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Scientific Bases for the Preservation of the Hawaiian Crow SCIENTIFIC BASES FOR THE PRESERVATION OF THE HAWAIIAN CROW Committee on the Scientific Bases for the Preservation of the Hawaiian Crow Board on Biology Commission on Life Sciences National Research Council NATIONAL ACADEMY PRESS Washington, D.C. 1992
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Scientific Bases for the Preservation of the Hawaiian Crow National Academy Press 2101 Constitution Avenue, N.W. Washington, D.C. 20418 NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance. This report has been reviewed by a group other than the authors according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. This study by the Board on Biology was supported by the Department of the Interior, U.S. Fish and Wildlife Service under grant number 14-16-0001-91578. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the views of the U.S. Fish and Wildlife Service. Library of Congress Catalog Card No. 92-60711 International Standard Book Number 0-309-04775-7 Additional copies of this report are available from: National Academy Press 2101 Constitution Avenue, N.W. Washington, D.C. 20418 S-607 Copyright 1992 by the National Academy of Sciences Printed in the United States of America
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Scientific Bases for the Preservation of the Hawaiian Crow COMMITTEE ON THE SCIENTIFIC BASES FOR THE PRESERVATION OF THE HAWAIIAN CROW W. Donald Duckworth (Chairman), President and Director, Bishop Museum, Honolulu, HI Tom J. Cade, The Peregrine Fund, Boise, ID Hampton L. Carson, University of Hawai'i, Honolulu, HI Scott Derrickson, National Zoological Park, Front Royal, VA John Fitzpatrick, Archbold Biological Station, Lake Placid, FL Frances C. James, Florida State University, Tallahassee, FL Special Advisors Cynthia Kuehler, Zoological Society of San Diego, San Diego, CA Stuart Pimm, University of Tennessee, Knoxville, TN National Research Council Staff Donna M. Gerardi, Study Director Norman Grossblatt, Editor Scott Olson, Project Assistant Mary Kay Porter, Project Assistant
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Scientific Bases for the Preservation of the Hawaiian Crow BOARD ON BIOLOGY Harold E. Varmus (Chairman), University of California, San Francisco, CA Ananda M. Chakrabarty, University of Illinois, Chicago, IL Michael T. Clegg, University of California, Riverside, CA Richard E. Dickerson, University of California, Los Angeles, CA Richard E. Lenski, Michigan State University, East Lansing, MI Barbara J. Mazur, E.I. du Pont de Nemours & Co., Wilmington, DE Harold J. Morowitz, George Mason University, Fairfax, VA Daniel E. Morse, University of California, Santa Barbara, CA Philip Needleman, Monsanto Company, St. Louis, MO Mary Lou Pardue, Massachusetts Institute of Technology, Cambridge, MA David D. Sabatini, New York University, New York, NY Michael E. Soulé, University of California, Santa Cruz, CA Malcolm S. Steinberg, Princeton University, Princeton, NJ David B. Wake, University of California, Berkeley, CA Daniel I. C. Wang, Massachusetts Institute of Technology, Cambridge, MA Bruce M. Alberts (ex officio), University of California, San Francisco, CA National Research Council Staff Oskar R. Zaborsky, Director
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Scientific Bases for the Preservation of the Hawaiian Crow COMMISSION ON LIFE SCIENCES Bruce M. Alberts (Chairman), University of California, San Francisco, CA Bruce N. Ames, University of California, Berkeley, CA J. Michael Bishop, University of California, San Francisco, CA Michael T. Clegg, University of California, Riverside, CA Glenn A. Crosby, Washington State University, Pullman, WA Leroy E. Hood, California Institute of Technology, Pasadena, CA Donald F. Hornig, Harvard School of Public Health, Boston, MA Marian E. Koshland, University of California, Berkeley, CA Richard E. Lenski, Michigan State University, East Lansing, MI Steven P. Pakes, Southwestern Medical Center at Dallas, TX Emil A. Pfitzer, Hoffmann-LaRoche, Inc., Nutley, NJ Thomas D. Pollard, Johns Hopkins Medical School, Baltimore, MD Joseph E. Rall, National Institutes of Health, Bethesda, MD Richard D. Remington, University of Iowa, Iowa City, IA Paul G. Risser, University of New Mexico, Albuquerque, NM Harold M. Schmeck, Jr., Armonk, NY Richard B. Setlow, Brookhaven National Laboratory, Upton, NY Carla J. Shatz, University of California, Berkeley, CA Torsten N. Wiesel, Rockefeller University, New York, NY National Research Council Staff John E. Burris, Executive Director
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Scientific Bases for the Preservation of the Hawaiian Crow The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Frank Press is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. Robert M. White is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an advisor to the federal government and, upon its own initiative, to identify issues of medical care, research and education. Dr. Kenneth Shine is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy's purposes of furthering knowledge and of advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Frank Press and Dr. Robert M. White are chairman and vice chairman, respectively, of the National Research Council.
