rock wren

Some twenty–five years ago, writes Guthrie–Smith, walking from Te Anau to the Sutherland Falls, I had noted on a certain flat-topped rock not far from the top of McKinnon Pass a brace of tiny brown birds — rock wrens they were — curtseying, ducking, and telescoping, exploring the rocks, appearing and reappearing from crannies, fissures, ledges and chinks. More rarely from time to time brief flights were taken, but always the little fellows returned to their boulder as to an established home. I had been thrice across the world since then; war had altered the boundaries of half the States of the Old World; in a dozen departments of human thought science had revolutionized the conceptions of men; yet in the immediate vicinity of that same rude platform the small rock wren had managed to maintain his steadfast hold.

When in 1912 these wilds had been visited it had been Autumn; now it was full spring on the mountainsides. The gritty peat slopes were lightened with innumerable blossoms of the mountain–lily. As single plants or in great irregular clumps, their white flowers high above the deep-green shield shaped leaves dotted and streaked the dips and falls. Among the stone and broken rock debris, often on the very edge of the track, flourished gray silvery Celmisias, some flat on the ground and woolly with soft tomentum, others low shrubs; there were stiff straight Dracophyllums — plants no blast can bend or gale subdue, laden snowberries, prickly heaths, tiered ourisias, pubescent or smooth, whipcord veronicas (hebes), tough stringy brooms, scraps of the vegetable sheep plant, geums, with delicate cherry like blossoms, berried astelias, spear grasses, violets, gentians, edelweiss, mosses, lichens. Mats of wiry high country grasses still lay prone on the ground, flat from the pressure of the previous Winter’s snow. The countryside was a huge rock garden, with an outlook such as no artificial rock garden, from the nature of things, ever possess.

Looking downwards from the top of the pass, the bases of the mountains stood precipitous, sheer, unscalable; above the actual perpendicular cliffs there were gray naked steeps where no fragment of rock rested. Stripped by the elements even of grit, the broken ridges of the great range lay bleached and bare. Here and there whole mountain–sides had slipped in tumbled avalanches of broken rock, each of them forever still, after its one tremendous rush. The little river, no longer muffled beneath its blanket of snow or dumb in emerald ice, sang its gay summer song. So steep was the descent it seemed as though a stone could have been dropped on to the tree tops hundreds of feet beneath.

Birds move so little from localities once discovered to be suitable, that I determined in my mind that the breeding quarters of one pair at least of rock wren would be found near the spot where I had noted them in 1912. I had expected, furthermore, that the nest would be discovered, if discovered at all, built in some dry rock cranny — in some such, in fact, as is selected by the bush wren, Xenicus logipes, — stone, of course, taking the place of timber. I had pictured an unsubstantial domed nest hidden away within the shelter of dry rock.

We did discover our first pair of breeding birds on the summit of the pass, on the very edge of the track, so near that our camera legs straddled it; our photographic gear blocked the King’s narrow highway. At first this was believed to have been a pleasant piece of good fortune; afterwards, when the nestlings were found to have been destroyed, we altered our opinion. We thought then that perhaps had we got a nest farther removed from the path an accident of this sort might have been less likely to happen.

On the top of the pass, first of all we noted a single bird; then that bird, or another, was detected with food in its bill; then the goings and comings of the pair were localized, yard after yard of untraversed ground being discarded from our field of vision. In this most fascinating of all games we grew “warmer” and “warmer”, until in the end my daughter unraveled the mystery by detection of a faint, faint rasp of eager little feeders; searching still more closely, one of the parent birds flew almost into my face. As there were half grown chicks in this nest during the last week of November, and as I found another pair carrying food about the same date, eggs are probably laid in the beginning of the month.

The orifice of the nest pierced into a fibrous mass of overhanging roots. Partly within and partly beneath this densely matted live growth was built the nest. As we discovered afterwards when ransacking the deserted structure, its remarkable bulk was composed of skeleton leaves, finely shredded grass, and feathers. On this comfortable cushion — the feathers were laid most thickly on the bottom of the nest, or, rather, within this overarching bower — reposed the chicks.

Of the 791 feathers counted, over seven hundred were those of Ocydromus australis (weka), and perhaps O. finschi and O. brachypterus. There were feathers also of considerable numbers of the kakapo and kiwi, showing how high these species ascend in their alpine wanderings; there were also a few kea and a few pigeon feathers. When counted by us, in spite of the deluges of the two preceding days, the interior of the nest and the feathers themselves were fresh and sweet, they betrayed no signs of mould or damp.

