Changes in the Flora and Fauna of New Zealand
One of the most important world problems to-day is that of conservation. In all its aspects, whether oil, minerals, timber, food, soil or nature, it is due to the increasing human population. It is the problem of the conservation of nature that I propose to talk about to-day, and only in its relation to New Zealand. For we have in our country a unique and wonderful array of plants and animals mostly occupying unprofitable land, and it is our responsibility to see that they arc preserved as far as possible in their primaeval condition. It is not a problem that can have a final solution It is a matter not only for us but for future generations also. Like peace, the price of preserving our flora and fauna is eternal vigilance.
In my address to the Royal Society last year I took as my subject the history of the legislation dealing with the protection of plants and animals within New Zealand. The laws that have been enacted concern mainly the indigenous plants and animals, but some introduced ones have from time to time been protected for their useful or sporting value. For the present address I propose to take another aspect of the subject of conservation, namely, the changes that have taken place in our flora and fauna as a result of the introduction of man, both Maori and European, and of his attendant plants and animals. The subject is a very large one, so I shall only briefly summarise it and suggest that the measures at present being taken to arrest the unequal contest between the indigenous and the introduced elements be speeded up.
For a very long time, in fact almost the whole of the Tertiary Era, let us say fifty million years. New Zealand enjoyed an isolation that resulted in some unique features in its flora and fauna. When first separated from a continental mass that stretched towards the north-west. New Zealand possessed a flora and a fauna whose immediate associates were afterwards drowned in the Tasman Sea, so that now we have to look far, to Australia or New Guinea, for allied floras and faunas. Secondly, the plants and animals that were thus left to work out their own evolution were lacking such constituents as the eucalypts, acacias and many other characteristic Australian plants: land mammals were absent, while birds and other animals formed a very select group including such remarkable kinds as moas, kiwis and the tuatara.
It is important to note that the plants and animals present when New Zealand was severed from its continental connections were to determine the characteristics of the flora and fauna as they existed when the Polynesians first settled in New Zealand. During the period of isolation there was evolution of new forms and multiplication of species until a highly interesting and unique assemblage of plants and animals came into existence. Forest covered more than two-thirds of the main islands and in many places came down to the water's edge. Only on the high mountains, the centre of the North Island, and some parts of the eastern side of the South Island would there be any
extensive areas of grassland or other types of vegetation. Stragglers there were from Australia during the period of isolation, but these did not much affect the character of the vegetation nor of the fauna that resulted from the evolution of those plants and animals which New Zealand inherited from the continent of which it formerly formed a part. The subject of my address is the fate of the flora and fauna of New Zealand after the islands were invaded by man.
That the Maori people who came to this country in large numbers about 600 years ago found the flora and fauna in its original state is practically certain. True, there had previously been smaller invasions of Polynesians, but not in sufficient numbers to make significant changes in the vegetation. After the main invasion in the fourteenth century, however, marked alterations in the composition and distribution of the flora and fauna were made. For example, considerable areas of forest were replaced by cultivations and subsequently by manuka and bracken scrub, about twenty-six species of moas were exterminated, and a rat and a dog were introduced. The Maori period, as it may be called, lasted until 1840, when Europeans began to arrive in the country in full force. They soon began to change the native vegetation, to reduce the numbers and even the species of birds, and to introduce a host of alien plants and animals that, over most of the country, began to displace the native species.
Let us consider the changes in the flora and fauna wrought by the Maori. The animals that are known to have been introduced by the Maori are the Polynesian rat and the dog. It is unlikely that they had much effect on the native birds, although on Raoul Island in the Kermadee group the same species of rat yearly destroyed many eggs of the till by climbing up to the nests. No doubt therefore in New Zealand the Polynesian rat would take birds' eggs that were within its reach. The Maori is known to have killed moas for food That moa remains have been found in large quantities in swamps could also be put down to the Maori driving the birds in so that they could capture some of them, or the birds may have been seeking shelter in swamps from fires lit by the Maori. This is conjectural, but I am convinced, and I believe others will agree with me, that the final extinction of the moas was due directly to the Maori hunting them for food and for bone with which to make ornaments and other useful articles. Taking a long view, the many species of moa which formerly existed in large numbers and had a long evolutionary history, were exterminated within a few. probably under five, hundred years after the great migration of the Maori from the eastern Pacific to New Zealand.
