Island Life/XXI

CHAPTER XXI

ANOMALOUS ISLANDS: NEW ZEALAND


 * Position and Physical Features of New Zealand—Zoological Character of New Zealand—Mammalia—Wingless Birds Living and Extinct—Recent Existence of the Moa—Past Changes of New Zealand deduced from its Wingless Birds—Birds and Reptiles of New Zealand—Conclusions from the Peculiarities of the New Zealand Fauna.

The fauna of New Zealand has been so recently described, and its bearing on the past history of the islands so fully discussed in my large work already referred to, that it would not be necessary to introduce the subject again, were it not that we now approach it from a somewhat different point of view, and with some important fresh material, which will enable us to arrive at more definite conclusions as to the nature and origin of this remarkable fauna and flora. The present work is, besides, addressed to a wider class of readers than my former volumes, and it would be manifestly incomplete if all reference to one of the most remarkable and interesting of insular faunas was omitted.

The two great islands which mainly constitute New Zealand are together about as large as the kingdom of Italy. They stretch over thirteen degrees of latitude in the warmer portion of the south-temperate zone, their extreme points corresponding to the latitudes of Vienna and Cyprus. Their climate throughout is mild and equable, their vegetation is luxuriant, and deserts or uninhabitable regions are as completely unknown as in our own islands.

The geological structure of these islands has a decidedly continental character. Ancient sedimentary rocks, granite, and modern volcanic formations abound; gold, silver, copper, tin, iron, and coal are plentiful; and there are also some considerable deposits of early or late Tertiary age. The Secondary rocks alone are very scantily developed, and such fragments as exist are chiefly of Cretaceous age, often not clearly separated from the succeeding Eocene beds.



The position of New Zealand, in the great Southern Ocean, about 1,200 miles distant from the Australian continent, is very isolated. It is surrounded by a moderately deep ocean; but the form of the sea-bottom is peculiar, and may help us in the solution of some of the anomalies presented by its living productions. The line of 200 fathoms encloses the two islands and extends their area considerably; but the 1,000-fathom line, which indicates the land-area that would be produced if the sea-bottom were elevated 6,000 feet, has a very remarkable conformation, extending in a broad mass westward and northward, then sending out a great arm reaching to beyond Lord Howe's Island. Norfolk Island is situated on a moderate-sized bank, while two others, much more extensive, to the north-west approach the great barrier reef, which here carries the 1,000-fathom line more than 300 miles from the coast. It is probable that a bank, less than 1,500 fathoms below the surface, extends over this area, thus forming a connection with tropical Australia and New Guinea. Temperate Australia, on the other hand, is divided from New Zealand by an oceanic gulf about 700 miles wide and between 2,000 and 3,000 fathoms deep. The 2,000-fathom line embraces all the islands immediately round New Zealand as far as the Fijis to the north, while a submarine plateau at a depth somewhere between one and two thousand fathoms stretches southward to the Antarctic continent. Judging from these indications, we should say that the most probable ancient connections of New Zealand were with tropical Australia, New Caledonia, and the Fiji Islands, and perhaps at a still more remote epoch, with the great Southern continent by means of intervening lands and islands; and we shall find that a land-connection or near approximation in these two directions, at remote periods, will serve to explain many of the remarkable anomalies which these islands present.

Zoological Character of New Zealand.—We see, then, that both geologically and geographically New Zealand has more of the character of a "continental" than of an "oceanic" island, yet its zoological characteristics are such as almost to bring it within the latter category—and it is this which gives it its anomalous character. It is usually considered to possess no indigenous mammalia; it has no snakes, and only one frog; it possesses (living or quite recently extinct) an extensive group of birds incapable of flight; and its productions generally are wonderfully isolated, and seem to bear no predominant or close relation to those of Australia or any other continent. These are the characteristics of an oceanic island; and thus we find that the inferences from its physical structure and those from its forms of life directly contradict each other. Let us see how far a closer examination of the latter will enable us to account for this apparent contradiction.

