shown to increase daily energy expenditure, this may influence mortality, particularly in hard winters¹³. On some Tiritiri Matangi at least there is probably some predation by Swamp Harrier Circus approximans¹⁵. The small island populations may be close to carrying capacity¹⁴: on Tiritiri Matangi the 2000/2001 breeding season was largely unsuccessful, primarily due to the increase in territorial disputes amoung proximal family groups¹⁵. Habitat quality on some of the islands is probably in decline as reafforestation reduces the area of foraging habitat¹⁵.

Conservation Actions [top]

Conservation Actions:	Conservation Actions Underway Since the 1960s, deer have been controlled in the Murchison Mountains. A new mainland population in the Stuart Mountains is being established with surplus birds from the Burwood Bush Captive Rearing facility¹⁶. Island populations of the species are managed intensively, optimising breeding success by supplementary feeding, inter-island transfers (also minimising inbreeding), and egg manipulation (primarily removal of infertile eggs to promote re-nesting)³. Captive-breeding efforts have increased the rate of survival to one year of age (when birds are released into the wild) by 50-60% to 90%⁹. A major review of management in 1996-1997 has been completed⁵. Conservation Actions Proposed Continue to monitor population trends. Continue all aspects of intensive management. Establish a second mainland population. Promote public awareness by holding captive birds for public display and visits to islands, and through the media⁴. Manage the small islands as a metapopulation, with regular transfers of females between islands and periodic introductions of new breeders from the Fiordland population¹². Consider the introduction of birds to another island which could support a larger population. On small islands, plant clumps of native shrubs such as Coprosma spp. at 20-30 metre intervals in open grassy areas to provide cover from C. approximans.

Conservation Actions:

Conservation Actions Underway
Since the 1960s, deer have been controlled in the Murchison Mountains. A new mainland population in the Stuart Mountains is being established with surplus birds from the Burwood Bush Captive Rearing facility¹⁶. Island populations of the species are managed intensively, optimising breeding success by supplementary feeding, inter-island transfers (also minimising inbreeding), and egg manipulation (primarily removal of infertile eggs to promote re-nesting)³. Captive-breeding efforts have increased the rate of survival to one year of age (when birds are released into the wild) by 50-60% to 90%⁹. A major review of management in 1996-1997 has been completed⁵.

Conservation Actions Proposed
Continue to monitor population trends. Continue all aspects of intensive management. Establish a second mainland population. Promote public awareness by holding captive birds for public display and visits to islands, and through the media⁴. Manage the small islands as a metapopulation, with regular transfers of females between islands and periodic introductions of new breeders from the Fiordland population¹². Consider the introduction of birds to another island which could support a larger population. On small islands, plant clumps of native shrubs such as Coprosma spp. at 20-30 metre intervals in open grassy areas to provide cover from C. approximans.

Citation:	BirdLife International 2008. Porphyrio hochstetteri. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. <www.iucnredlist.org>. Downloaded on 26 May 2012.
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