Zosterops lateralis, Latham.
Tau-hou, Kanohi-mowhiti, Poporohe, and Iringatau, of the natives.
Zosterops cœrulescens, Gould. — Hd. Bk. Birds of Australia, Vol. i., p. 587.
Zosterops dorsalis, Vig. and Hors., in Linn. Trans., Vol. xv., p. 235; Gould, Birds of Australia, Fol., Vol. iv., pl. 81.
Sylvia lateralis, Lath.—Ind. Orn. Supp., p. lv.
Certhia cœrulescens, Lath.—Id., p. xxxviii.
Certhia diluta, Shaw.—Gen. Zool., Vol. viii., p. 244.
Philedon cœruleus, Cuvier.
Meliphaga cœrulea, Steph.—Cont. of Shaw's Gen. Zool., Vol. xiv., p. 264.
Sylvia annulosa, var. b.—Sevains. Zool., Ill., 1st. ser., pl. 16.
Zosterops tenuirostris, Gould.—Proc. Z. S., 1837, p. 76.
The story of the irregular appearance of this little bird in New Zealand has for years past been a fruitful topic of discussion among those who take an interest in our local natural history. Whether it came over to us originally from Australia, or whether it is only a species from the extreme south of New Zealand, which has of late years perceptibly increased, and has migrated northwards, is still a matter of conjecture. The evidence which, with Dr. Hector's assistance, I have been able to collect on this subject is somewhat conflicting, but I have myself arrived at the conclusion that the species, whether identical or not with the Australian bird which it closely resembles, is in reality an indigenous one. The history of the species, however, from a North Island point of view is very interesting and suggestive. It appeared on the north side of Cook's Strait, for the first time within the memory of the oldest native inhabitants, in the winter of 1856. In the early part of June of that year I first heard of its occurrence at Waikanae, a native settlement on the west coast, about forty miles from Wellington. The native mailman brought in word that a new bird had been seen, and that it was a visitor from some other land. A week later he brought intelligence that large flocks had appeared, and that the “tau-hou” (stranger) swarmed in the brush-wood near the coast; reporting further that they seemed weary after their journey, and that the natives had caught many of them alive. Simultaneously with this intelligence, I observed a pair of them in a garden hedge, in Wellington, and a fortnight later they appeared in large numbers, frequenting the gardens and shrubberies both in and around the town. They were to be seen daily in considerable flocks, hurrying forwards from tree to tree, and from one garden to another, with a continuous, noisy twitter. In the early morning, a flock of them might be seen clustering together on the topmost twigs of a leafless willow, uttering short plaintive notes, and if disturbed, suddenly rising in the air and wheeling off with a confused and rapid twittering. When the flock had dispersed in the shrubbery, I always observed that two or more birds remained as sentinels or call- birds, stationed on the highest twigs; and that on the slightest alarm, the sharp signal note of these watchers would instantly bring the whole fraternity together. The number of individuals in a flock, at that time, never exceeded forty or fifty, but of late years the number has sensibly increased, it being a common thing now to see a hundred or more consorting together at one time. They appeared to be uneasy during, or immediately preceding, a shower of rain, becoming more noisy and more restless in their movements. They proclaimed
themselves a blessing by preying on and arresting the progress of that noxious aphis known as “American blight” (Schizoneura lanigera).
They remained with us for three months, and then departed as suddenly as they had come. They left before the orchard fruits, of which they are also fond, had ripened, and having proved themselves real benefactors they earned the gratitude of the settlers, while all the local newspapers sounded their well- deserved praises.
During the two years that followed, the Zosterops was never heard of again in any part of the North Island; but in the winter of 1858 it again crossed the strait, and appeared in Wellington and its environs in greater numbers than before. During the four succeeding years it regularly wintered with us, recrossing the strait on the approach of spring. Since the year 1862, when it commenced to breed with us, it has been a permanent resident in the North Island, and from that time it continued to advance northwards. Mr. Colenso, of Napier, reports that it was first seen at Ahuriri in 1862. On his journey to Te Wairoa, in that year, he saw it at Aropauanui, and found its nest containing four fledgelings. The natives of that place told him that it was a new bird to them, they having first observed it there in the preceding year, 1861. The Hon. Major Atkinson, on the occasion of a visit, as Defence Minister, to the native tribes of the Upper Wanganui, in April, 1864, made enquiries on the subject, and was informed by the natives that the Zosterops had appeared in their district for the first time in 1863.