Mammalia of New Zealand.—The only undoubtedly indigenous mammalia appear to be two species of bats, one of which (Scotophilus tuberculatus) is, according to Mr. Dobson, identical with an Australian form, while the other (Mystacina tuberculata) forms a very remarkable and isolated genus of Emballonuridæ, a family which extends throughout all the tropical regions of the globe. The genus Mystacina was formerly considered to belong to the American Phyllostomidæ, but this has been shown to be an error. The poverty of New Zealand in bats is very remarkable when compared with our own islands where there are at least twelve distinct species, though we have a far less favourable climate.

Of the existence of truly indigenous land mammals in New Zealand there is at present no positive evidence, but there is some reason to believe that one if not two species may be found there. The Maoris say that before Europeans came to their country a forest-rat abounded and was largely used for food. They believe that their ancestors brought it with them when they first came to the country; but it has now become almost, if not quite, exterminated by the European brown rat. What this native animal was is still somewhat doubtful. Several specimens have been caught at different times which have been declared by the natives to be the true Kiore Maori—as they term it, but these have usually proved on examination to be either the European black rat or some of the native Australian rats which now often find their way on board ships. But within the last few years many skulls of a rat have been obtained from the old Maori cooking-places, and from a cave associated with moa bones; and Captain Hutton, who has examined them, states that they belong to a true Mus, but differ from the Mus rattus. This animal might have been on the islands when the Maoris first arrived, and in that case would be truly indigenous; while the Maori legend of their "ancestors" bringing the rat from their Polynesian home may be altogether a myth invented to account for its presence in the islands, because the only other land mammal which they knew—the dog—was certainly so brought. The question can only be settled by the discovery of remains of a rat in some deposit of an age decidedly anterior to the first arrival of the Maori race in New Zealand.

Much more interesting is the reported existence in the mountains of the South Island of a small otter-like animal. Dr. Haast has seen its tracks, resembling those of our European otter, at a height of 3,000 feet above the sea in a region never before trodden by man; and the animal itself was seen by two gentlemen near Lake Heron, about seventy miles due west of Christchurch. It was described as being dark brown and the size of a large rabbit. On being struck at with a whip, it uttered a shrill yelping sound and disappeared in the water. An animal seen so closely as to be struck at with a whip could hardly have been mistaken for a dog—the only other animal that it could possibly be supposed to have been, and a dog would certainly not have "disappeared in the water." This account, as well as the footsteps, point to an aquatic animal; and if it now frequents only the high alpine lakes and streams, this might explain why it has never yet been captured. Hochstetter also states that it has a native name—Waitoteke—a striking evidence of its actual existence, while a gentleman who lived many years in the district assures me that it is universally believed in by residents in that part of New Zealand. The actual capture of this animal and the determination of its characters and affinities could not fail to aid us greatly in our speculations as to the nature and origin of the New Zealand fauna.

Wingless Birds, Living and Extinct.—Almost equally valuable with mammalia in affording indications of geographical changes are the wingless birds for which New Zealand is so remarkable. These consist of four species of Apteryx, called by the natives "kiwis,"—creatures which hardly look like birds owing to the apparent absence (externally) of tail or wings and the dense covering of hair-like feathers. They vary in size from that of a small fowl up to that of a turkey, and have a long slightly curved bill, somewhat resembling that of the snipe or ibis. Two species appear to be confined to the South Island, and one to the North Island, but all are becoming scarce, and they will no doubt gradually become extinct. These birds are generally classed with the Struthiones or ostrich tribe, but they form a distinct family, and in many respects differ greatly from all other known birds.

But besides these, a number of other wingless birds, called "moas," inhabited New Zealand during the period of human occupation, and have only recently become extinct. These were much larger birds than the kiwis, and some of them were even larger than the ostrich, a specimen of Dinornis maximus mounted in the British Museum in its natural attitude being eleven feet high. They agreed, however, with the living Apteryx in the character of the pelvis and some other parts of the skeleton, while in their short bill and in some important structural features they resembled the emu of Australia and the cassowaries of New Guinea. No less than eleven distinct species of these birds have now been discovered; and their remains exist in such abundance—in recent fluviatile deposits, in old native cooking places, and even scattered on the surface of the ground—that complete skeletons of several of them have been put together, illustrating various periods of growth from the chick up to the adult bird. Feathers have also been found attached to portions of the skin, as well as the stones swallowed by the birds to assist digestion, and eggs, some containing portions of the embryo bird; so that everything confirms the statements of the Maoris—that their ancestors found these birds in abundance on the islands, that they hunted them for food, and that they finally exterminated them only a short time before the arrival of Europeans. Bones of Apteryx are also found fossil, but apparently of the same species as the living birds. How far back in geological time these creatures or their ancestral types lived in New Zealand we have as yet no evidence to show. Some specimens have been found under a considerable depth of fluviatile deposits which may be of Quaternary or even of Pliocene age; but this evidently affords us no approximation to the time required for the origin and development of such highly peculiar insular forms.

