The New Zealand rock wren (''Xenicus gilviventris'') is a small

New Zealand wren The New Zealand wrens are a family (Acanthisittidae) of tiny passerines endemic to New Zealand. They were represented by seven Holocene species in four or five genera, although only two species in two genera survive today. They are understood to ...

(

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Acanthisittidae)

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the

South Island The South Island ( , 'the waters of Pounamu, Greenstone') is the largest of the three major islands of New Zealand by surface area, the others being the smaller but more populous North Island and Stewart Island. It is bordered to the north by ...

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

. Its

Māori Māori or Maori can refer to: Relating to the Māori people * Māori people of New Zealand, or members of that group * Māori language, the language of the Māori people of New Zealand * Māori culture * Cook Islanders, the Māori people of the Co ...

names include ("little complaining bird"), , and ("twitch", after its bobbing motion). Outside New Zealand it is sometimes known as the rockwren to distinguish it from the unrelated rock wren of North America. The rock wren is currently restricted to alpine and subalpine areas of the South Island. It is a poor flier and highly

terrestrial Terrestrial refers to things related to land or the planet Earth, as opposed to extraterrestrial. Terrestrial may also refer to: * Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on o ...

, feeding in low scrub, open

scree Scree is a collection of broken rock fragments at the base of a cliff or other steep rocky mass that has accumulated through periodic rockfall. Landforms associated with these materials are often called talus deposits. The term ''scree'' is ap ...

, and rockfalls. The rock wren and

rifleman A rifleman is an infantry soldier armed with a rifling, rifled long gun. Although the rifleman role had its origin with 16th century hand cannoneers and 17th century musketeers, the term originated in the 18th century with the introduction o ...

are the only two surviving New Zealand wrens; the rock wren's closest relatives were the extinct

stout-legged wren Stout-legged wren is a common name referring to two species of extinct New Zealand wrens: the North Island stout-legged wren or Grant-Mackie's wren (''Xenicus jagmi''), and the South Island stout-legged wren or Yaldwyn's wren (''Xenicus yaldwyni ...

s, followed by the extinct

bushwren The bushwren (''Xenicus longipes''), also known as the in the Māori language, is an extinct species of diminutive and nearly flightless bird that was endemic to New Zealand. It had three subspecies on each of the major islands of New Zealand, ...

. Its numbers are declining due to predation by introduced mammals.

Description

The rock wren is a very small, almost tailless bird that prefers to hop and run on its long legs, and uses its rounded wings to fly only short distances. It's body length is typically about . Males weigh around 16 g, females 20 g. Males are greenish with yellow flanks and a pale underside, females tend to be browner, although the degree of difference between the sexes varies geographically.

Distribution and habitat

This species is currently confined to alpine and subalpine zones (900–2500 m altitude) of the

Southern Alps The Southern Alps (; officially Southern Alps / Kā Tiritiri o te Moana) are a mountain range extending along much of the length of New Zealand, New Zealand's South Island, reaching its greatest elevations near the range's western side. The n ...

, the Tasman Mountains of Northwest Nelson, and the Victoria Range of Westland, all in the South Island; it is New Zealand's only truly alpine bird. Subfossil remains suggest before Polynesian settlement it was also found in lowland forest. DNA from remains previously thought to be of North Island origin were compared with South Island wrens and found to be more closely related to the southern South Island clade. The misidentified North Island specimen is attributed to a mislabeling by the original collector. Its current alpine distribution is a habitat where few rodents can survive, full of sheltering rocks and dense vegetation. Their preferred habitat is close to the treeline, amongst rockfalls,

fellfield A fellfield or fell field comprises the environment of a slope, usually alpine or tundra, where the dynamics of frost (freeze and thaw cycles) and of wind give rise to characteristic plant forms in scree interstices. Soil dynamics The freeze-tha ...

, and low scrub. Rock wrens, unlike many alpine birds, do not migrate to lower elevations in winter; instead, they seem to shelter and forage in rockfalls beneath the snow layer.

Behaviour

The rock wren is a poor flier, rarely flying more than 2 m off the ground or for distances of more than 30 m. It prefers to hop and run with distinctive bobbing and wing flicks. Its call is three high-pitched notes, and pairs sometimes duet. Pairs maintain a year-round territory, and work together to build a large enclosed nest with an entrance tunnel. The nest is lined with feathers, often from other species of birds. Guthrie-Smith recovered 791 feathers from one nest in the 1930s, most from

weka The weka, also known as the Māori hen or woodhen (''Gallirallus australis'') is a flightless bird species of the rail family. It is endemic to New Zealand. Some authorities consider it as the only extant member of the genus '' Gallirallus''. ...

