Flight of the Huia

Ecology and conservaton of New Zealand's Frogs, Reptiles, Birds and Mammals

Kerry-Jayne Wilson

• Publisher: Canterbury University Press
• Year: 2016
• eBook ISBN: 9781927145203
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Environmental Science
• Index: Biological Sciences

In the last fifty years New Zealand has become a world leader in the conservation of endangered species. This book is the first to present a history of faunal change in New Zealand and a review of the ecology and conservation of those animals. An invaluable resource for students of ecology and conservation, but written in a highly readable style for the non-specialist.

CHAPTER 1

New Zealand: archipelago and mini-continent

Taking into consideration the peculiarities of the flora and fauna of these islands, and the entire absence of fossil remains indicating a former connection with other continents, we are justified in concluding that, during the whole Tertiary period at least, if not for much longer New Zealand has maintained its isolation from all other extensive tracts of land.

– Alfred R. Wallace (1883)

In the bottom left-hand corner of the world’s largest ocean lies a land once home to some most unusual animals and plants. These species were so unlike those elsewhere that Jared Diamond, the well-known American biologist and author of the book Guns, Germs and Steel, suggested that studying life in New Zealand was the closest he could come to researching on another planet.1 Imagine how our understanding of what is biologically possible would be enhanced by an experiment in evolution independent of life as we know it. We are unlikely to get any such opportunity, and certainly not in our lifetimes, so the best experiments in the independent evolution of life accessible to today’s biologists are to be found on isolated islands such as New Zealand.

Most oceanic islands are geologically young or insufficiently isolated to prevent plants and animals colonising from larger land masses. Diamond identified four island groups that have been isolated for long enough to evolve dramatically different life forms, and are large enough not to be plagued with high natural extinction rates. These are Hawaii, New Caledonia, Madagascar and New Zealand. Of these, he suggests New Zealand is the most interesting. Hawaii is the smallest and youngest; New Caledonia is ancient but small; and Madagascar, while both ancient and large, is too close to Africa to prevent the influx of that continent’s mammals.

Once part of the enormous southern continent known as Gondwana, New Zealand is large, remote, has been isolated from other land masses for 80 million years and lacks the mammals that are dominant elsewhere. At least 80 per cent of the species belonging to most non-marine animal and plant groups are endemic. Some of these species belong to families or orders that occur nowhere else, which illustrates how long they have been separated and how distant their relationships have become. Only other remote islands like Hawaii have a similar proportion of endemic species (Table 1.1).

New Zealand consists of two large islands surrounded by loosely clustered small to moderately large islands. Effectively it is both an archi-pelago and a very small continent. As an archipelago New Zealand is of particular interest because it includes smaller islands of two distinct types. There are numerous land-bridge islands lying close inshore that were connected to the main islands during glacial advances (such as Stewart and Kapiti Islands). Further offshore there are truly oceanic islands that have never had a mainland connection. They range from the subtropical Kermadec Islands to subantarctic Campbell Island, and have been colonised by a subset of species found on the mainland.

Table 1.1 Numbers of native and endemic non-marine bird species breeding on some oceanic and land-bridge islands

		Total species	Endemic species
	Fragments of ancient continents
	New Zealand	104	91 (87%)
	New Caledonia	72	21 (29%)
	Remote, oceanic islands
	Chatham Islands	49	18 (37%)
	Hawaiian Islands	54	49 (90%)
	Land-bridge islands*
	Tasmania	136	13 (10%)
	Borneo	358	37 (10%)

* Land-bridge islands have a smaller proportion of endemic species, owing to colonisation from the neighbouring continent.

Sources: Pratt et al. 1987, Doughty et al. 1999, Simpson & Day 1993, MacKinnon & Phillipps 1993. New Zealand and Chatham Island figures are from Appendix 1 and include mainland species present before 1800.

