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The New Zealand Railways Magazine, Volume 14, Issue 9 (December 1, 1939)

Introduced Birds — And Their History — Bird Life in a Mixed Area

page 54

Introduced Birds
And Their History
Bird Life in a Mixed Area

It is September in the Hillsborough district, on the middle Manukau Harbour, and in the cool yet sunny springtime bird-song is at its best and nesting in full swing. This is an area favourable for studying what W. H. Hudson would have called “birds at their best,” and is also one in which the displacement of natives by introduced species is less tinged with regret than it would be, were not the music of blackbird, thrush, skylark and goldfinch the very expression of the furze-pencilled countryside.

It is hard, indeed, to picture what these lovely hills and valleys were in the old Maori days of virgin bush and untouched slopes. Every gully must have held its crowding deeps of forest, sheltered away from the prevailing south-west wind. Only in a few secluded gullies does a remnant of true forest remain, in each of which a tui has taken up his abode—or possibly a pair, clinging on in spite of the changed conditions.

Bird-life being restricted to food supply, it is interesting to note what scrub, bush and farmland offer at this season. The scrub, which has no doubt suffered from cutting and burning, is almost entirely restricted to manuka, interspersed with tutu, karamu, tauhinau (bursting into sulphur-yellow florets) and the waving plumes of the mountain flax. Here and there mapau and wairangi pirau break the foaming waves of grey-green, tea-tree, whose wind-blown tops show a white powdering of flowers. But there is little on the surface of things for bird-food but a rich insect harvest.

In the bush proper the kowhai season is nearly gone, so the tui must have turned to his insect diet. In cultivated fields seamed with golden gorse, worms and snails lurk for thrushes and blackbirds, with thistle for the goldfinch and grasses pushing up shy seed heads which October will bring to fruition.

It has been pointed out by many New Zealand naturalists that among the bird population natives largely keep to the forest and scrub land—to their own haunts where the vegetation is unchanged, and where they can obtain from seed, flower and forest tree the food which is theirs by natural selection; and that introduced birds seldom wander from farmlands, orchard and garden where English conditions prevail. This is specially noticeable on these sea-fronting heights where contrasting conditions meet and mingle. The skylark is seldom over thick scrub where its nest would be buried under manuka; it keeps to the open lands, singing above fields and furze, or wherever axe or fire has cleared a short-cropped way for its running journeys to a grass-hidden nest.

In contrast, the grey warbler, whose home hangs safely suspended from the grey manuka twigs, trills his little warbling song more frequently from the scrub than anywhere else. The waste of tea-tree (manuka) is his home and always was, although the tiny grey and cream-bodied bird has taken more kindly to the changes of civilisation than most of our natives. Warbler, fantail and silver-eye have all adapted themselves to the pastoral face of New Zealand with surprising ease, almost with pleasure; in the case of the warbler, it is hard to account for its increase; for the fantail, the farmer's cows and sheep have provided a banquet of flies; and the silver-eye has gained from an increase of blights with the introduction of fruit trees, chiefly the aphis called American blight.

(W. S. Baverstock, photo.). Mt. Elie de Beaument (10,200 ft.) from Gibb's Creek, Waiho-Weheka Road, South Westland.

(W. S. Baverstock, photo.).
Mt. Elie de Beaument (10,200 ft.) from Gibb's Creek, Waiho-Weheka Road, South Westland.

At this season the silver-eyes are going about in pairs, having deserted the flock habit for mating and nesting, the moss-green and fawn bodies of these dainty little sylphs passing and repassing in happy companionship through fern and karamu to fencing wire, the male indistingnishable from his mate. One wonders which is the leader on these roving explorations, for there is little the silver-eye will not investigate, and one always seems to be the leader, the other following at a short distance, and joyously uttering a musical twitter on catching up to the other, when off again they dart, one after the other.

And what of the tui whose mellow note, drowned almost in a blackbird chorus, sounds at rare intervals from the deeps of bush, rare and precious among the songs of more ordinary birds? Flute-like and mellow, as distinct as the note of a bell, it comes at intervals in rich, full cadence, so much deeper than the blackbird's, whose morning and evening melody ripples from the waving pines with which page 55 some thoughtless planter has sprinkled the bush.

As is well-known, the tui is the earliest singer of the dawn; he is the leader of the morning chorus; the bellbird does not precede his rich, full fluting which begins in darkness and ceases when sunrise flushes the east.