Past Changes of New Zealand deduced from its Wingless Birds.—It has been well observed by Captain Hutton, in his interesting paper already referred to, that the occurrence of such a number of species of Struthious birds living together in so small a country as New Zealand is altogether unparalleled elsewhere on the globe. This is even more remarkable when we consider that the species are not equally divided between the two islands, for remains of no less than ten out of the eleven known species of Dinornis have been found in a single swamp in the South Island, where also three of the species of Apteryx occur. The New Zealand Struthiones, in fact, very nearly equal in number those of all the rest of the world, and nowhere else do more than three species occur in any one continent or island, while no more than two ever occur in the same district. Thus, there appear to be two closely allied species of ostriches inhabiting Africa and South-western Asia respectively. South America has three species of Rhea, each in a separate district. Australia has an eastern and a western variety of emu, and a cassowary in the north; while eight other cassowaries are known from the islands north of Australia—one from Ceram, two from the Aru Islands, one from Jobie, one from New Britain, and three from New Guinea—but of these last one is confined to the northern and another to the southern part of the island.

This law, of the distribution of allied species in separate areas—which is found to apply more or less accurately to all classes of animals—is so entirely opposed to the crowding together of no less that fifteen species of wingless birds in the small area of New Zealand, that the idea is at once suggested of great geographical changes. Captain Hutton points out that if the islands from Ceram to New Britain were to become joined together, we should have a large number of species of cassowary (perhaps several more than are yet discovered) in one land area. If now this land were gradually to be submerged, leaving a central elevated region, the different species would become crowded together in this portion just as the moas and kiwis were in New Zealand. But we also require, at some remote epoch, a more or less complete union of the islands now inhabited by the separate species of cassowaries, in order that the common ancestral form which afterwards became modified into these species, could have reached the places where they are now found; and this gives us an idea of the complete series of changes through which New Zealand is believed to have passed in order to bring about its abnormally dense population of wingless birds. First, we must suppose a land connection with some country inhabited by struthious birds, from which the ancestral forms might be derived; secondly, a separation into many considerable islands, in which the various distinct species might become differentiated; thirdly, an elevation bringing about the union of these islands to unite the distinct species in one area; and fourthly, a subsidence of a large part of the area, leaving the present islands with the various species crowded together.

If New Zealand has really gone through such a series of changes as here suggested, some proofs of it might perhaps be obtained in the outlying islands which were once, presumably, joined with it. And this gives great importance to the statement of the aborigines of the Chatham Islands, that the Apteryx formerly lived there but was exterminated about 1835. It is to be hoped that some search will be made here and also in Norfolk Island, in both of which it is not improbable remains either of Apteryx or Dinornis might be discovered.

So far we find nothing to object to in the speculations of Captain Hutton, with which, on the contrary, we almost wholly concur; but we cannot follow him when he goes on to suggest an Antarctic continent uniting New Zealand and Australia with South America, and probably also with South Africa, in order to explain the existing distribution of struthious birds. Our best anatomists, as we have seen, agree that both Dinornis and Apteryx are more nearly allied to the cassowaries and emus than to the ostriches and rheas; and we see that the form of the sea-bottom suggests a former connection with North Australia and New Guinea—the very region where these types most abound, and where in all probability they originated. The suggestion that all the struthious birds of the world sprang from a common ancestor at no very remote period, and that their existing distribution is due to direct land communication between the countries they now inhabit, is one utterly opposed to all sound principles of reasoning in questions of geographical distribution. For it depends upon two assumptions, both of which are at least doubtful, if not certainly false—the first, that their distribution over the globe has never in past ages been very different from what it is now; and the second, that the ancestral forms of these birds never had the power of flight. As to the first assumption, we have found in almost every case that groups now scattered over two or more continents formerly lived in intervening areas of existing land. Thus the marsupials of South America and Australia are connected by forms which lived in North America and Europe; the camels of Asia and the llamas of the Andes had many extinct common ancestors in North America; the lemurs of Africa and Asia had their ancestors in Europe, as had the trogons of South America, Africa, and tropical Asia. But besides this general evidence we have direct proof that the struthious birds had a wider range in past times than now. Remains of extinct rheas have been found in Central Brazil, and those of ostriches in North India; while remains, believed to be of struthious birds, are found in the Eocene deposits of England; and the Cretaceous rocks of North America have yielded the extraordinary toothed bird, Hesperornis, which Professor O. Marsh declares to have been "a carnivorous swimming ostrich."

