Background to Invasive Reptiles and Amphibians

Alien Reptiles and Amphibians INVADING NATURE - SPRINGER SERIES IN INVASION ECOLOGY Volume 4 Series Editor: JAMES A. DRAKE University of Tennessee, Knoxville, TN, U.S.A. For other titles published in this series, go to www.springer.com/series/7228 Fred Kraus Alien Reptiles and Amphibians A Scientiﬁ c Compendium and Analysis Fred Kraus Bishop Museum 1525 Bernice St. Honolulu, HI 96817 USA ISBN 978-1-4020-8945-9 e-ISBN 978-1-4020-8946-6 Library of Congress Control Number: 2008932568 © 2009 Springer Science + Business Media B.V. No part of this work may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without written permission from the Publisher, with the exception of any material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work. Cover illustration: Cover figure on the right by David Preston, Bishop Museum Printed on acid-free paper springer.com For Ezra, in gratitude for her gracious love and tolerance Preface Transportation of species to areas outside their native ranges has been a feature of human culture for millennia. During this time such activities have largely been viewed as beneficial or inconsequential. However, it has become increasingly clear that human-caused introductions of alien biota are an ecological disruption whose consequences rival those of better-known insults like chemical pollution, habitat loss, and climate change. Indeed, the irreversible nature of most alien-species introductions makes them less prone to correction than many other ecological problems. Current reshuffling of species ranges is so great that the present era has been referred to by some as the “Homogocene” in an effort to reflect the unique magnitude of the changes being made. These alien interlopers often cause considerable ecological and economic damage where introduced. Species extinctions, food-web disruptions, community altera- tions, ecosystem conversion, changes in nutrient cycling, fisheries collapse, watershed degradation, agricultural loss, building damage, and disease epidemics are among the destructive – and frequently unpredictable – ecological and economic effects that invasive alien species can inflict. The magnitude of these damages con- tinues to grow, with virtually all environments heavily used by humans now domi- nated by alien species and many “natural” areas becoming increasingly prone to alien invasion as well. Attention to this problem has increased in the past decade or so, and efforts to prevent or limit further harm are gaining wider scientific and political acceptance. Scientific and managerial attention to invasive aliens is not, however, distributed equally across all plant and wildlife species. Most research and management efforts involving terrestrial invasives have been showered on mammals, plants, and insects. This is unsurprising because many of these organisms cause tremendous amounts of damage, so focus on them is reasonable and justified. But this practice also leads to an often unstated presumption that those alien organisms not featured in books, newspapers, magazines, or scientific journals must not be causing problems. That may be true; but it need not be, and it may not be as a general rule. The rub, of course, is that the only way to be sure of presumptive harmlessness is to directly investigate the less-recognized, unstudied alien species – studies lacking precisely because of the presumption. Thus are we mired in a Catch-22. vii viii Preface Reptiles and amphibians are among those alien taxa whose introductions have largely been ignored. And yet their introduction has become common and widespread, although it is difficult to appreciate the scale of this phenomenon from the widely scattered references in a frequently obscure literature. Partly for this reason, herpetological introductions have received scant attention from policy mak- ers, land managers, and researchers. Hence, a scientific compendium of the topic is warranted, and I attempt to provide that here. I present here a database of amphibian and reptile introductions – based on the published literature and of global ambit – so as to analyze how these introductions are occurring. The database is provided in Appendix 1 and comprises a large portion of the present book. Complementary to this is a bibliography of approximately 4,000 supporting references. But what matters as much as providing these raw data is placing them in context and determining what they signify. This is addressed in the several chapters that precede the database. Because this book is not addressed solely to specialists on invasive species, the first chapter provides a short overview of alien invasions and human responses, then briefly summarizes