As far as I can ascertain, they penetrated to Waikato in the following year, and pushed their way as far as Auckland in 1865. Captain Hutton reports that in the winter of 1867 they had spread all over the province, as far north as the Bay of Islands, and in 1868 he writes,—“They are now in the most northerly parts of this island.” That they have continued to move on still further northward would appear to be the case from the following interesting notes by Mr. G. B. Owen, communicated to me by Captain Hutton :—” On my passage from Tahiti to Auckland, per brig “Rita,” about 300 miles north of the North Cape of New Zealand, I saw one morning several little birds flying about the ship. From their twittering and manner of flying I concluded that they were land birds, and they were easily caught. They were of a brownish grey and yellowish colour, with a little white mark round the eye. I saw several pass over the ship during the day, travelling northwards. I arrived in Auckland a few days afterwards, on the 20th May, when the so-called Blight Birds appeared here in such numbers, and I at once recognized them as the same.”
This tendency of migration northwards appears to me quite inconsistent with the idea of the species having come to us from Australia.
Now let us ascertain something of its recorded history in the South Island. Mr. Potts, a most careful and experienced observer, writes to me :—
“I first observed it (in Canterbury) after some rough weather, July 28, 1856. I saw about half-a-dozen specimens, on some isolated black birch trees in the Rockwood Valley in the Malvern Hills.” In the Auckland Museum there is a specimen of this bird, sent from Nelson by Mr. St. John (an industrious bird collector), in 1856. The skin was labelled “stranger,” and in the letter accompanying it, Mr. St. John states that these birds had made their first appearance in Nelson that winter (the same in which they crossed to the North Island), and that “no one, not even the natives, had ever seen them before.”
On a visit to Nelson in the winter of 1860, I saw numerous flights of them in the gardens and shrubberies. The results of very careful enquiries on the spot satisfied me that since their first appearance there, in 1856, they had continued to visit Nelson every year, arriving at the commencement of winter, and vanishing on the approach of warmer days as suddenly as they had come. On every hand the settlers bore testimony to their good services in destroying the cabbage blight and other insect pests.
About the middle of June, 1861, I met with small flocks of this bird on the Canterbury Plains, evidently on their passage northward. I first observed them in the low scrub on the broad shingle beds of the Rakaia, advancing in a very hurried manner, not high in the air, as migrations are usually performed, but close to the ground, and occasionally resting. But that this bird is capable of protracted flight is evidenced by the form of its wings, which are of the lengthened, acuminate character, common to most birds of passage.
During a visit to Dunedin, in the summer of 1860, the Rev. Mr. Stack observed numerous flocks in the gardens and thickets in the environs of the town. At this season they had disappeared from the Province of Canterbury and all the country further north. In the following summer (1861), I met with numerous stragglers in the northern parts of the Canterbury Province, and I understand from Mr. Potts, that since that time it has been a permanent resident there, increasing in numbers every year.
Mr. Buchanan, of the Geological Survey Department, informs me that he observed the Zosterops at Otago, on his first arrival there in 1851, five years previous to its appearance in the North Island; and the following extracts from letters, communicated to me by Dr. Hector, go still further to prove that the species is an indigenous one there, and is only new to the country lying further north.
Mr. Newton Watt, R.M., of Campbell Town (Southland), writes as follows:— “Paitu, a chief here, and I believe the oldest man in the tribe, says it was always here. Howell says that he first noticed them on the west coast, about Milford Sound, in the year 1832, in flocks of thirty or forty, but never noticed them here (Riverton) till about 1863, when he saw them inland and in smaller flocks. On my way back from Riverton, I was mentioning it at the Club at Invercargill, and a gentleman present told me he had first noticed
them, about eighty miles inland, about the year 1861, and that his attention was first called to them from the circumstance that they were gregarious,—a habit not common with New Zealand birds. At Campbell Town it appeared to be more scarce, being seen only in small flocks, varying in number from six to twelve. * * * In 1866 my sons noticed numbers of them among my cabbages, and observed that the cats caught many of them; and further, that whilst my cabbages in the three preceding years were infested with blight, in that year there was little or no blight upon them till very late in the season. They appear to migrate from this in the winter, or at any rate to be scarce.”
Mr. James P. Maitland, R.M., of Molyneux, writes:—“From what I hear from old settlers of seventeen or eighteen years standing—whom I can trust as men of observation—I am convinced we have had the birds here for that time at any rate, although all agree that they have become much more numerous everywhere during the last seven years; and this year (1867) in particular, I observe them in larger flocks than ever. I confess I do not recollect noticing the bird until about six years ago; but the smallness of their number at that time, and the smallness of the bird itself, may easily account for its being unnoticed in the bush. The gardens seem to be the great attraction here, and they are the best hands I know at picking a cherry or plum stone clean!”
