The Nature Column.

Digger (Invercargill RSA), Issue 2, 26 March 1920, Page 4

The Nature Column.

(BY "STUDENT.")

("Student" will be pleased to receive notes on any branch of Natural History. Observations on birds, insects, plants, etc., will be equally welcome. If using a pen-name, will correspondents please encloso real narne and address.) NATURE ROUND LAKE MONOWAI. Just now, owing to the electrification scheme, a good deal of public attention is focussed on Lake Monowai, and as the writer knows the country surrounding the lake fairly well a few notes on the region may prove of interest. The lake may best be described as "boomerang-shaped." It is only about fifteen or sixteen miles long but to walk round it means an outing of six or seven days. This does not mean that the journey is to be undertaken at or near the water's edge. On the contrary, the only practicable way of getting round is by climbing on the encircling ridge and keeping, for the most part, on the open country, The lake itself is about six hundred feet above sea level while the track of the tripper would lie at from three thousand to five thousand feet up. If the journey is to be begun at the south side of the lake, the best starting point is where a little stream known as Muddy Creek enters the Monowai Flat. Crossing, this a leading spur is located without difficulty and this spur, running close to the lake shore, forms the track for the southem part of the journey, the back of the boomerang. At Muddy Creek the traveller is counselled to boil his billy, or at least to drink deep, for no other drpp of water will he come across for the next six or seven hours. No stream can be expected on the crest of the ridge and the gullies run so steeply down that when rain falls it must all be in the lake in a few hours. This want of watercourses has a striking effect on the bird life. The bush is the ordinary birch forest of the mountains, a kind of bush in which birds are never very abundant. But on this long ridge they are exceptionally scarce. An odd tit may appear here and there, and a few brown creepers may be met with ; at long intervals a fantail's song is heard or a pair of parakeets make their presence known in the tre,e tops. The most common bird is the rifleman, which seems to be always at hand. Tnis, bellbirds, and the gTey warbler seem to be absent altogether though probably, after a wet spell, they come up from the lower bush. The native pigeon is, bowever, quite numerous at times, the reason apparently being to be found in the abundant food supply provided by the peculiar fungus known as the Maori strawberry, which is everywhere plentiful in the upper birch forests. Kakas are very scarce, or absent, and the only introduced birds in evidence are a few blackbirds. The scarcity of bird life on this t.hirsty bush ridge may be set down to ihe want of permanent running water. But we do not mean that the eonnection is direct from stream to bird. Rather, the want of streams means the absence of variety in v.egetation. Every botanist knows that near a watercourse the vegetation is more varied in character than away from the banks of a stream. The lack of variety in vegetation means less insect life, for many kinds of insect are attracted to one particular speciis of plant, and as most of our small birds are wholly or in

part insectivorous we thus arrive at the end of the chain of cause and effect. No doubt down by the— lake shore the birds would be found to be quite as numerous on the southern side as on tlio "northern. But if bird and insect life is scarce on the first poxtion of the Monowai ridge there are not wanting plentiful signs cf other kinds of life. Wild pigs use the crest as a highway, and from Monowai Flat to the open country on the Billow Mountains their rootings are everywhere to be seen. Wild sheep also are not uncommon but the pnesence of so many pigs probably prevents their increase to ahy extent. It is well known that, in the lambing season, wild pigs are responsible for a cons-iderable pereentage of losses. These wikl sheep are Me descendants of i.ccks that were pastured on the open country on the southwest side of the lake -twenty or thirty years ago. None of the high land is used now for sheep, but a few posts still maxk the site of an old holding-yard where the mustered flocks were penned overnight pveparatory to being driven down through the long miles of bush next day. Of deer but few traces are to be seen; perhaps pigs and deer do not care for each others jjompany.

In eonnection with the wild sheep a question arises as to the nlleged depredations of the kea. The bird is common on all the high country surrounding Lake Monowai but yet these sheep rnanage to survive. If the bird is such an inveterate foe of the sheep one would think that these few stragglers, left hehind so many years ago, would have been exterminated long before this. From the v.riter's observations he is inclined to miniinise the losses due to the bird. Certamly sheep may often be seen feoding with several keas hopping ahout in their midst, without the sheep exhibiting the least fear of the birds, or indeed taking the slightest notice of them, and without any sign on the birds' part of a disposition to molest the sheep. But we have over-run our space and we are not halfway round the Lake yet. We will complete the trip in some future issue.