Deakin University Access to Thesis. Elizabeth Lavzanian is the author of the thesis entitled: ‘Diet and habitat of the Powerful Owl (Ninox strenua) Living near Melbourne’. This thesis may be made available for consultation, loan and limited copying for the purpose of study and/or research in accordance with the Copyright Act 1968 [Australia]. This thesis was submitted for the degree of Master of Applied Science and is the result of the authors own research, except where otherwise acknowledged, and that the thesis in whole or part has not been submitted for an award including a higher degree to any other university or institution. This document has been processed by an optical character recognition program, thus there is a possibility of transcription errors. Diet and Habitat of the Powerful Owl (Ninox strenua) Living Near Melbourne. By Elizabeth Lavazanian Bachelor of Education (Secondary) - Environmental Studies Master of Applied Science report submitted as part of the requirements for the degree Master of Applied Science within the Faculty of Science and Technology, Deakin University. 30.9.1996 Thirtieth of September Nineteen Ninety Six iii Acknowledgments The completion of this thesis would not have been possible without the continuous help, support, patience and understanding I have received from my husband, family, colleagues, the staff at Deakin University and the Department of Conservation and Natural Resources. In particular, I would sincerely like to thank my supervisor Rob Wallis for his supervision guidance, constructive criticism and enthusiasm towards this product. I would like to thank Rob for always being available to offer his help. This final product would not have been possible without the generous advice and support he has given me throughout the past three years. I would like to express my appreciation to Alan Webster for providing me with the opportunity to undertake this project as a part of a wider investigation into the conservation of the Powerful Owl in the Warrandyte-Kinglake Nature Conservation Link. I would like to thank Alan for the endless number of hours he has spent collecting pellets over the past three years, his constructive criticism towards this project and the constructive comments towards this manuscript. I would also like to thank him for the use of his excellent photographs and slides. I would especially like to thank my husband Cohn who provided me with endless support, encouragement, patience and understanding. I would also like to thank him for his computer expertise and for accompanying me on my spotlight trips. I would like to extend my gratitude towards Roger Gaymer for all the patience and time he has spent showing me how to use the computer program Photoshop ®. I would also like to thank him for his advice on photographing the bones. iv I would like to thank Chris Lewis for accompanying me on the field trips and spotlight runs. I would also like to thank him for his computer and mapping expertise. I also appreciate the assistance of Philip Irwin for helping me interpret some of my results and for choosing the appropriate statistical tests to use in this project. I would like to thank Hans Brunner, Jenny Wilson and Richard Hammond who helped in the analysis of some of the pellets. I would also like to thank Raylene Cooke for her help and Andrea Burke for accompanying me on my field trips. I also appreciate the assistance of Dianne Simmons who helped me locate some of my study sites and identified some of the trees and shrubs on my field trips. For his advice and constructive criticism towards this project, I would like to thank Richard Loyn. Finally, for their generous help, support and friendship I would like to thank all the ASNRM staff. v Table of Contents Statement of Responsibility ii Acknowledgments iii List of Figures viii List of Tables List of Plates x Abstract xiii Summary xvi 1.0 INTRODUCTION 1 1.1 Historical Background 1 1.2 The Powerful Owl 3 1.2. 