Turning now to the subject of introduced birds which James Drummond has so ably treated, the peculiar harmony of protective colouring is noticeable in a landscape cultivated into the likeness of those from which the birds originally came. Why some species match their surroundings as the leaf insect, folded among leaves whose very veinings are repeated in its wings, it is hard to say, while others like the blackbird draw a streak of jet across their background whenever they move. Those that are the prey of hawks have the greater need of protective coloration, and to a certain extent this rule is followed with many notable exceptions.

The soil is a loamy clay, for the most part harmonising exactly with the sedate earth-grey of larks, that colour which distinguishes the hen-sparrow and henchaffinch from her mate, and which lies thick on the wings of thrushes and the young of goldfinches before the colour comes. It is a colour many might characterise as drab, but it is far otherwise; after the lark has soared and sung, falling lower on the cadence of his rippling finale, watch him drop down on this loamy soil, covered with dead grass and dying furze, and you will hardly detect the long delicate body, so exactly does it match the surroundings.

The vivid goldfinch, too, has a protective colouring more apparent in spring than at any other season, for the golden gleam of his wings is not more brilliant than the blossoming furze on which he loves to sit, or the insignificant yellow eyes of thistle flowers and dandelions. The jet wings and dark red hood, strongly drawn though they are, seem to retreat before this flicker of gold, ever apparent when this loveliest of the finch tribe opens his wings for flight.

Then the linnet, a bird of the grass, has the green-grey look so well suited to the fields he inhabits, but the coral-breasted chaffinch pink pinks from the hedge undisguised, like a flower of the sunset strangely blossoming on a bare hawthorn.

How well defined, too, is the inky silhouette the blackbird draws against his background whenever his strong, deliberate wings open for flight. He is discoverable not only by the magic melody of his spring song but by the sharp scissors-like grind of his fright call, his scolding note of anger.

At an early hour blackbirds are busy with nest-building; their liquid music mainly reserved for morning and evening concerts. With tail spread fanwise they alight on the fencing wire, pausing there as if in thought, a pensive halt, balancing up and down on the narrow perch; then on to some great golden gorse head, with or without a beakful of grass or rootlet, then away into the deeper scrub, the sun-shadowed swathes of grey-green manuka. These provide nesting sites innumerable, but favourite feeding grounds are in the fields of cultivation.

A corner of the Railway Department's plantation at Rotorua.

A corner of the Railway Department's plantation at Rotorua.

How happy these birds appear among the twiggy masses of tea-tree, a growth alien to their natural surroundings in Britain and Europe, the undergrowth of northern deciduous forest having nothing corresponding to it in any way. On this morning of September a blackbird in the gully below was singing a most glorious phase of song over and over again to an accompaniment of whistling thrushes, punctuated every now and then by the rich fluting of a tui.

It is interesting to note the time and place at which old English favourites among birds were imported into New Zealand. In 1862 the Nelson Acclimatisation Society introduced the black-bird (with a shipment of twenty-six); all the other societies followed, and the blackbird was thoroughly established in ten years, penetrating far inland to the mountains and forests where his song echoes all over the country as it does on the other side of the world. Few, if any, of the ordinary British birds are restricted to Britain, and the black-bird's true home includes Europe, North Africa and Asia, as far east as Persia and Turkestan; but it has been successfully acclimatised in many parts of the world.

The same may be said of the thrush; both are old favourites whose haunts and homes are almost inseparably linked. Again, the Nelson Society was first in the field with a shipment of five thrushes in the same year as the black-bird was imported. The thrush was one of the earliest to establish itself through successive importations extending over fifteen years; its gay inconsequent whistle and familiar snail-cracking soon became as frequent as in its northern haunts. And though the excessive rarity of the native thrush (piopio) is much to be deplored, it cannot be put down to the introduction of its relative from the other hemisphere.

The chaffinch, goldfinch, linnet and yellowhammer all made their first appearance in New Zealand in 1862. The Nelson Society imported ten goldfinches in that year, and for the next twenty years these lovely birds continued to arrive in various parts under the auspices of the other Acclimatisation Societies. Europe, North Africa and Western Asia form the natural habitat of the goldfinch, and its familiar flocking among the thistle pastures after breeding is a common sight.

The linnet has the same habit and the same origin; the chaffinch ascends to the upper forest level feeding on insects, fruit and seeds, but like the yellow-hammer is not a native of North Africa, being restricted indigenously to Europe and West Asia.