The effect of the Maori on the forest was considerable in several localities. The area cleared included coastal districts almost all round the North Island and inland in many places, also coastal districts of much of the South Island. These areas are now occupied by manuka, bracken and other shrubby vegetation I do not suggest that, the Maoris seriously altered the vegetative covering of the Canterbury Plains and Central Otago, though a degree of alteration through burning is possible. In 1840 it has been estimated that about 26,000.000 acres of New Zealand were not under forest Possibly the Maoris cleared a tenth of this before the arrival of Europeans.
A few extracts from descriptions of the Maori methods of agriculture will be pertinent at this point An early traveller. Ernest Dieffenbach. said that
forest was destroyed by fire kindled by the Maoris when clearing land for cultivation. “If the land is wooded (and such they prefer) the trees are cut down and burnt.” Richard Taylor said that three years cropping is in general all that can be obtained from one spot, the place then being abandoned, but after a period of from seven to fourteen years the spot is again cleared and planted. It is evident from Taylor's account that forest land required by the Maori to be cleared for planting crops is several times more than that actually in use at any time.
It was during the Maori period that alien plants and animals were first introduced by Europeans. Polack records that the crow garlic was introduced by Marion du Fresne in the Bay of Islands in 1772. It is still abundant in that locality and has spread well over the Auckland province. Crozet, who took command of the expedition after Marion's death, writes: “I formed a garden at Moutouaro Island in which I solved the seed of all sorts of vegetables, stones and pips of our fruits, wheat, millet, maize, and in fact every variety of grain which I had brought from the Cape of Good Hope, everything succeeded admirably…. I planted stones and pips wherever I went, in the plains, in the glens, on flie slopes, and even on the mountains; I also sowed everywhere a few of the different varieties of grain, and most of the officers did the same.” One may be sure that some seeds of weeds were mixed with the others.
Captain Cook, during his second voyage, in 1773, introduced many plants and some animals into New Zealand. As with Crozet, many kinds of vegetable seeds were sown. In 1820, Cruise reported that the plants grown by Cook were numerous but had degenerated. This would, of course, be expected of vegetables such as cabbages, peas, beans, carrots and other kinds whose excellence depends on continuous selection. Cook gave to the Maoris for release, or himself liberated, sheep, pigs, goats and fowls. Of Cook's introductions, pigs and goats apparently became established in a feral state.
More plants and animals were introduced intentionally and unintentionally in the earliest days of settlement at the Bay of Islands and in Otago. Missionaries in the north and sealers and whalers in the south brought in plants and domesticated animals. Rats are known to have come ashore from ships early in the nineteenth century, and we are safe in assuming that weeds and cats too were landed, and so the beginnings of the changes in the flora and fauna we now know were taking place. In 1820 the Russian explorer Bellingshausen distributed seeds of vegetables to the Maoris at Queen Charlotte Sound and explained to them how to put them in the ground. In the next two decades a good deal was done to alter the native vegetation by the agricultural operations of the settlers. After 1840, when immigration proceeded on an ever increasing scale, alien plants and animals came into the country apace, and so was inaugurated the modern age of the replacement of native forests and birds by the immigrants.
For the first thirty years after the arrival of large numbers of Europeans, that is, from about 1840 to 1870, there is very little information available as to what effect the newcomers had on the native vegetation. This is mainly due to the fact that there was during this period no scientific journal printed in New Zealand Now and then, however, we get a glimpse of what was happening For example, Dieffenbach, in 1843, stated that the tuatara, owing to its use by the Maori for food and “no doubt to the introduction of pigs”, was then very
scarce. In the first Annual Report of the Agricultural and Horticultural Society of Auckland, 1843, it is stated that the cape gooseberry “grows wild in every part of the country.”
One of the earliest and most acute observers of our native birds was T. H. Potts. In 1870 he wrote: “The rapid diminution in the numbers of our birds must be apparent to everyone who has given the slightest consideration to the subject”, and again, “many species will have become extinct ere their habits can be sufficiently studied” This prediction unfortunately came true. Potts mentions the quail, rails and the white heron as then becoming scarce. Describing the causes of the disappearance of native birds, he mentions the more remote districts being rendered accessible by roads, draining of swamps, extensive tracts of country being stocked with cattle and sheep and repeated bush fires. Potts notes that, at the time he wrote, the Waste Lands Board of the Province of Canterbury had granted depasturing licences for 189,000 acres of bush land.
