This bird is found in the South Island on exposed slopes of the Southern Alps, among rocks above the forest line. It is a tiny bird, without a tail, of yellowish-green colour on the back and a rusty-brown beneath; the male and the female are similar but the male is more brightly coloured. The rock wren is slightly larger than the rifleman and, like it, has a high-pitched call. It usually inhabits areas beyond the ordinary haunts of man.
The rock wren makes its nest among boulders which may be covered by snow for some months in midwinter. The nest has a tiny circular opening, about 1 in. in diameter, which leads to a larger globular area made of mosses, leaves, and tussock, and lined with feathers of other birds. These feathers are replaced when they become damp. Both male and female look after the young, and they drag large insects through the tiny opening to feed the fledglings of which two to five are born in spring. The rock wrens have only a short flight, but they have another characteristic, a peculiar bobbing motion which has been described as “knees bend”, by which they may be recognised.
In addition to the rock wren, there is another species, Xenicus longiceps, the bush wren or matuhi. This bird is also very small, of darker green colouring and with a white throat. It is found in damp rimu and beech forests on the West Coast of the South Island, and builds its nest in hollow trees and, like the rock wren, lines it with feathers.
A small bird of similar colouring and size, but of a different genus, Traversia lyallii, now extinct, was known as the Stephens Island wren. Several specimens of this bird were recorded in 1894, but it has not been seen since.
by Olive Rita Croker, M.A., Botanist, Wellington.