1 Description of the species 3 1.2.2 Conservation status 6 1.2.3 Distribution 7 1.2.4 Roosting and Nesting 9 1.3 Aims of the Study 11 2.0 METHODOLOGY 14 2.1 Part A Dietary Study- Site Locality and Description 14 2.2 Fauna 16 2.3 Flora 17 2.4 Methodology 18 2.4.1 Analysis of Skeletal Remains 19 2.4.2 Hair Analysis 19 2.5 Part B Habitat Study- Site Locality and Description 21 2.6 Methodology 23 vi 3.0 DIAGNOSTIC AID TO THE IDENTIFICATION OF POTENTIAL PREY SPECIES 26 3.1 Introduction 26 3.2 Identification of Guard Hairs 28 3.2.1 Hair Length 28 3.2.2 Bands of Colour 29 3.2.3 Medulla Structure 30 3.2.4 Cross Section 32 3.3 Diagnostic Features of Major Bones 35 3.3.1 Skull 35 3.3.2 Dentition 38 3.3.3 Limbs (Humerus I Femur) 43 3.3.4 Scapula and Pelvic Girdle 43 3.4 Age Class Determination in Possums 44 4.0 FOOD OF THE POWERFUL OWL 54 AT CHRISTMAS HILLS 4.1 Introduction 54 4.2 Food Categories 55 4.3 Seasonal Variation of Mammalian Prey in the diet 57 4.4 Age Classes of Common Ringtail Possums Prey 62 4.5 Previous Dietary Studies 65 4.6 Conclusion 67 5.0 HABITAT OF THE POWERFUL OWLS 68 5.1 Introduction 68 5.2 Habitat features 69 5.3 Habitat Management 81 5.3.1 Nest and Roost sites of the Powerful Owl 82 5.3.2 Management Recommendations 85 vii 6.0 CONCLUSIONS 86 References 88 Appendix 96 I. A list of native mammals found at One Tree Hill Reserve 97 (excluding bats) II. Pellet analysis data sheet 98 III. Diet of Powerful Owls (Ninox strenua) living near Melbourne, Victoria. 99 viii List of Figures 1. The distribution of the Powerful Owl in Australia 8 2. The distribution of the Powerful Owl in Victoria 8 3. Location of the Study site - One Tree Hill 15 4. Map of the Warrandyte-Kinglake Nature Conservation Link 22 5. Location of the study sites in Warrandyte-Kinglake Nature 25 Conservation Link 6. Profiles of representative primary guard hairs of the Common 28 Brushtail Possum, Common Ringtail Possum and Sugar Glider 7. Whole mount of a possum’s primary and secondary guard hair 30,31 8. Cross section of the primary guard hairs of the Common Brushtail 32,33,34 Possum, Common Ringtail Possum and Sugar Glider 9. Dorsal view of the skulls of the Common Brushtail Possum, 35,36,37 Common Ringtail Possum and Sugar Glider 10. Dentition of the Common Brushtail Possum, Common Ringtail 38,39,40,41 Possum arid Sugar Glider 11. Lower Jaw of the Common Brushtail Possum and Common Ringtail 42 Possum ix 12. Humerus of the Common Brushtail Possum Common Ringtail 46 Possum and Sugar Glider 13. Femur of the Common Brushtail Possum, Common Ringtail Possum 47 and Sugar Glider 14. Scapula of the Common Brushtail Possum Common Ringtail 48 Possum and Sugar Glider 15. Pelvic Girdle of the Common Brushtail Possum,, Common Ringtail 49 Possum and Sugar Glider 16. Humerus of the Common Brushtail Possum at three different ages 50 17. Humerus of the Common Ringtail Possum at two different ages 51 18. Dorsal view of the Common Brushtail Possum skull at three 52 different ages. 19. Lower Jaw dentition of the Common Brushtail Possum and Common 53 Ringtail Possum. 20. Number of pellets collected over the four seasons containing various 58 species of mammalian prey 21. Age classes of the Common Ringtail Possum prey detected in owl 63 pellets over the four seasons x 22. Records of sightings of the Powerful Owl and location of the study 76 sites in the Warrandyte-Kinglake Nature Conservation Link 23. Dendrogram 79 24. Roost and nest trees of the Powerful Owl 84 List of Tables 1. Dietary components in pellets collected over spring, summer, 55 autumn and winter. 2. Percentage of pellets collected over spring, summer, autumn and 57 winter containing various mammalian species. 3. Results of a chi-square test to assess the significance of any seasonal 61 difference in the occurrences of three species of mammalian prey in the Powerful Owls’ diet. 4. Age classes of possum prey over spring, summer, autumn and 62 winter. 5. Summarized results of the habitat study 77 6. Results of a correlation co-efficient test 78 xi List of Plates 1. The Powerful Owl (Ninox strenua). Photo: Alan Webster xvii 2. Pair of Powerful Owls roosting at Warrandyte State Park. 5 Photo: Alan Webster 3. Adult female with two owlets roosting in E. obliqua (roost 23) at 5 One Tree Hill. Photo: Alan Webster 4. Nest tree (E. obliqua) utilised by the Powerful Owl in 1991 at One 10 Tree Hill. Photo: Alan Webster 5. Juvenile Powerful Owl (at fledging stage approximately 12 weeks 13 old) roosting at One Tree Hill Reserve. Photo: Alan Webster 6. Sub-adult Powerful Owl holding a Common Ringtail Possum at One 59 Tree Hill Reserve. Photo: Alan Webster 7. Adult Powerful Owl holding a Common Brushtail Possum at 60 Warrandyte State Park. Photo: Alan Webster 8. A pellet containing Common Ringtail Possum remains teased out 64 onto a sheet of paper 9. A pellet containing Sugar Glider remains teased out onto a sheet of 64 paper 10. Category A Site 70 xii 11. Category B Site 70 12. Category C Site 71 13. Category D Site 71 14. Nest tree (E. obliqua) utilised by the Powerful Owl in 1995 at One 83 Tree Hill. Photo: Alan Webster xiii Abstract The diet of Powerful Owls (Ninox strenua) living at Christmas Hills, 35km north-east of Melbourne was examined by analysis of 686 regurgitated pellets collected over two years.