As to the second point, we have the remarkable fact that all known birds of this group have not only the rudiments of wing-bones, but also the rudiments of wings, that is, an external limb bearing rigid quills or largely-developed plumes. In the cassowary these wing-feathers are reduced to long spines like porcupine-quills, while even in the Apteryx, the minute external wing bears a series of nearly twenty stiff quill-like feathers. These facts render it almost certain that the struthious birds do not owe their imperfect wings to a direct evolution from a reptilian type, but to a retrograde development from some low form of winged birds, analogous to that which has produced the dodo and the solitaire from the more highly-developed pigeon-type. Professor Marsh has proved, that so far back as the Cretaceous period, the two great forms of birds—those with a keeled sternum and fairly-developed wings, and those with a convex keel-less sternum and rudimentary wings—already existed side by side; while in the still earlier Archæopteryx of the Jurassic period we have a bird with well-developed wings, and therefore probably with a keeled sternum. We are evidently, therefore, very far from a knowledge of the earliest stages of bird life, and our acquaintance with the various forms that have existed is scanty in the extreme; but we may be sure that birds acquired wings, and feathers, and some power of flight, before they developed a keeled sternum, since we see that bats with no such keel fly very well. Since, therefore, the struthious birds all have perfect feathers, and all have rudimentary wings, which are anatomically those of true birds, not the rudimentary fore-legs of reptiles, and since we know that in many higher groups of birds—as the pigeons and the rails—the wings have become more or less aborted, and the keel of the sternum greatly reduced in size by disuse, it seems probable that the very remote ancestors of the rhea, the cassowary, and the apteryx, were true flying birds, although not perhaps provided with a keeled sternum, or possessing very great powers of flight. But in addition to the possible ancestral power of flight, we have the undoubted fact that the rhea and the emu both swim freely, the former having been seen swimming from island to island off the coast of Patagonia. This, taken in connection with the wonderful aquatic ostrich of the Cretaceous period discovered by Professor Marsh, opens up fresh possibilities of migration; while the immense antiquity thus given to the group and their universal distribution in past time, renders all suggestions of special modes of communication between the parts of the globe in which their scattered remnants now happen to exist, altogether superfluous and misleading.

The bearing of this argument on our present subject is, that so far as accounting for the presence of wingless birds in New Zealand is concerned, we have nothing whatever to do with any possible connection, by way of a southern continent or antarctic islands, with South America and South Africa, because the nearest allies of its moas and kiwis are the cassowaries and emus, and we have distinct indications of a former land extension towards North Australia and New Guinea, which is exactly what we require for the original entrance of the struthious type into the New Zealand area.

Winged Birds and Lower Vertebrates of New Zealand.—Having given a pretty full account of the New Zealand fauna elsewhere I need only here point out its bearing on the hypothesis now advanced, of the former land-connection having been with North Australia, New Guinea, and the Western Pacific Islands, rather than with the temperate regions of Australia.

Of the Australian genera of birds, which are found also in New Zealand, almost every one ranges also into New Guinea or the Pacific Islands, while the few that do not extend beyond Australia are found in its northern districts. As regards the peculiar New Zealand genera, all whose affinities can be traced are allied to birds which belong to the tropical parts of the Australian region; while the starling family, to which four of the most remarkable New Zealand birds belong (the genera Creadion, Heterolocha, and Callæas), is totally wanting in temperate Australia and is comparatively scarce in the entire Australian region, but is abundant in the Oriental region, with which New Guinea and the Moluccas are in easy communication. It is certainly a most suggestive fact that there are more than sixty genera of birds peculiar to the Australian continent (with Tasmania), many of them almost or quite confined to its temperate portions, and that no single one of these should be represented in temperate New Zealand. The affinities of the living and more highly organised, no less than those of the extinct and wingless birds, strikingly accord with the line of communication indicated by the deep submarine bank connecting these temperate islands with the tropical parts of the Australian region.