Unlike the bush wren which is constantly taking dry feathers in and wet feathers out both during incubation of the eggs and rearing of the young, the rock wren seemed to prefer to make a thorough job at the beginning. Warmth and dryness are obtained once for all by bulk of material, the natural oil of the feathers massed together helping to exclude any dampness that might penetrate, firstly through the live root mass, and, secondly, through the exterior shield of shredded grass and skeleton leaves.

The powers of flight are greatly superior to those of the bush wren. The rock wren can fly comfortably fifty or sixty yards, downhill certainly, but with a sustained easy, unlaboured movement — no fern–bird’s feeble flutter. The rock wren, too, is much less of a ground bird in its search for moths and other insect life, often alighting upon and exploring the rounded tops of the shrubby hillside veronicas (hebes); the curtsey or bob, and then the tip–toe telescopic elongation of the little fellow is also more pronounced. However little differences museum specimens may show, there are well marked dis–similarities in the live representatives of X. gilviventris and X. longipes.

Watching the birds at work, we noticed grasshoppers and big whitish spiders carried in for the hungry chicks; more rarely a worm was secured by scratching the drier surfaces of grit and peat. The nest was visited by one or other of the parents about every ten minutes. During the operation of feeding, or perhaps in eager anticipation of the event, the nestlings would emit an almost inaudible rasping cry like the faint winding of a lady’s wrist–watch.

Of the several days devoted to observation of the home life of the rock wren the first alone gave us passable weather. The second was so bitterly bleak that our numb fingers refused their office, entire loss of feeling preventing pressure of the shutter–release. The third day, doubtful from dawn, developed into a terrific gale; torrents of icy rain fell, every precipice and bare slope was gray with innumerable waterfalls, white ragged clouds climbed the cliffs and tore over the tops — really an almost terrifying storm. In weather such as no man ever did bird–nest before, or, I should imagine, ever will again, I persisted for a couple of hours; but, though I came within a few yards of a second nest, cold and misery would not let me rest quiet, and the birds remained unsatisfied as to my presence and refused full confidence. I never found the tiny entrance of that second nest, but, at any rate, discovered that the little pair seemed in no wise perturbed by blasts that nearly whirled me from the mountainside. No doubt during hundreds of centuries the species had become inured to the climatic conditions of Westland.

Xenicus gilviventris, I am glad to think, is one of the species likely to survive changes that from the forester’s and field naturalist’s point of view have desolated New Zealand. The ravages wrought elsewhere by deer, rabbits, opossums, birds, and other imported vermin are unlikely to affect the welfare of the rock wren. Even weasels and rats — and I know they ascend to great heights — are hardly likely to draw sufficient recompense in prey from such unpeopled solitudes. Plant life, furthermore, in these high altitudes and in this showerbath climate is certain to remain undominated by an alien flora. The vegetable kingdom this unaltered, native insect life is consequently secure. With cover and food supplies unmodified, the rock wren may be considered relatively safe.

bush wrens and rock wrens
 
Taxonomy
Kingdom:Animalia
Phylum:Chordata
Class:Aves
Order:Passeriformes
Family:Xeniciddae (Acanthisittidae)
Genera:Xenicus
Species:gilviventris
Sub Species:

Other common names:  — 

Matuhituhi, Hurupounamu

Description:  — 

Endemic bird

10 cm, 16–20g, short tail, rounded wings, long legs and toes. Colour of male is green yellow and cream; female a plainer olive brown. Breeds in October–February.

Where to find:  — 

South Island only, patchy distribution in alpine and sub alpine habitats of the Tasman Mountains, down both sides of the Southern Alps to Fiordland, remain in their territory all year.

Credit for the photograph: — 

 

Marc de Waart

Illustration description: — 

 

Buller, Walter Lawry, Birds of New Zealand, 1873.

Reference(s): — 

 

Heather, B., & Robertson, H., Field Guide to the Birds of New Zealand, 2000.

Oliver, W.R.B. New Zealand Birds, 1955.

Guthrie–Smith, H., Sorrows and Joys of a New Zealand Naturalist, 1936.

Page date & version: — 

 

Wednesday, 13 October, 2010; ver2009v1

 

©  2005    Narena Olliver,    new zealand birds limited,     Greytown, New Zealand.