The following year Buller had this to say (1871): “In the course of a few years species formerly common in every grove, have become so scarce throughout the country as to threaten their extinction at no very distant date” According to Buller, the Maoris believe that the imported bee is displacing the kaka, tui and other honey-eating birds Judge Maning told Buller that korimakos Mere then Scarcely ever heard, though they once swarmed by thousands, and lie thought that bees had driven them away. However, Buller noted that these birds do not live entirely on nectar and that the tomtit and other species which do not sip flowers are becoming equally scarce. Buller considered that the introduced rat was the chief agent in the rapid destruction of certain species of native birds “This cosmopolitan pest swarms through every part of the country”. said Buller. He noted that the ground lark nests in open grass or fern land where the harrier keeps the rat under control. Travers about this time stated that the kiore or native rat had been displaced by the European rat.
In 1878 D.C. Wilson confirmed Buller's views about the disappearance of birds and the part rats played in the process. Wilson noted that the numbers of kokako had been badly thinned in the previous twenty years. He also noted that the bellbird and the robin had altogether disappeared from his district.
These quotations show that by 1870, that is about thirty years after immigiaion to New Zealand became organised, the position of several of our native species of birds had become serious. The quail and Dieffenbach's rail had passed away and several kinds of bush birds had become reduced in numbers, in some districts disappearing altogether. The main causes had been the clearance of forest and swamps for settlement and the introduction of rats and cats In this same period, 1840 to 1870, the forests of New Zealand were reduced from an estimated 40,000.000 acres to 23,500.000 acres, that is to say nearly half of the forests existing at the commencement of organised European immigration had been destroyed in the space of thirty years.
This first period of thirty years after regular immigration had begun was one of complete recklessness with regard to the clearing of native forests. Within the remaining forest there were taking place the more subtle changes wrought by the animals that, before and during the period, had been introduced and become established. There were pigs and goats landed by Captain Cook, and rats, mice and cats which went into the bush early in the nineteenth
century. The effects of these animals were, however, not so serious as the clearing of forest for settlement.
After about 1870 the destructive agents were to increase and seven more species of birds were to become extinct. As the human population increased and pioneers became farmers, more thought was given to introducing animals for sport and for other reasons, and, as G. M. Thomson puts it, “with zeal unfettered by scientific knowledge, they proceeded to reproduce—as far as possible—the best remembered and more cherished features of the country from which they came” Thus there began an era of widespread replacement in the native flora and fauna. The forces of destruction soon turned into an avalanche and only a few people raised their voices in protest. After 1860 there were four decades of wholesale importation of animals. Widespread establishment and consequent irreparable harm to our forests and birds resulted From 1860 to 1870, red deer, fallow deer, opossums, rabbits and hares were released in numbers sufficient to ensure their naturalization. In the following decade sainbur deer and wallabies were established in certain localities. In the decade 1880 to 1890 there were imported hedgehogs and, by the New Zealand Government, stoats, weasels, ferrets and chamois. There followed a period of ten years without notable importations, but in the first decade of the present century the New Zealand Government Tourist Department, in its endeavour to attract sportsmen from overseas, brought in wapiti, moose. Virginian deer and tahr Thus were our unique forests to be farmed for the benefit of sporting men.
It is only necessary briefly to review the effects on the flora and fauna of this invasion of herbivorous and carnivorous mammals. Public attention has been drawn to it by the press, in books, by protection and scientific societies and, at the present time, by the Government itself which in past times sanctioned the importation of the most destructive species.
The changes in the flora and fauna wrought by the naturalization of exotic plants and animals may be summarized under the headings birds, other animals and plant formations.
The changes in the bird population since the advent of the white man have been truly devastating, though there have been some gains. The losses include nine species exterminated. They are the New Zealand quail, huia and North Island piopio on the main islands, the Chatham Island bellbird. Chatham island fernbird, Chatham Island rail and Dieffenbach's rail on the Chatham Islands; the Stephen Island wren on Stephen Island and the southern merganser on the Auckland Islands. The list of species that have been so reduced in numbers as to be restricted to one or a few localities or at any rate to be scarce or absent in most parts of the country is a long one and includes most of our peculiar forms of bird life—stitchbird, saddlebacks, kokakos, kakapo. South Island piopio, laughing owl, takahe, wekas, robins, brown duck, kiwis. Chatham Island robin, shore plover, marsh crake. Auckland Island duck and rough-faced shag These losses have converted New Zealand from a land where birds were plentiful throughout, to one in which, with a few exceptions, native birds are seldom seen In their place are rats, stoats, ferrets, opossums, cats, little owls and numerous other less harmful exotic birds An entirely changed vegetation covers a great part of the country. Settlements and grazing country replace forests and swamps. Settlement has, however, provided more food for certain species of birds in two ways, the increase of insects and some
plants that goes with cultivated land, and the supply of waste food from human habitations and factories. The abundance of insects and other food in cultivated land has led to increases in such species as tolerate human beings, namely, pipits, harriers, silvereyes, pukeko and stilts. It has also led to enormous increases in introduced species of birds. The refuse of towns and factories has caused our three species of gulls to increase greatly in numbers and it suits several kinds of introduced species particularly sparrows, pigeons and doves.