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Scientific Bases for the Preservation of the Hawaiian Crow PREFACE Much has been written about the unique and fragile environment of the state of Hawai'i. Formed by up-welling lava from the ocean floor, the Hawaiian archipelago is the world's most isolated island group, located some 4,000 km from the nearest continental land mass and 3,000 km north of the Marquesas Islands. The islands of Hawai'i range from sea level to over 4,000 m in elevation and receive an annual precipitation ranging from 200 mm to over 10,000 mm. Together, the isolation and diverse physiography of the islands influenced the evolution of a unique biota characterized by low phylogenetic diversity, high endemism, and spectacular adaptive radiations. Many groups of organisms—such as the silverswords (Asteraceae), lobeliads (Lobeliaceae), land snails (Achatinellidae, Amastridae, and others), pomace flies (Drosophilidae), and Hawaiian honeycreepers (Drepanidinae)—radiated from single ancestral populations into diverse assemblages of closely related species occupying a broad range of habitats. The extraordinary array of unique life forms on the Hawaiian archipelago that evolved over millions of years has declined at an ever-increasing rate since the arrival of humans and their intentional and accidental fellow travelers—exotic plants and animals—and today Hawai'i has the distinction of being the extinction capital of the world. Relatively intact native ecosystems have generally survived only at higher elevations, and many extant species now occupy only small remnant portions of their former ranges. Hawai'i consists of only 0.02% of the land area of the United States, but it has sustained nearly 75% of the nation's documented plant and animal extinctions, and native Hawaiian species are a substantial proportion of the species included on the U.S. list of Endangered and Threatened Wildlife and Plants1 Against that tapestry of severe habitat loss and loss of biological diversity, the efforts to save a single species, such as the Hawaiian Crow (Corvus hawaiiensis), or 'Alala, might seem to have little importance. However, single-species conservation efforts can be justified on moral, ethical, legal, economic, and scientific grounds, and it is especially important to recognize that programs to save single "indicator species" can provide a foundation for broader conservation and education initiatives. Research, habitat restoration, and educational efforts undertaken for the recovery of a single endangered species clearly can benefit a wide range of species and habitats if properly designed and effectively implemented. 1 U.S. Fish and Wildlife Service. 1991. Endangered and Threatened Wildlife and Plants. Title 50 17.11 and 17.12, July 15, 1991. Washington, D.C. : U.S. Fish and Wildlife Service, 37 pp.
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Scientific Bases for the Preservation of the Hawaiian Crow In response to a request from the U.S. Fish and Wildlife Service, the National Research Council's Board on Biology established the Committee on the Scientific Bases for the Preservation of the Hawaiian Crow ('Alala) in September 1991. Its task was to review the existing data pertaining to the 'Alala while focusing on several scientific issues: "Assess to the extent possible the causes of population trends of the 'Alala in the wild; "Assess to the extent possible the causes of population trends of the 'Alala in the captive population; "Evaluate options for action to maintain or increase numbers of the 'Alala in both the captive and wild populations; "Estimate the minimum viable population for survival of this species; and "Determine the advisability of adding genetic stock from the wild flock to the captive flock. If it is advisable, the 'form' in which this genetic material should be taken will be specified: e.g., eggs, fledglings, juvenile birds, or adults." Current options for recovery of the 'Alala vary; they range from bringing all birds into a captive propagation program to leaving the wild population undisturbed. From the assembled data and their evaluation, the committee has developed a set of recommendations designed to assist interested parties in working effectively to aid the recovery of the 'Alala. The committee held three meetings: two in Hawai'i (Honolulu, October 1991; Captain Cook, January 1992) and one at the Arnold and Mabel Beckman Center, Irvine, California (December, 1991). In addition, a subcommittee meeting was held at the Beckman Center (February 24–25, 1992). The committee collected and reviewed data on the 'Alala from biologists in federal and state agencies, other scientists and individuals. It visited the Olinda captive-breeding facility on the island of Maui. We are especially grateful to the owners and personnel of the McCandless Ranch on the island of Hawai'i for hosting the committee on a 2-day fact-finding trip on their property. The opportunity for the committee members in attendance to observe the 'Alala flock in nature was invaluable to the development of this report. Many persons assisted the committee in preparing this report, and we are grateful to them. The committee is especially indebted to those who submitted information for its review: Carolee Caffrey, University of California, Los Angeles Robert Fleischer, National Zoological Park Patricia Rabenold, Ohio State University Cheryl Tarr, Pennsylvania State University Special thanks are also due to the following persons, who were guests at committee meetings and participated in our discussions:
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Scientific Bases for the Preservation of the Hawaiian Crow In Honolulu Carter Atkinson, USFWS Michael Buck, Hawai'i DLNR Paul Conry, Hawai'i DLNR Reggie David, Hawai'i Audubon Society John Engbring, USFWS Jon Giffin, Hawai'i DLNR James Jacobi, USFWS Dana Kokubun, National Audubon Society Barbara Lee, Alala Foundation Robert Pyle, Bishop Museum and Hawai'i Audubon Society Karen Rosa, USFWS Nohea Santimer, Alala Foundation Charles Shockey, U.S. Department of Justice Peter Simmons, McCandless Properties Robert Smith, USFWS Paul Spaulding, III, Sierra Club Legal Defense Fund Carole Terry, Hawai'i DLNR Ronald Walker, Hawai'i DLNR Moani Zablan, Alala Foundation On Maui, Olinda Captive Breeding Facility Renate Gassman-Duvall, former contract veterinarian with Hawai'i DNLR Fern Duvall, Hawai'i DNLR Judy Pangelinan Subaitis, Hawai'i DNLR Wayne Taka, Hawai'i DNLR On Hawai'i Captain Cook and McCandless Ranch Paul Banko, USFWS Andrew Berger, University of Hawai'i Paul Breese, Honolulu Zoo John Phillips, Professor Emeritus, Stanford University Cynthia Salley, McCandless Ranch Nicholas Santimer, McCandless Ranch Nohea Santimer, McCandless Ranch Peter Simmons, McCandless Ranch Throughout the course of its deliberations, the committee was careful to maintain a steady focus on the scientific evidence available concerning the 'Alala and the implications of that evidence in relation to present and future efforts for recovery. Aware of past controversy and current disputes over recovery plans and techniques, which are the responsibilities of state and federal agencies and individuals, the committee assiduously adhered to its primary task. In this
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Scientific Bases for the Preservation of the Hawaiian Crow regard, the committee is grateful for the understanding and support of all parties associated with the study. The value of this approach, coupled with the considerable talent and experience of the committee members, is evidenced by the information and results described in the report. Finally, the committee wishes to acknowledge with gratitude and admiration the vital role played by the National Research Council staff in all aspects of the project. The dedicated professionalism of NRC study director Donna Gerardi facilitated and expedited the committee's activities throughout the study. In addition, Alvin Lazen and Norman Grossblatt added considerable experience and effort to the endeavor. W. Donald Duckworth, Chairman Committee on the Scientific Bases for the Preservation of the Hawaiian Crow May 1992
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Scientific Bases for the Preservation of the Hawaiian Crow CONTENTS EXECUTIVE SUMMARY 1 The Wild Population of 'Alala, 1 Avoiding Extinction, 2 The Captive Population of 'Alala, 4 Genetic Considerations, 6 Options for Management of the 'Alala, 7 1 INTRODUCTION 10 2 HISTORY OF THE WILD POPULATION AND CAUSES OF ITS DECLINE 12 Past and Present Distribution of the Wild Population, 12 The Geological Setting, 14 Geographic Distribution of the 'Alala, 16 Assessment of Extrinsic Causes of the Decline in the Population, 19 Habitat and Food, 19 Predators, 23 Diseases and Parasites, 24 Estimates of Population Viability and Time to Extinction, 26 Approaches, 26 Demographic Analyses, 27 Times to Extinction of Corvids on Islands, 40 3 GENETIC CONSIDERATIONS 45 4 CAPTIVE BREEDING OF THE 'ALALA 50 Origins and Facilities of the 'Alala Captive-Breeding Program, 51 Demographics and Genetics, 53 Inbreeding Depression, 59 Animal Husbandry and Management, 62 Staffing and Administration, 67 5 RELEVANT PRECEDENTS IN ENDANGERED SPECIES PRESERVATION 68 California Condor, 73 Magpie Robin, 74 Lord Howe Island Woodhen, 75 Takahe, 75 Kakapo, 75
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Scientific Bases for the Preservation of the Hawaiian Crow Chatham Island Black Robin, 76 Mauritius Kestrel, 76 Conclusions, 77 6 OPTIONS FOR MANAGEMENT OF THE 'ALALA 79 Option 1. Passive Management (Protection) of Wild Population, 79 Option 2. Removal of All Birds to Captivity, 84 Option 3. Translocation of All Wild Birds to Another Location in the Wild, 85 Option 4. Removal of Eggs from Wild Population for Artificial Incubation, 86 Option 5. Removal of Nestlings from Wild Population, 87 Option 6. Fostering as a Method of Release, 87 Option 7. Hacking and Other ''Soft" Methods of Release, 88 Option 8. Exchange of Captive and Wild Crows, 89 Conclusions, 89 7 FINDINGS AND RECOMMENDATIONS 90 The Wild Population, 90 Findings, 90 Maintaining a Wild Population, 91 Recovery Team, 92 Land Management, 92 Habitat preservation, 93 Cattle ranching, 94 Predator control, 95 Management of the Wild Population, 96 Additional Research, 97 Numbers, 97 Habitat, 97 Foraging behavior, 98 Physiology and disease, 99 Social behavior, 99 Demography, 100 The Captive Population, 100 Findings, 100 The Captive-Breeding Facility, 101 Husbandry in the Captive-Breeding Program, 102 Data, 103 General data, 103 Specific data, 103 Adults, 104 Chicks, 104 Eggs, 105 Nutrition, 105 Equipment at the Captive-Breeding Facility, 105 Personnel and Training, 105 Genetics of the Wild and Captive Populations, 106 Findings, 107 References 108 Appendix A 131 Appendix B 134 Biographical Statements 136