The reptiles, so far as they go, are quite in accordance with the birds. The lizards belong to two genera, Lygosoma, which has a wide range in all the tropics as well as in Australia; and Naultinus, a genus peculiar to New Zealand, but belonging to a family—Geckonidæ—spread over the whole of the warmer parts of the world. Australia, with New Guinea, on the other hand, has a peculiar family, and no less than twenty-one peculiar genera of lizards, many of which are confined to its temperate regions, but no one of them extends to temperate New Zealand. The extraordinary lizard-like Hatteria punctata of New Zealand forms of itself a distinct order of reptiles, in some respects intermediate between lizards and crocodiles, and having therefore no affinity with any living animal.

The only representative of the Amphibia in New Zealand is a solitary frog of a peculiar genus (Liopelma hochstetteri); but it has no affinity for any of the Australian frogs, which are numerous, and belong to eleven different families; while the Liopelma belongs to a very distinct family (Discoglossidæ), confined to the Palæarctic region.

Of the fresh-water fishes we need only say here, that none belong to peculiar Australian types, but are related to those of temperate South America or of Asia.

The Invertebrate classes are comparatively little known, and their modes of dispersal are so varied and exceptional that the facts presented by their distribution can add little weight to those already adduced. We will, therefore, now proceed to the conclusions which can fairly be drawn from the general facts of New Zealand natural history already known to us.

Deductions from the Peculiarities of the New Zealand Fauna.—The total absence (or extreme scarcity) of mammals in New Zealand obliges us to place its union with North Australia and New Guinea at a very remote epoch. We must either go back to a time when Australia itself had not yet received the ancestral forms of its present marsupials and monotremes, or we must suppose that the portion of Australia with which New Zealand was connected was then itself isolated from the mainland, and was thus without a mammalian population. We shall see in our next chapter that there are certain facts in the distribution of plants, no less than in the geological structure of the country, which favour the latter view. But we must on any supposition place the union very far back, to account for the total want of identity between the winged birds of New Zealand and those peculiar to Australia, and a similar want of accordance in the lizards, the fresh-water fishes, and the more important insect-groups of the two countries. From what we know of the long geological duration of the generic types of these groups we must certainly go back to the earlier portion of the Tertiary period at least, in order that there should be such a complete disseverance as exists between the characteristic animals of the two countries; and we must further suppose that, since their separation, there has been no subsequent union or sufficiently near approach to allow of any important intermigration, even of winged birds, between them. It seems probable, therefore, that the Bampton shoal west of New Caledonia, and Lord Howe's Island further south, formed the western limits of that extensive land in which the great wingless birds and other isolated members of the New Zealand fauna were developed. Whether this early land extended eastward to the Chatham Islands and southward to the Macquaries we have no means of ascertaining, but as the intervening sea appears to be not more than about 1,500 fathoms deep it is quite possible that such an amount of subsidence may have occurred. It is possible, too, that there may have been an extension northward to the Kermadec Islands, and even further to the Tonga and Fiji Islands, though this is hardly probable, or we should find more community between their productions and those of New Zealand.

A southern extension towards the Antarctic continent at a somewhat later period seems more probable, as affording an easy passage for the numerous species of South American and Antarctic plants, and also for the identical and closely allied fresh-water fishes of these countries.

The subsequent breaking up of this extensive land into a number of separate islands in which the distinct species of moa and kiwi were developed—their union at a later period, and the final submergence of all but the existing islands, is a pure hypothesis, which seems necessary to explain the occurrence of so many species of these birds in a small area but of which we have no independent proof. There are, however, some other facts which would be explained by it, as the presence of three peculiar but allied genera of starlings, the three species of parrots of the genus Nestor, and the six distinct rails of the genus Ocydromus, as well as the numerous species in some of the peculiar New Zealand genera of plants, which seem less likely to have been developed in a single area than when isolated, and thus preserved from the counteracting influence of intercrossing.

