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Habitat
In the localities where Leiopelma occurs, types of habitat can be distinguished as follows:—
| (a) Streams or creeks | L. hochstetteri mainly, but L. archeyi (Turbott, 1949, 373), occasionally |
| (b) Bush (forest), either close to or remote from streams | L. archeyi and L. hochstetteri |
| (c) Open country, away from streams | L. archeyi, L. hamiltoni and occasionally L. hochstetteri |
(a) Streams or Creeks.
Only L. hochstetteri is typically found in streams, and even with this species it is quite common to find frogs under stones on the banks instead of in the water. The distribution tends to be localised even within a single stream, the precise nature of the limiting factor being at present obscure.
The type of stream favoured typically contains small waterfalls, cascades and potholes. Stones of all sizes are strewn over the bed, often accompanied by driftwood debris and covered with mosses and liverworts. The surface cover from the surrounding bush vegetation is usually considerable. Behind this marginal vegetation, the taller trees effectively screen out much of the light and help also in preventing air currents. Exceptions from this general rule, however, are known, and the authors on several occasions on Mt. Moehau found L. hochstetteri in parts of streams almost completely free from covering bush.
The frogs are never found in deep water or in the direct path of a current, but prefer quieter reaches where stones are plentiful. Suitable stones for concealment are usually not less than six inches across and are generally flattened. As they lean against each other or against the bank, they form crevices in which the frogs can shelter.
(b) Bush (forest), close to or remote from streams.
Areas on the Tokatea Ridge, some 1,600 feet above sea level, and many regions on the slopes of Mt. Moehau, up to 2,000 feet provide excellent examples of this type of habitat. Included here also is the area near Warkworth where Messrs. Gittos and Turbott found frogs and eggs in wet clay close to a forested stream (Turbott, 1949, 375).
Along the Cape Colville Range, northwards from the Tokatea saddle, bush occurs mainly on the eastern face. Here, in certain localised areas, frogs occur in large numbers. It is in one of these areas (Plate 58, Fig. 1), only a few yards in from the side of a logging track running along the top of the ridge, that specimens of L. hochstetteri were first found in association with L. archeyi (Stephenson and Thomas, 1945, 320). In wet weather temporary creeks may be found coursing down the slope from the ridge, but the nearest permanent stream is approximately half a mile below.
Close to the top of the ridge the bush has a very open character, due partly to logging activities, with a sedge, Uncinia sp. in great abundance in the undergrowth. Logging in the region in question now appears to have ended, which is fortunate from the point of view of survival of the frogs. Much evidence of the activities of wild pigs is present, but there is little indication that they disturb the heavy stones under which Leiopelma shelters.
Further in from the ridge top the bush becomes much denser in character (Plate 58, Fig. 2). Shade is provided by Tawa (Beilschmiedia tawa), Kohekohe (Dysoxylum spectabile), Mahoe (Melicytus ramiflorus), Kawakawa (Macropiper excelsum) and
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Rangiora (Brachyglottis repanda). Tree ferns are plentiful and epiphytes of many kinds common. The latter include many of the moisture loving filmy ferns (Hymeno-phyllum spp.) and it is clear from these and other indications that the relative humidity is high. Mist is very common on the ridge, often lingering for days at a time. Most of the many stones on the forest floor are covered with mosses, ferns and lichens. Further down the slope the bush becomes an exasperating mass of thickly tangled, tough-stemmed supplejack (Rhipogonum scandens).
As in the streams, the larger, more flattened stones are the most favoured by the frogs, and in each case they are set at an angle to the ground, to tree roots, or to other stones, so that crevices are provided. Beneath them are often found tangled roots and smaller stones. Over the crevices hang fern fronds, and they are fringed from below by ground plants. Obviously this screen of vegetation helps in moisture conservation and light elimination.
On the forest-covered portions of the slopes of Mt. Moehau, the vegetation is more montane in character than at Tokatea and varies considerably in density (Moore and Cranwell, 1934; Cranwell & Moore, 1936). Stones are less common than in the Tokatea bush, and the frogs are typically found beneath or even inside decaying logs.
(e) Open country, not associated with streams.
The areas of open country which the authors have examined include the upper slopes and flat areas of the eastern aspect of Mt. Moehau (Plate 56, Fig. 2; Plate 57), and the grassy slopes near the top of the Tokatea Ridge. The latter mainly occur on the western face.
The actual summit peak of Mt. Moehau is covered by a sub-alpine plant association but the extensive areas of open ground around it on the eastern side bear grasses and mosses and other low-growing plants, while lying everywhere are scattered stumps and logs (Plate 57).
South-east from the peak and at a height of over 2,000 feet, is a flat, open, boggy area. Mosses are dominant here, especially the peat-forming Sphagnum sp., Eucamptodon inflatus, and several species of Dicranoloma. Conspicuous among them are two lichens, Cladonia retepora and C. floerkiana, while sedges (Gahnia spp.), rushes (Juncus sp.), and a number of ferns, including Blechnum minor, Gleichenia dicarpa and Paesia scaberula also flourish. Lycopodium fastigiatum and L. laterale are common.
In summer, after a few days of hot, dry weather, helped by the strong winds, the ground quickly dries and hardens on the surface and the plants themselves give evidence of desiccation. Frequent mists and hanging cloud caps, however, help to negate the effects of drying by sun and wind, and the authors themselves have had unpleasant experience of the fact that a sudden storm can turn a hard baked ground into a squelching, waterlogged bog within a few hours; This condition probably persists through a good deal of the winter, and in this season also a light covering of snow has been known to occur on the peak.
The rigorous and changing seasonal conditions on Mt. Moehau make the need of effective shelter imperative for any anuran. Leiopelma archeyi finds this in the dark, still, moist spaces beneath large boulders and stones, in the crevices of decaying tree stumps and fallen logs, and, more temporarily, among clumps of sedges and grasses. As in other localities, the boulders are fringed by plants which act as screens against light and too severe desiccation.
The open country on the Tokatea Ridge consists of grassland which has arisen by clearing and burning of bush. Scattered logs lie among the grass and bracken and surface water is normally absent. Frogs are not numerous, but specimens of L. archeyi and an occasional L. hochstetteri may be found under the logs. As on Mt. Moehau, the prevalent mists presumably play an important part in making such a habitat possible.