the history of how study of herpetological invasions has developed. The remaining chapters focus on alien reptiles and amphibians in particular. Chapter 2 uses the database to analyze how reptiles and amphibians have been transported by humans and how those patterns change spa- tially and through time. Knowledge of these mechanisms and patterns is requisite for preventing future introductions. Chapter 3 summarizes the detrimental impacts documented to result from introductions of alien herpetofauna. Chapter 4 examines management responses that have been taken against herpetological invasions and what factors limit the effectiveness of those responses. The final chapter examines the logical implications that the data presented in earlier chapters have for design- ing appropriate management programs. It also identifies research needs for improv- ing understanding and management of reptile and amphibian introductions. Comprehensive summaries or analyses of the topics treated in Chapters 2–5 are currently lacking in the literature. I take it as axiomatic that scientists have a responsibility to help society solve its problems and challenges. Consistent with this belief, this book is explicitly con- cerned with applying scientific data to a practical conservation problem; hence, the book may appear more applied that is common for the standard academic tome. I have three aims for this book. The first is to document that alien reptiles and amphibians are a valid conservation problem that warrants a broader management response than it has yet received. Chapters 2 and 3 are most relevant to that goal. Evidence contained in both should improve recognition within the scientific and policy-making communities of the magnitude of herpetofaunal changes now occurring and, ideally, stimulate more action toward ameliorating this unprecedented and uncontrolled experiment in biological mixing. The current evidence suggests that continued managerial inaction is not a responsible option. The second goal is to identify what managerial and research actions are neces- sary to meet this conservation challenge. Accordingly, I examine what practical and research efforts have been directed toward these organisms and suggest how both pursuits can be improved. So as to make it logistically easier for future research to Preface ix proceed I provide the database compiling the majority of the published literature on this topic. There is increasing interest in invasive reptiles and amphibians among students, but it is commonly difficult for them to discover relevant literature. In providing a compilation of introductions and the large majority of their supporting literature in one source I hope to make it more attractive and feasible for a new generation to pursue research on the ecological and evolutionary ramifications of these introductions, as well as their solutions. Thirdly, much of the aesthetic and ecological harm inflicted on native herpeto- faunas by alien introductions stems, ironically, from the activities of many who have a love for these animals. This book will make clear the extent to which care- less or arrogant pet fanciers and an indifferent pet industry have been responsible for this harm. It is my hope that making this pattern clear will lead to some critical self-examination and behavioral changes among this cohort of herpetophiles. A special circle in heaven is reserved for those who have assisted me with obtain- ing literature incorporated into this database or used in the introductory chapters. I am happy to report that Harald Artner, Aaron Bauer, Mark Bayless, Mary Bomford, Lea’ Bonewell, Roger Bour, Chris Buddenhagen, Russ Burke, Earl Campbell, Todd Campbell, Jack Crayon, Ron Crombie, Indraneil Das, Chris Dionigi, Sandy Echternacht, Kevin Enge, Antoine Fouquet, Tom Fritts, Darrel Frost, Pam Fuller, Trent Garner, Eli Greenbaum, Heinz Grillitsch, Ivan Ineich, John Iverson, Fabio Jaksic, Mark Jennings, Erik Johnson, Haruki Karube, David Kizirian, Ken Krysko, Kriton Kunz, Skip Lazell, Tim Low, Ann Marsteller, Roy McDiarmid, John Measey, Jesus Mellado, Paul Moler, Ron Nussbaum, Kimiko Okabe, Isamu Okochi, Hidetoshi Ota, Gad Perry, Robert Powell, Edoardo Razzetti, Robert Reed, Constance Rinaldo, Gordon Rodda, Martha Rosen, Phil Rosen, Pete Savarie, Riccardo Scalera, Patrick Schembri, Greg Schneider, Brad Shaffer, Glenn Shea, Dawn Skala, John Slapcinsky, Pritpal Soorae, Gill Sparrow, Thomas Ulber, Mark Wilkinson, Lori Williams, Julie Wycherley, and George Zug will all be residing in ethereal splendor upon relinquish- ing this mortal realm. In this vein, the choicest perquisites will be reserved for Aaron Bauer, Ron Crombie,

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