Figure 1.1 Native and endemic non-marine vertebrate animals breeding in New Zealand and in the British Isles

Since humans discovered New Zealand about 2000 years ago, and permanently colonised this Gondwanan liferaft almost 1200 years later, the natural environment has been greatly altered. Almost a half of the native non-marine birds are extinct, and about half of those that remain are threatened or endangered. Of the endangered or threatened birds listed by Birdlife International in 2000, 5.3 per cent are endemic to New Zealand.2 Considering the country does not have a long list to start with, this is a disproportionately high figure: there are 62 New Zealand species on the list, placing New Zealand eighth equal when counties are ranked this way. All the other countries in the top 25 are larger, and most are tropical nations with far greater species diversity. As well as losing so many species, New Zealand’s ecosystems have been much altered in other ways, with many foreign species introduced and habitats fragmented. Other catastrophic changes are less obvious; for example, the loss of many pollinators and seed dispersers. The integrity of our unique ecosystems is under severe threat.

We can appreciate how different New Zealand is from the intensely studied northern hemisphere ecosystems by comparing our numbers of vertebrate animals with those of the British Isles, a similar-sized temperate archipelago (Figure 1.1). Not only are many New Zealand species endemic, but many belong to families or orders that are restricted to this country (see Chapter 3).

The foundations of ecology were developed in the European and North American temperate zones, and even today most of the world’s ecologists and the headquarters of most environmental organisations are based in that part of the world. Conversely, most endemic birds, most endangered species and the ecosystems under most immediate threat are in the southern hemisphere or the tropics.3

A foreign land

The first Polynesians who came to New Zealand found landscapes, plants and animals very different from those they had previously known. They must have been thrilled to discover a land mass much larger and with a far greater variety of animals than the small, scattered islands whence they came. Not only were there more kinds of animals, but a special bonus was the large, easily hunted, meaty birds. European settlers also found New Zealand to be a foreign land, but for different reasons. They probably expected something resembling their temperate island homeland, and indeed there were superficial similarities, but the ancient evergreen Antipodean forests and their animals were fundamentally different from the open, deciduous forests of Europe.

Initially, neither Polynesian nor European settlers had time to contemplate the strange land, plants and animals, because they were faced with the pressing needs of food and shelter. Just like colonists elsewhere in the world, Maori and Pakeha alike tried to adapt the land to their previous lifestyles, rather than they themselves adapting to the new land. The European settlers were especially assiduous, and it would take several generations for either group to evolve a conservation ethic reflecting the needs of the native animals of this land.

It was long believed that the Maori settlers were the first people to visit these islands. However, during the 1990s it was discovered that kiore (Polynesian rat) had been in New Zealand for about 2000 years, more than a thousand years longer than the earliest likely date of Maori settlement.* They could not have arrived without human assistance, and appear in the subfossil record at about the same time on both main islands. We will probably never know just who those people were that brought the rodents here, as at that time kiore were present on most other South Pacific islands. In a land bereft of mammals, the small ground-dwelling birds and reptiles were defenceless against even this small rat, and we can picture a plague of kiore sweeping across the land with no pied piper to come to the rescue. By the time the Polynesians settled New Zealand around AD1200 (see Chapter 5), many of the small ground-dwelling birds, reptiles,...

Table of contents

• Cover
• Title Page
• CONTENTS
• PREFACE
• ACKNOWLEDGEMENTS
• CHAPTER 1: New Zealand: archipelago and mini-continent
• CHAPTER 2: New Zealand’s frogs and reptiles
• CHAPTER 3: Ecology of birds and bats
• CHAPTER 4: Vertebrate communities in pre-human New Zealand
• CHAPTER 5: Extinctions of New Zealand vertebrates
• CHAPTER 6: Acclimatisation
• CHAPTER 7: The forest vertebrate community in the twentieth century
• CHAPTER 8: Seabirds and marine mammals
• Chapter 9: Conservation
• Chapter 10: Seeking solutions
• APPENDIX 1: A checklist to the amphibians, reptiles, mammals and birds of New Zealand
• APPENDIX 2: Plant, invertebrate, marine, foreign bird and foreign mammal species mentioned in the text
• NOTES
• REFERENCES
• Index
• Plates
• Copyright