It is sad to relate that it was during the period of extensive naturalization of exotic animals that commercial collectors made serious inroads on several of our peculiar species of birds. The aim of these men was monetary gain and large numbers of skins were sold to public and private museums in Europe and America. Huias, stitchbirds, piopios, kiwis, kakapos and other endemic species contributed to the wares of this iniquitous trade which, it is certain, was the main cause of the extermination of the huia and four peculiar species of the Chatham Islands. It was thought by some that as the endemic birds of New Zealand would become extinct in any case they may as well be preserved in Museums while there is a chance to take them. Besides commercial exploitation of birds for specimens I might mention the boiling down of penguins for oil on Macquarie Island and the near extermination of fur seals on all the Southern Islands and in the sounds of Fiordland.
Sportsmen must share some of the blame for the changes that have taken place in the avifauna, for they are in part responsible for the introduction of deer and such like which destroy the forests, and sportsmen certainly reduced the numbers of such edible species as ducks, pigeons, quail, kaka and parakeets Pigeons have noticeably increased since they were given protection by Act of Parliament.
The alpine shrubberies, grassland and herbaceous formations, on account of their situation above the forest line, should, one would have thought, been safe from spoliation by exotic animals. This, however, is not so, for two kinds of mountain goats, chamois and tahr, were specially imported to utilise the open mountain tops as a grazing area. To the everlasting shame of those who were responsible for the importation of these destructive animals, what should have remained inviolate as a beautiful flower garden unique in all the world, is now surely being destroyed, at least as a plant formation as nature made it. The officer of the Internal Affairs Department have recently investigated the effects of chamois and tahr on the alpine areas and have noted the following plants as forming the food of these animals: shrubby plants—Gaultheria. Hebe Hoheria. Carmichaelia, Dracophyllum: herbaceous plants—Danthonia, Celmisia. Ranunculus, Aciphylla. Anisotome. The elimination or partial elimination of these plants alters the constitution of the original plant formation and, as Dr. Wodzieki expresses it, leads to a chamois and tahr-induccd plant community.
Though we do not all sympathise with the sportsman, we do forgive the sheep farmer for his part in changing the alpine vegetation, because his products form one of our main primary industries. Some people will not admit that sheep alter the vegetation very much but blame the rabbit. On the Remarkables, however, where Merino sheep but not rabbits ascend to the summit ridge, the only vegetation between about 5,000 and 7,000 feet is dense cushion plant; all the herbaceous kinds such as buttercups, mountain daisies and others
are missing. Thus a decided change in the plant covering has been caused by Merino sheep, a breed which delights to ascend the mountains to the limit of vegetation.
I need not spend any time over the changes which have taken place in our tussock grasslands through the grazing of stock. Sheep and cattle farming requires such country for pasture, but there are still considerable areas which have been little altered by grazing. Rabbits have considerably altered the composition of the grasslands and, at least in Central Otago, have cleared the way for a native cushion plant called scabweed, otherwise Raoulia lutescens. Nor need I refer except briefly to the changes that have taken place in swampy places. Many swamps have been drained and turned into grazing land. The swamp birds, except perhaps the pukeko, suffer, but there are still many swampy areas left for both the botanist and the ornithologist to study.
As regards forests, the effects of deer and pigs have been pointed out in the press, in books and Government pamphlets, in public addresses and over the radio. Every stage of destruction from selective elimination of palatable species to extensive alteration of the forest has been noted. In badly affected areas some species of plants are completely eliminated, seedlings are not allowed to grow, trees are barked and the undergrowth is cleared out. A New Zealand forester has said we cannot have deer and forests together.
What I should like to draw your attention to is the first stage in the alteration of the forest by grazing animals. The seriousness of the earliest damage to the forest has not always been realized, with the consequence that nothing has been done to halt the evil work of deer and pigs in its first stages. It has even been thought that there is no harm in our forests reaching this early stage of destruction. Deerstalkers have capitalized on this misunderstanding and put forward the preposterous suggestion that deer should be allowed to graze in our forests until a certain stage of alteration has been reached, then the deer can be culled so as not to let the forest destruction go too far. Deer stalkers say that if the food consumed were not greater than its annual regeneration no great damage would be done. This in effect would turn the forests into grazing areas that supposedly were not seriously different from the original forests. This is an entirely erroneous notion and utterly disregards the fact that a forest altered to an agreed grazing limit is no longer a primaeval forest but one from which the species most palatable to deer have been eliminated. It is not this mangled forest that all interested in preserving New Zealand's forests in their natural state will be satisfied with. What is wanted is that our forests shall be preserved in our National Parks as nature made them.