All my own personal enquiries at Otago, during my first visit there in February, 1865, led me to the same conclusion.
In the selection of its breeding home, this bird has manifested with us the same erratic tendencies: thus, for the first three or four years after its permanent location in the North Island, it wintered in the low lands and the districts bordering on the sea coast, and retired in summer to the higher forest lands of the interior to breed and rear its young. In the summer of 1865, a few stragglers were observed to remain behind all through the season, and in the following year they sojourned in flocks and freely built their nests in our shrub- beries and thickets, and even among the stunted fern and tea-tree (Leptospermum) near the sea shore. From that time to the present it has ranked as one of our commonest birds all the year round; and, what is even more remarkable, it has very perceptibly increased in numbers, while most of our other insectivorous birds are rapidly declining and threaten ere long to be extinct.
To the philosophical naturalist the history of the Zosterops in New Zealand is pregnant with interest, and I feel that no apology is needed for my having thus minutely recorded it.
A specimen which I gave to the Rev. R. Taylor, and forwarded by him to the British Museum, was identified by Dr. J. E. Gray as Zosterops dorsalis. A notice thereof appeared in the Annals of Natural History, and in other scientific papers, and the supposed migration of the species from Australia to New Zealand excited considerable interest. Zosterops dorsalis is found to be identical with Z. lateralis, Latham, and Mr. Gould's Z. cœrulescens is merely a
synonyme of the same species. The last named writer informs us that “this bird is stationary in all parts of Tasmania, New South Wales, and South Australia, where it is not only to be met with in the forests and thickets, but also in nearly every garden.” Dr. Finsch, of Bremen, to whom specimens of the New Zealand bird were forwarded by Dr. Haast, pronounced it Zosterops lateralis, Lath.; while Mr. Waterhouse, of the South Australian Museum, to whom Dr. Hector forwarded examples for examination, considers it distinct from the Australian species “although much resembling it.”
The natives distinguish the bird as Tau-hou (which means “a stranger”), or Kanohi-mowhiti, which may be interpreted spectacle-eye or ring-eye. It is also called Poporohe and Iringatau, names suggested by its accidental or periodical occurrence.
By the settlers it has been variously designated as Ring-eye, Wax-eye, White-eye or Silver-eye, in allusion to the beautiful circlet of satiny-white feathers which surrounds the eyes; and quite as commonly the “Blight Bird,” or “Winter-migrant.”
I have frequently watched the habits of this little bird, and with much interest. As already stated it is gregarious, flying and consorting in flocks, except in the breeding season, when they are to be observed singly or in pairs. As soon as a flock of them alights on a tree, or clump of brush-wood, they immediately disperse in quest of food; and on a cautious approach, may be seen prosecuting a very diligent search among the leaves and flowers, and in the crevices of the bark, for the small insects and aphides on which they principally subsist. I have opened many specimens, at all seasons, and I have invariably found their stomachs crammed with minute insects and their larvæ. In some I have found the large pulpy scale insect (Coccus sp.), of a dull green colour, which is commonly found adhering to the leaves of the ramarama (Myrtus bullata); also small caterpillars, grasshoppers, and coleoptera, and occasionally the small fruity seeds of Rubus australis and other native plants. In our orchards and gardens it regales itself freely on plums, cherries, figs, gooseberries, and other soft fruits, but it far more than compensates for this petty pilfering, by the wholesale war it carries on against the various species of insects that afflict our fruit trees and vegetables. It feeds on that disgusting little aphis known as American Blight, which so rapidly covers with a fatal cloak of white the stems and branches of our best apple trees; it clears our early cabbages of a pestilent little insect that, left unchecked, would utterly destroy the crop; it visits our gardens and devours another swarming parasite that covers our roses and other flowering plants; to say nothing of its general services as an insectivorous bird. Surely in return for these important benefits, to both orchard and garden, the flocks of Zosterops may justly be held entitled to an occasional feed of cherries, or to a small tithe of the ripe fruits which they have done so much to defend and cherish!
This bird emits a soft plaintive cry, repeated at short intervals; but on the wing, and especially when consorting in a flock, it utters a rapid twittering note. During the breeding season the male indulges in a low musical strain of exquisite sweetness, but very subdued, as if singing to himself or performing for the exclusive benefit of his partner. This song is something like the subdued strain of the Korimako (Anthornis melanura), but much softer.
If shot at and wounded it generally manages to escape capture by scrambling nimbly off into the thicket, hiding itself and remaining perfectly silent till the danger has passed.
Frequent attempts have been made to keep it caged, but, although it will readily feed, I have never known it survive confinement many weeks.
