Rock wren or pīwauwau - a bird a day

My first – and only – alpine native bird

Rock wren are our only true alpine bird. It is unknown how they survive the harsh climate above the tree line all year round, but it is likely they continue to forage on rocky bluffs where snow has not collected and amongst large boulder fields. Some have suggested they may have a period of semi-hibernation.
Source:
DOC

Rock wren; Image: Kerry Weston | DOC

Kerry Weston sampling rock wren; Image: Gayle Somerville ©

Many aliases

This bird has so many names:
New Zealand rock wren, pīwauwau, piwauwau, mātuitui, matuitui, South Island wren, tuke
Source:
NZ birds online

The New Zealand rock wren (Xenicus gilviventris) is a small New Zealand wren (family Acanthisittidae) endemic to the South Island of New Zealand. Its Māori names include pīwauwau (“little complaining bird”), mātuitui, and tuke (“twitch”, after its bobbing motion). Outside New Zealand it is sometimes known as the rockwren or South Island wren to distinguish it from the unrelated rock wren of North America.
Source:
Wikipedia

Rock wren. Adult male carrying weta to nest. Haast Range, Mt Aspiring National Park, December 2014. Image © David Webb by David Webb

Female rock wren in the Murchison Mountains; Image: James Reardon ©

Rock wren anatomy and decription

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. Males are 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.
Source:
Wikipedia

Xenicis gilviventris, showing distinctive green, yellow, and grey colouring.

Rock wren. Adult female with berry. Otira Valley, April 2018. Image © Oscar Thomas by Oscar Thomas

The New Zealand wrens, Acanthisittidae, are a group that has been isolated for so long from its unknown primitive passerine (the ‘singing’ birds, which make up over half of all living bird species) ancestral stock as to have become an endemic infraorder. This family, including the rifleman, the rock wren (seen on postage stamps), and the bush wren (as well as several extinct species), consists of small, poor-flying and flightless insect-eating birds that have been distributed up and down the length of New Zealand, but are now much more restricted.
Source:
NEW ZEALAND SCIENCE TEACHER
This extract is from a really interesting short article about the evolution of wrens in New Zealand. I recommend reading it – it’s quick, and accessible. The first thing I thought when I looked at these photos was how much they reminded me of the wee rifleman that I drew as part of my native birds design.