, but including some

kiwi Kiwi most commonly refers to: * Kiwi (bird), a flightless bird native to New Zealand * Kiwi (nickname), an informal name for New Zealanders * Kiwifruit, an edible hairy fruit with many seeds * Kiwi dollar or New Zealand dollar, a unit of curren ...

kākāpō The kākāpō (; : ; ''Strigops habroptilus''), sometimes known as the owl parrot or owl-faced parrot, is a species of large, nocturnal, ground-dwelling parrot of the superfamily Strigopoidea. It is endemic to New Zealand. Kākāpō can be u ...

kea The kea ( ; ; ''Nestor notabilis'') is a species of large parrot in the Family (biology), family Strigopidae that is endemic to the forested and alpine regions of the South Island of New Zealand. About long, it is mostly olive-green, with br ...

, and

kererū The kererū (''Hemiphaga novaeseelandiae''), also known as kūkupa (Māori language#Northern dialects, northern Māori dialects), New Zealand pigeon or wood pigeon, is a species of pigeon native to New Zealand. Johann Friedrich Gmelin describ ...

. Rock wrens are such assiduous collectors of feathers that their nests have been checked for kākāpō feathers, to determine if those endangered parrots are in the area. Around three eggs are laid in late spring and incubated for three weeks. Chicks take about 24 days to fledge and are fed for at least 4 weeks. Rock wrens mostly eat invertebrates on the ground, but will sometimes take berries and seeds, and even nectar from

flax Flax, also known as common flax or linseed, is a flowering plant, ''Linum usitatissimum'', in the family Linaceae. It is cultivated as a food and fiber crop in regions of the world with temperate climates. In 2022, France produced 75% of t ...

flowers.

Conservation

Writing in the 1930s, Herbert Guthrie-Smith declared, This was not to be. Since European settlement in the South Island, rock wrens have become more patchy in their distribution; a study of over 2,100 sightings between 1912 and 2005 showed the area they inhabit had declined significantly since the 1980s. In the

Murchison Mountains The Murchison Mountains () are a group of mountains in Fiordland National Park in New Zealand. It is the location where the South Island takahē, a type of bird presumed extinct, was rediscovered in 1948. The highest mountain is Mount Lyall at . ...

, rock wren showed a 44% decline in abundance over 20 years. The main threats to rock wrens are

stoat The stoat (''Mustela erminea''), also known as the Eurasian ermine or ermine, is a species of mustelid native to Eurasia and the northern regions of North America. Because of its wide circumpolar distribution, it is listed as Least Concern on th ...

s and mice, which eat their eggs and young: A 2012–13 study in the upper Hollyford showed that most rock wren nests were being preyed upon by stoats. Predator trapping improved daily survival rates, egg hatching and fledgling rates of rock wrens. The long-term effect of climate change on their alpine habitat is also a threat, as warmer temperatures will allow rats to move higher into the mountains. In 2008–2010, a total of 40 rock wrens were translocated to

Secretary Island Secretary Island () is an island in southwestern New Zealand, lying entirely within Fiordland National Park. Roughly triangular in shape, it lies between Doubtful Sound / Patea in the south and Te Awa-o-Tū / Thompson Sound in the north, with ...

, an rodent-free island in

Fiordland Fiordland (, "The Pit of Tattooing", and also translated as "the Shadowlands"), is a non-administrative geographical region of New Zealand in the south-western corner of the South Island, comprising the western third of Southland. Most of F ...

, the third-tallest island in New Zealand. In 2010 a survey located 12 unbanded rock wrens, indicating they were successfully breeding. The rock wren was voted New Zealand

Bird of the Year Bird of the Year () is an annual election-based competition run by the New Zealand conservation organisation Forest & Bird to elect a New Zealand native "Bird of the Year". The competition is intended to raise awareness of the conservation thre ...

for 2022.

References

External links

* New Zealand rock wren discussed on RNZ ''

Critter of the Week ''Critter of the Week'' is a weekly RNZ National programme about endangered and neglected native plants and animals of New Zealand. Beginning in 2015, ''Critter of the Week'' is an approximately 15-minute discussion between Nicola Toki (origi ...

''
22 Jan 2016Specimens in the collection of the Museum of New Zealand Te Papa Tongarewa including holotype and syntypes
* {{Authority control Birds of the South Island