The forest in its first stage of destruction may appear to have been little altered, but a botanical examination will soon demonstrate that the more palatable species either have been eliminated or survive only on cliffs, river banks or snags in the streams; that is, places inaccessible to deer. This is the state of affairs in Takahe Valley, where certain herbaceous plants and Tinder-shrubs are found only in a few places in the forest, but are present on cliffs. The lacebark and Nothopanax have practically been exterminated and no seedlings are allowed to grow. On the limestone cliffs are species not found elsewhere—Hebe, Anisotome and others. Obviously deer have cleared out these species from the forest and they are now found only in situations inaccessible
to these animals. To a casual observer the forest appears to be intact, but by studying the distribution of the palatable kinds of plants it can be shown that several species have already practically disappeared where deer browse. A similar state of affairs exists in those parts of Fiordland where deer infestation is as yet slight. This should be taken as a warning that worse will come if measures are not take to chock the deer, and this includes wapiti, la the Caswell Sound area, Poole and Holloway state that on the river levees the brondleaf, the hupiro and species of Nothopanax and Muehlenbeckia have virtually disappeared. Some other shrubs have been eliminated except in inaccessible places. The patete and two species of native broom are typical of these, at this first stage of destruction the forest has already departed from its original state sufficiently to be detected and it has been tragic that in other parts of New Zealand casual examinations of the forests did not reveal the real state of affairs and consequently no early attempts were made to control the deer.
The overall picture of the changes that have come about in our native plants and animals since the advent of man in New Zealand is the widespread destruction of forests and birds. The Maori cleared patches of forest for his agricultural work and then after a few years use abandoned them. At that time regeneration might have restored the forest to its original state as there were in exotic plants like gorse, broom, bramble and hakea to seize the vacant ground. Introduced plants are generally quicker at establishing themselves than are native species, though they cannot penetrate closed formations such as forest and thick scrub. Likewise, the vast increase of rabbits, hedgehogs, sparrows and starlings results from the extensive destruction of native plant formations caused by the white man. But deer, pigs and stoats can flourish in our forests.
It is a moot point how much of the country before man arrived was oocupied by manuka and bracken. It is certain that since the pakeha arrived those areas have increased considerably. They spring up in land that has been cleared of forest or is unfavourable for the growth of trees.
We do not know what part introduced pathological micro-organisms have taken in the reduction of our bird life. There is something mysterious about the total disappearance of the native quail, of the stitchbird from the North Island and of the weka from many districts. Perhaps some disease has overtaken them.
It may be that the timid and secretive opossum will prove a greater threat to our forests than deer and pigs Certainly nothing short of extermination of all three animals will save our forests in anything like their natural state. The Department of Internal Affairs is sparing no effort to collect accurate information about the opossum and its depredations so that effective measures can be taken against it.
What I have said is sufficient to show the far-reaching changes that have taken place in our plant and bird life since the advent of man in New Zealand. What then is the best thing to do to arrest this downward progress? Naturally there comes to mind the idea of eliminating the harmful mammals and birds. This, however, seems impossible on a large area, though in small areas such as the Three Kings and Poor Knights Islands goats and pigs respectively have been exterminated by Government parties. One can only praise the
Government for its work in reducing the numbers of goats, opossums, deer and some other kinds of animals. But could not more help come from the people generally? Deerstalkers, for instance, form a considerable body well armed with rifles. If we could convince them of the great harm done to forests by herbivorous mammals from the very beginning of their invasion, we might bring about a change of outlook so that deerstalkers would shoot to exterminate rather than to select worth-while trophies. What we most need is a more enlightened and assertive public opinion that wall in all parts of the country demand the complete extermination, if humanly possible, of harmful animals, and I am sure that the Government would welcome help in its campaign to rid the country of these pests. Everyone's hand should be against the destroyers of our unique flora and fauna.
One other point is that we should reserve as National Parks, scenic or other reserves, all areas of forest and mountain vegetation not required for economic purposes, and in all cases the administration of such reserves should be specifically charged with keeping down exotic plants and animals therein.