Invasive Predators in New Zealand

Disaster on Four Small Paws

Carolyn M. King

• Publisher: Palgrave Macmillan
• Year: 2019
• Print ISBN: 9783030321376
• eBook ISBN: 9783030321383
• Topic: Storia
• Subtopic: Storia dell'Australia e dell'Oceania

The story of invasive species in New Zealand is unlike any other in the world. By the mid-thirteenth century, the main islands of the country were the last large landmasses on Earth to remain uninhabited by humans, or any other land mammals. New Zealand's endemic fauna evolved in isolation until first Polynesians, and then Europeans, arrived with a host of companion animals such as rats and cats in tow. Well-equipped with teeth and claws, these small furry mammals, along with the later arrival of stoats and ferrets, have devastated the fragile populations of unique birds, lizards and insects. Carolyn M. King brings together the necessary historical analysis and recent ecological research to understand this long, slow tragedy. As a comprehensive historical perspective on the fate of an iconic endemic fauna, this book offers much-needed insight into one of New Zealand's longest-running national crises.

Part IThe Years Before Cook

© The Author(s) 2019

C. M. KingInvasive Predators in New ZealandPalgrave Studies in World Environmental Historyhttps://doi.org/10.1007/978-3-030-32138-3_1

Begin Abstract

1. Introduction (82 Million Years Ago to AD 1280)

Carolyn M. King¹

(1)

Environmental Research Institute, University of Waikato, Hamilton, New Zealand

Carolyn M. King

Email: [email protected]

Keywords

GondwanaZealandiaGeological historyClimate changeFaunal evolutionPrehuman extinctions

End Abstract

Travelling to New Zealand is the nearest any ordinary folk can get to arriving on another planet. Jared Diamond (1990)¹

Life on a Lonely Island

Charles Darwin , arriving on the Galapagos Islands after long expeditions to observe the continental fauna of South America, was astonished at the variety of animals and plants he found on these strange and remote specks of land so far from the nearest mainland coast. He wrote:

by far the most remarkable feature in the natural history of this archipelago … is that the different islands to a considerable extent are inhabited by a different set of beings … I never dreamed that islands, about fifty or sixty miles apart, and most of them in sight of each other, formed of precisely the same rocks, placed under a quite similar climate, rising to a nearly equal height, would have been differently tenanted.²

Islands are often believed to have a near-magical quality, places to escape enemies, havens of peace and freedom from conflict, protected by open seas that invaders cannot cross. Darwin discovered that island species are just as competitive as any other, but they interact within an environment and community different from those on the mainland, and with a more limited cast of characters.³ The more isolated they are, the less easily they can be influenced by other populations, and so, the more they differ from their relatives.

As island populations accumulate characteristics advantageous to their new environment without being able to exchange genes with their continental relatives, they gradually become distinct from each other over time. Many biologists since Darwin have used islands as ideal natural laboratories for demonstrating how the dynamic nature of life, and the consequences of natural selection in isolation, can produce a range of new species with characters all their own.

Like the Galapagos, the islands of modern New Zealand also comprise an archipelago ideally placed to encourage the evolution of new species (Fig. 1.1). They span 2813 km of the southwest Pacific Ocean—from the subtropical Kermadec group, Raoul and Macauley Islands (29° South) to Campbell Island (52° South). They include the North and South Islands (the ‘mainland’), 114,740 km² and 151,120 km², respectively, sprawled across 1475 km between latitudes 34.4 and 46.6 decimal degrees South, through the Chatham Islands (800 km east of Christchurch) and Stewart Island (30 km south of the South Island) to the subantarctic groups (Snares, Auckland, Campbell, Antipodes and Bounty Islands). These are only the largest of 735 inshore and outlying islands larger than 1 hectare (ha), ranging from fragments separated from the mainland coast by narrow channels to larger chunks of land in distant, splendid isolation.

Fig. 1.1

Map of New Zealand showing places mentioned in the text. (Cartography by Max Oulton)

The total land area of New Zealand adds up to 270,000 km², about the same as the UK but less than 4% of that of Australia, and much more variable in geography and climate than either. All this wonderful diversity means that the habitats offered to animals in the New Zealand region range from temperate coastal bush to high mountains (23 of them reaching to over 3000 m) covered in permanent snow; from rich subtropical forests through near monocultures of hardy mountain beeches to (since only the last couple of million years) the alpine zone; from improved farmland to huge plantations of exotic radiata pine; from limestone caves with constant temperatures to semi-arid tussock-lands with severe winters and hot summers; from swamps to massive freshwater lakes; from small island refuges to modern cities; and in the far south, a scattering of subantarctic islands, and a large slice of Antarctica. For most of the long period from the disappearance of the dinosaurs to the cooling climate of the later Tertiary, that is, from 66 to 10 million years ago (mya), and again, for most of the period since the retreat of the last ice age roughly 10,000 years ago, almost all the dry land below the treeline was covered with tall evergreen forest. More than 80% of it comprised unique species of podocarps (native conifers) or southern beeches (Nothogafaceae) and broadleaved trees, with tree-ferns and shrubs in the under-storey, and native tussock grassland in drier areas and above the treeline.