The skylark with his glorious voice is a denizen of Europe and North Asia, extending over that continent as far as Central China and Northern India. Nelson imported the first larks in 1864; twenty birds arrived safely and up till 1879 they continued to be brought into the country, when seventy were liberated on Stewart Island. Seeds, grain, insects and a small quantity of fruit are page 56 the natural food of the lark, which has become a much more common bird than the native pipit.

Sparrows and starlings, not having been discussed, it is nevertheless interesting to note their history in New Zealand, where they have both become the commonest birds, possibly out-numbering all others. Nelson secured one sparrow in 1862, and we can picture that solitary mateless bird with only two others of its kind in the whole country. These were widely separated from Nelson's bird, for they had arrived in Auckland. Four years later Wanganui had sparrows, and in 1867 Canterbury followed suit; only the Wellington Society was exempt from the guilt of importing our little friend, so familiar and homely a companion of man in most parts of the earth.

It is at once apparent that all these denizens of the Northern Hemisphere have, by seasonal contrast, changed their nesting time from the months of April, May and June to the latter end of the year. Imported species in New Zealand begin building in late August or September; October is the full nesting season, and many continue on through November and December, while late broods are often reared in January. Only in the case of the first birds imported—those that actually made the long sea journey from England—would any difference have been felt owing to the interruption in their sequence of spring nesting. In acclimatising birds to a new country, adaptation to their new surroundings usually occupies them until the spring following their advent, when mating and nesting begin as usual.

(Rly. Publicity photo.) The gannet sanctuary at Cape Kidnappers—about twenty miles south of Napier—the only place in the world where these birds nest on the mainland.

(Rly. Publicity photo.)
The gannet sanctuary at Cape Kidnappers—about twenty miles south of Napier—the only place in the world where these birds nest on the mainland.

The acclimatisation of the nightingale has been tried without success in New Zealand, a pair having been liberated near Auckland some years ago. These birds were heard occasionally for a little while, but they soon disappeared; and as has been pointed out by one of our leading naturalists, the nightingale cannot be expected ever to make its home with us owing to the fact that its migratory instinct cannot adjust itself to unknown pathways over seas and lands of which its inborn sense of direction has no knowledge.

“All attempts to introduce migratory birds will fail,” wrote Hutton in 1901, “as we cannot give them a new instinct, and teach them how to cross the sea.” The Auckland nightingales possibly tried to follow out that inborn urge—perhaps stronger in migratory birds than the sex instinct—and naturally be-wildered and lost in a strange new world, must have perished in obedience to an age-long urge, thus thoughtlessly upset by the agency of man.

W. H. Hudson in his “Adventures Among Birds,” traces the path of the migratory nightingale as passing through France, Spain, across the Strait of Gibraltar, through Algeria and Tripoli to the Sahara and Egypt, thus by Red Sea or Nile Valley to Abyssinia and more southern parts of Africa, travelling “his 4,000 miles or more not by a direct route, but now west and now south, with many changes of direction until he finds his winter home.”

Not only from the migratory point of view but from that of local distribution is the nightingale a tricky bird and one which cannot be successfully acclimatised. Hudson defined its area as restricted to the counties of Hampshire, Surrey and Kent, with fewer in Sussex and Berkshire. “These counties contain more nightingales than all the rest of England together,” he says, and he makes the nightingale's northern boundary extend to South Yorkshire and Shropshire, its western limit ending abruptly on the Welsh borderland and in East Devon. “In Cornwall, Wales, Scotland and Ireland there are no nightingales,” and the bird with such precise and well-defined habits stands to-day much where Hudson left it.

We cannot acclimatise the immortal bird, but in the land of the tui we have no need to attempt it, for the tui is the world's richest, loveliest bird-voice.

With the advance of spring the call of the pipiwharauroa echoes daily among the hills … It is a soft spring evening; dusk has hushed the birds that sing the sunset into obscurity; the last late lark has dropped to earth. Only a few irrepressible thrushes whistle gaily from the bush pines—but one is abroad, fossicking among the copper and ash-grey bracken, roaming hither and thither like a moth, inconsequent and lively as at the first streak of dawn. It is the little riroriro, hunting for a last insect harvest before the shadowy tea-tree sways his tiny fairylike body night-long under the dreaming stars.