Mr. Colenso observes that “when they retire to roost they sleep in pairs, cuddling quite close together like love-parrots; and before they fold their heads under their wings they bill and preen each other's head and neck most lovingly, uttering at the same time a gentle twittering note.”
Mr. Potts informs me that, in Canterbury, this species begins nesting early in October. In one instance, within his own observation, the birds commenced incubation on October 16, the young were hatched on October 25, and left the nest on November 4. In the North Island the breeding season is somewhat later. As late as the 24th of December I met with a nest in the Taupo-Patea country, containing two perfectly fresh eggs.
The nest is a slight, cup-shaped structure, with a rather large cavity for the size of the bird, and is generally found suspended by side fastenings to hanging vines, or to the slender twigs of Leptospermum, Olearia, and other shrubs, and sometimes to the common fern (Pteris aquilina). The eggs are generally three in number (sometimes four), ovoiconical in form, and of a beautiful, uniform pale blue colour.
Nests of this species exhibit some variety, both as to structure and the materials of which they are composed. Of three specimens now before me, one is of slight construction and shallow in its cavity, composed externally of green coloured lichen, spiders' nests, the downy seed-vessels of the pikiarero (flowering clematis) and a few dry leaves; lined internally with long horse- hair disposed in a circular form. Another is of smaller size, more compact, composed externally of crisp, dry moss, and internally of grass bents with a few long hairs interlaced; while the third has the exterior walls constructed entirely of spiders' nests and stiff fibrous mosses, the former predominating, and the interior lining composed wholly of long horse-hair.
A specimen which I found suspended in a clump of creeping kohia (Passiflora tetandra) was composed externally of the pale green and rust- coloured lichen so abundant on the branches of dead timber, intermixed with spiders' webs, and lined inside with dry fibrous grasses, the whole being laced together with hair, the long straggling ends of which projected from every part
of the nest; and another which was obtained from the low brush-wood bordering on the sea shore was built of sheep's wool, spiders' nests, pellets of cow- hair, and fine seaweed, firmly bound together with long thread-like fibres, apparently the rootlets of some aquatic plant, and lined internally with fine grass bents and soft feathers. Sometimes the nest is constructed wholly of bents and dry grass.
Adult.—Crown, sides of the head, nape, upper surface of wings, uropygium and upper tail coverts bright yellowish olive; back and scapularies cinereous tinged with green; eyes surrounded by a narrow circlet of silvery white feathers, with a line of black in front and below. Throat, foreneck, and breast greyish white, tinged more or less with yellow towards the angle of the lower mandible; abdomen and under tail coverts fulvous white; sides pale chocolate brown. Quills and tail feathers dusky brown, margined with yellowish olive; lining of wings white, the edges tinged with yellow. Bill dark brown; under mandible whitish at the base. Irides, tarsi, and toes light brown.
Length 5 inches; extent of wings 7½ wing from flexure 2½ tail 2; tarsus ⅝ middle toe and claw 9–16ths; hind toe and claw ½ bill along the ridge ⅜, along the edge of lower mandible ½.
Young.—A young bird of this species brought to me on the 28th December had the colours paler than in the adult; the throat and breast pale cinereous grey; sides fulvous brown; the white eye circlet absent, the orbits being still destitute of feathers; tarsi and toes light flesh colour; bill pale brown; rictal membrane yellow.*
The characters given above as diagnostic of the genus Zosterops (Vigors and Horsfield) are taken from Gray's Genera of Birds. I have discovered, however, that the present species is in some respects aberrant from the type, and that Mr. Gray's generic characters are not sufficiently comprehensive.
The typical Zosterops has the wing moderate, the first quill very small and the fourth and fifth equal and longest; whereas the species under consideration has the wings long and pointed, the first quill only one-sixteenth of an inch shorter than the second, which is equal to the third, the fourth being scarcely shorter and the rest rapidly graduated. Moreover, the bill which is slightly curved in the typical species, is straight and acuminate in Zosterops lateralis.
These modifications of form, which will be at once apparent on reference to the accompanying figures (Plate III.), may, I think, be considered of sub-generic importance. At any rate, the peculiar adaptation of the wing in our bird to its migratory habits of life is deserving of special notice.
[Footnote] * Since the above paper was written, Archdeacon Stock, who, as the author well remembers, took a lively interest in the Zosterops on its first arrival in 1856, has furnished the following interesting note:—“I saw on Friday last, November 11, at Wilkinson's tea gardens (Wellington), what appeared to be a new variety of the Blight Bird. The white circle around the eye was not so distinct; and the head and throat were orange coloured.”