In the present state of our knowledge these seem all the conclusions we can arrive at from a study of the New Zealand fauna; but as we fortunately possess a tolerably full and accurate knowledge of the flora of New Zealand, as well as of that of Australia and the south temperate lands generally, it will be well to see how far these conclusions are supported by the facts of plant distribution, and what further indications they afford us of the early history of these most interesting countries. This inquiry is of sufficient importance to occupy a separate chapter.

169 Dobson on the Classification of Chiroptera (Ann. and Mag. of Nat. Hist. Nov. 1875).

170 See Buller, "On the New Zealand Rat," Trans. of the N. Z. Institute (1870), Vol. III. p. 1, and Vol. IX. p. 348; and Hutton, "On the Geographical Relations of the New Zealand Fauna," Trans. N. Z. Instit. 1872, p. 229.

171 Hochstetter's New Zealand, p. 161, note.

172 The animal described by Captain Cook as having been seen at Pickersgill Harbour in Dusky Bay (Cook's 2nd Voyage, Vol. I. p. 98) may have been the same creature. He says, "A four-footed animal was seen by three or four of our people, but as no two gave the same description of it, I cannot say what kind it is. All, however, agreed that it was about the size of a cat, with short legs, and of a mouse colour. One of the seamen, and he who had the best view of it, said it had a bushy tail, and was the most like a jackal of any animal he knew." It is suggestive that, so far as the points on which "all agreed"—the size and the dark colour—this description would answer well to the animal so recently seen, while the "short legs" correspond to the otter-like tracks, and the thick tail of an otter-like animal may well have appeared "bushy" when the fur was dry. It has been suggested that it was only one of the native dogs; but as none of those who saw it took it for a dog, and the points on which they all agreed are not dog-like, we can hardly accept this explanation; while the actual existence of an unknown animal in New Zealand of corresponding size and colour is confirmed by this account of a similar animal having been seen about a century ago.

173 Owen, "On the Genus Dinornis," Trans. Zool. Soc. Vol. X. p. 184. Mivart, "On the Axial Skeleton of the Struthionidæ," Trans. Zool. Soc. Vol. X. p. 51.

174 The recent existence of the Moa and its having been exterminated by the Maoris appears to be at length set at rest by the statement of Mr. John White, a gentleman who has been collecting materials for a history of the natives for thirty-five years, who has been initiated by their priests into all their mysteries, and is said to "know more about the history, habits, and customs of the Maoris than they do themselves." His information on this subject was obtained from old natives long before the controversy on the subject arose. He says that the histories and songs of the Maoris abound in allusions to the Moa, and that they were able to give full accounts of "its habits, food, the season of the year it was killed, its appearance, strength, and all the numerous ceremonies which were enacted by the natives before they began the hunt, the mode of hunting, how cut up, how cooked, and what wood was used in the cooking, with an account of its nest, and how the nest was made, where it usually lived, &c." Two pages are occupied by these details, but they are only given from memory, and Mr. White promises a full account from his MSS. Many of the details given correspond with facts ascertained from the discovery of native cooking places with Moas' bones; and it seems quite incredible that such an elaborate and detailed account should be all invention. (See Transactions of the New Zealand Institute, Vol. VIII. p. 79.)

175 See fig. in Trans. of N. Z. Institute, Vol. III., plate 12b. fig. 2.

176 Geographical Distribution of Animals, Vol. I., p. 450.

177 In my Geographical Distribution of Animals (I. p. 541) I have given two peculiar Australian genera (Orthonyx and Tribonyx) as occurring in New Zealand. But the former has been found in New Guinea, while the New Zealand bird is considered to form a distinct genus, Clitonyx; and the latter inhabits Tasmania, and was recorded from New Zealand through an error. (See Ibis, 1873, p. 427.)

178 The peculiar genera of Australian lizards according to Boulenger's British Museum Catalogue, are as follows:—Family : Nephrurus, Rhynchœdura, Heteronota, Diplodactylus, Œdura. Family (peculiar): Pygopus, Cryptodelma, Delma, Pletholax, Aprasia. Family : Chelosania, Amphibolurus, Tympanocryptis, Diporophora, Chlamydosaurus, Moloch, Oreodeira. Family : Egerina, Trachysaurus, Hemisphænodon. Family doubtful: Ophiopsiseps.