Animals of one sort or another live in all of these places, so the diversity of wildlife native to these islands is impressive, and their long isolation has compiled an assemblage of species different from everywhere else in the world. New Zealand illustrates brilliantly well how the marvels and perils of life on remote islands are the products of diversification, successive immigrations and extinctions, adaptive radiations and evolutionary interactions. But it also illustrates more clearly than almost anywhere else how the deep-down instability of the restless earth has enforced irresistible dynamic changes on the animals and plants that inhabit its surface. Written in the rocks is the evidence of an unimaginably long and unpredictable history of geological upheavals, whose consequences have sifted through an unending series of variable subsets of animals and plants. The characters in this long saga are part-resident, part-immigrant, thrown together in combinations unknown elsewhere. Those whose lineages have not adapted to each new challenge and to each other have simply disappeared.

The result is an assemblage of biotic communities that has evolved on the New Zealand islands, surviving and changing through tectonic rifting, mountain building, varying sea levels, storms, down-wind drifts, immigrations, extinctions and shipping accidents, surprising enough to northern-hemisphere visitors to have prompted Jared Diamond’s famous remark that ‘Travelling to New Zealand is the nearest any ordinary folk can get to arriving on another planet’.⁴

The Story of New Zealand Wildlife

New Zealand is a large and remote archipelago, protected since the time of the dinosaurs by up to 2000 km of turbulent ocean, deterring intrusion by all but occasional windblown or marine immigrants. In such severe solitude, priceless remnants of early experiments in evolutionary adaptation, which have been extinguished everywhere else, have been preserved alongside new lineages arising from scattered populations stranded by varying sea levels or tectonic uplifts (Fig. 1.2). Together, they formed an entirely new, globally unique feather-based-cum-cold-blooded economy, in which all the ground-dwelling ecological niches filled elsewhere in the world by mammals were occupied by invertebrates, avian and non-avian reptiles and birds . The English, Māori and scientific names of those mentioned in this book are listed in the Appendix.

Fig. 1.2

Relics of Gondwana: two living animals whose ancestry goes back to the time of the dinosaurs. (a) the tuatara; (b) the peripatus or velvet worm, Peripatoides novaezealandiae . (Photographs by Author (a) and Neil Fitzgerald (b))

The absence in modern New Zealand of the terrestrial mammals that have flourished in other countries—not to mention the snakes, dinosaurs and crocodiles, and mammals resident in nearby Australia—is usually explained on the assumption that their ancestors all ‘missed the boat’. But, in fact, the earliest members of all these groups (and their archaic predecessors) were already well established in Australia long before 80 mya.⁵ There must be some other explanation for their absence in New Zealand. There is, but it is not simple.

J.R.R. Tolkien’s masterful trilogy, The Lord of the Rings, is a classic story in three volumes, magically brought to life in Sir Peter Jackson’s three films, all shot in New Zealand. One after another, the three films introduce us to totally unknown creatures that we have never met in the flesh (or would ever want to), but are so believable that thousands of people visit New Zealand to see the places where they were supposed to have lived. The contemporary New Zealand landscape was convincingly portrayed as the Middle Earth of the mythical past, and some of the star-struck visitors are almost surprised to find that orcs and elves no longer live there.

The history of New Zealand’s native fauna is a real-life parallel to Tolkien’s vision. Like Middle Earth, it has been populated by hundreds of creatures totally unfamiliar to us, which played their successive parts over the eras of geological time, the equivalent of Tolkien’s three volumes, against a landscape that has changed out of their ancestors’ recognition and no longer supports any of them. Most of us know nothing of this vanished cast of real creatures, so our understanding of the present tends to be distorted by our unfamiliarity with the past.

This is unfortunate, because the very long and complicated three-stage history of the New Zealand landscape⁶ cannot be understood simply by looking at the species now living there. Fossils tell us of ancestral forms that have never been seen alive by any human eyes and would have been unrecognisable if they had. The latest descendant species often look quite different from the earliest members of their genetic lineage—for example, the extinct giant Haast’s eagle was, at 10–15 kg, one of the largest flying birds that ever lived. Yet, this monstrous predator was descended from a small Australian eagle only a tenth of its size, which arrived in New Zealand a mere 0.7–1.8 mya.⁷

Neither are the living species a random sample of the previous residents, because the winnowing processes set off by environmental changes were strongly biased against the most different and highly specialised species that were once well adapted to long-gone conditions. We know of them only because they left messages to us in their remains, now readable after decades of detailed analyses of fossils and genetic lineages. To appreciate the potential changes we might face in the future, and to put the present conservation crisis into the context of a very, very long history of dynamic changes in native fauna, and not just in New Zealand, it is worth taking some trouble to understand the reasons for the dramatic changes of the past.

The Gondwanan Fauna (82–c.55 Million Years Ago)

The...

Table of contents

• Cover
• Front Matter
• Part I. The Years Before Cook
• Part II. The Years of Accidental Invasions
• Part III. The Years of Deliberate Introductions
• Part IV. What Now?
• Back Matter