(ISBN: 0-943610-38-9) THE N ATIVE FOREST BIRDS OF GUAM BY J. MARK JENKINS D•vi\ion of AquatiC and Wi ld life Resources Department of Agriculture Government of Guam ORNITHOLOGICAL MONOGRAPHS :--10. 31 PUBLISHED BY TilE A \>If RIC' AN ORNITHOLOGISTS' UNION W-\SHINGTOJ\. D.C 1983 FRONTISPIECE. Above: Bridled White-eye (Zosterops conspicillata) from Truk, Caroline Islands, illustrating a typical white-eye posture. Photo by D.· Roberson. Below: Male Cardinal Honeyeater (Myzomela cardinalis safford!) illustrating the tendency to perch on exposed branches. Photo by H. D. Pratt. II THE NATIVE FOREST BIRDS OF GUAM ORNITHOLOGICAL MONOGRAPHS This series, published by the American Ornithologists' Union, was established for major papers too long for inclusion in the Union's journal, The Auk. Publi­ cation has been made possible through the generosity of the late Mrs. Carll Tucker and the Marcia Brady Tucker Foundation, Inc. Correspondence concerning manuscripts for publication in the series should be addressed to the Editor, Dr. Mercedes & Foster, USFWS, NHB-378, National\ Museum of Natural History, Washington, D.C. 20560. Copies of Ornithological Monographs may be ordered from the Assistant to the Treasurer of the AOU, Frank R. Moore, Department of Biology, University of Southern Mississippi, Southern Station Box 5018, Hattiesburg, Mississippi 39406. (See price list on back and inside back covers.) Ornithological Monographs No. 31, x + 61 pp. Editor of AOU Monographs, Mercedes S. Foster Special Reviewers for this issue, Murray D. Bruce, Turramurra, New South Wales; H. Douglas Pratt, Museum of Zoology, Louisiana State Uni­ versity, Baton Rouge Author, J. Mark Jenkins; present address: Ecological Sciences Section, De­ partment of Engineering Research, Pacific Gas and Electric Co., 3400 Crow Canyon Rd., San Ramon, California 94583 First received, 22 January 1982; revision completed, 30 March 1983; accepted 16 April 1983. Issued 9 December 1983. Price $9.00 prepaid ($7.00 to AOU members) Library of Congress Catalogue Card Number 83-72897 Printed by the Allen Press, Inc., Lawrence, Kansas 66044 Copyright © by the American Ornithologists' Union, 1983 ISBN: 0-943610-38-9 iv THE NATIVE FOREST BIRDS OF GUAM BY J. MARK JENKINS Division of Aquatic and Wildlife Resources Department of Agriculture Government of Guam ORNITHOLOGICAL MONOGRAPHS NO. 31 PUBLISHED BY THE AMERICAN ORNITHOLOGISTS' UNION WASHINGTON, D.C. 1983 TABLE OF CONTENTS INTRODUCTION .................................................................................................................................................................. STUDY AREA .............................................................................................................................................................................. 1 METHODS......................................................................................................................................................................................... 3 RoADSIDE CouNTS ........................................................................................................................................................ 5 STATION COUNTS ····························································································································································· 6 DISTRIBUTION AND ABUNDANCE ................................................................................................................. 6 SPECIES ACCOUNTS ...................................................................................................................................................... 6 YELLOW BITTERN (JXOBRYCHUS SINENSIS) ..................................................................................... 6 WHITE-THROATED GROUND DOVE (GALL/COLUMBA XANTHONURA) ............... 9 MARIANA FRUIT DOVE (PTILINOPUS ROSEICAPILLA) ......................................................... 14 GRAY SWIFTLET (AERODRAMUS VANIKORENSIS BARTSCH!) .................................. 18 MICRONESIAN KINGFISHER (HALCYON C. CINNAMOMINA) ............................... 21 MARIANA CROW (CORVUS KUBARYI) ...................................................................................................... 25 GUAM FLYCATCHER (MYIAGRA FREYCINETI) ............................................................................... 33 RUFOUS FANTAIL (RHIPIDURA RUFIFRONS URANIAE) .......................................................... 36 MICRONESIAN STARLING (APLONIS OPACA GUAM!) ............................................................... 39 CARDINAL HONEYEATER (MYZOMELA CARD/NALlS SAFFORD!) ................................ 44 BRIDLED WHITE-EYE (ZOSTEROPS C. CONSPICILLATA) .... ................................................ 48 OTHER NATIVE SPECIES ........................................................................................................................................ 50 MIGRANT SPECIES ............................................................................................................................................. 51 NON-NATIVE SPECIES .......................................................................................................................................... 51 DISCUSSION .............................................................................................................................................................................. 51 POPULATION DECLINES ........................................................................ ··································································· 52 CONSERVATION AND MANAGEMENT ................................................................................................. 53 ACKNOWLEDGMENTS .............................................................................................................................. 54 SUMMARY ................................................................................................................................................................... 55 LITERATURE CITED .............................................. ............................................................................................. 55 APPENDIX I, THE BIRDS OF GUAM, STATUS AND ABUNDANCE ... 57 APPENDIX II, INDICES OF SPECIES ABUNDANCE ON GUAM 60 vii LIST OF FIGURES Frontispiece: Bridled White-eye (Zosterops conspicillata) and Cardinal Honey eater (Myzornela cardinalis saffordz)............................................................. n Figure 1. Map of the Mariana Islands........................................................................................................... 2 2. Locations of the 11 forest bird census stations and other localities mentioned in the text............................................................................................................................. 4 3. North, South, North-central, and Northwest Field roadside bird census routes....................................................................................................................................................... 5 4. Distribution and abundance of the Yellow Bittern on Guam, 1978-1979............................................................................................................................................................. 9 5. Male White-throated Ground Dove................................................................................... 10 6. Distribution and abundance of the White-throated Ground Dove on Guam, 1978-1979............................................................................................................................. 12 7. Mean number ofWhite-throated Ground Doves observed during roadside counts on the North and South Routes.............................................. 13 8. Mean number of White-throated Ground Doves observed during roadside counts on North, Northwest Field, and North-central Routes........................................................................................................................................................................ 14 9. Mean number of Mariana Fruit Doves observed during roadside counts on North, Northwest Field, and North-central Routes....... 16 10. Distribution and abundance of the Mariana Fruit Dove on Guam, 1978-1979............................................................................................................................................................. 17 11. Distribution and abundance of the Gray Swiftlet on Guam, 1978-1979............................................................................................................................................................. 20 12. Distribution and abundance of the Micronesian Kingfisher on Guam, 1978-1979...................................................................................................................................... 21 13. Mean number of Micronesian Kingfishers observed during road­ side counts on North, Northwest Field, and North-central Routes.......................................................................................................................................................................... 22 14. Distribution and abundance of the Mariana Crow on Guam, 1978-1979............................................................................................................................................................. 24 15. Mean number of Mariana Crows observed during roadside counts on