Effects of age on reproduction and chick rearing in bridled terns (Onychoprion anaethetus) at Penguin Island, Western Australia This thesis is presented for the degree of Doctor of Philosophy, Murdoch University Submitted by Aurélie Marie Thérèse Labbé BSc (Hons.) (Murdoch University, Western Australia) June 2017 Declaration I declare that this thesis is my own account of my research and contains as its main content work that has not previously been submitted for a degree at any tertiary education institution Aurélie Marie Thérèse Labbé i Table of Contents Table of contents Declaration ......................................................................................................................... i Abstract ............................................................................................................................ vi Acknowledgements ......................................................................................................... vii Overview of manuscripts ............................................................................................... viii List of Figures .................................................................................................................. ix List of Tables ................................................................................................................... xi 1. Introduction ................................................................................................................... 1 1.1 The ecological significance of seabirds .................................................................. 1 1.2 The tern family ........................................................................................................ 2 1.3 Bridled terns ............................................................................................................ 2 1.4 Particularities of oceanographic conditions in Western Australia and implications for bridled terns ............................................................................................................. 3 1.5 Bridled terns on Penguin Island .............................................................................. 6 1.6 Bridled terns as a case study ................................................................................... 6 1.7 Aims of the thesis .................................................................................................... 8 1.8 References ............................................................................................................... 9 2. Age effects on breeding in seabirds – a review .......................................................... 13 2.1 Abstract ................................................................................................................. 13 2.2 Introduction ........................................................................................................... 13 2.3 Materials and methods .......................................................................................... 15 2.4 Results ................................................................................................................... 16 2.4.1 Overview ........................................................................................................ 16 2.4.2 Assessing the effects of age on breeding performance .................................. 20 2.4.3 The constraint/restraint hypothesis ................................................................ 20 2.4.4 Studies of selective appearance/disappearance and breeding experience ...... 21 2.4.5 Reproductive effort ........................................................................................ 21 2.4.6 Reproductive senescence ............................................................................... 22 2.5 Discussion ............................................................................................................. 22 2.5.1 Processes involved in breeding performance related with age ...................... 22 2.5.1.1 Selective disappearance/appearance ........................................................ 22 2.5.1.2 Breeding experience ................................................................................. 23 2.5.1.3 Increased Reproductive Effort ................................................................. 24 2.5.1.4 Senescence ............................................................................................... 24 2.5.2 Further research.............................................................................................. 25 ii Table of Contents 2.6 Conclusion ............................................................................................................ 26 2.7 References ............................................................................................................. 26 3. Site description, general methods and baseline of the study ....................................... 31 3.1 Overview ............................................................................................................... 31 3.2 Site description: Penguin Island ............................................................................ 32 3.2.1 Geomorphology and currents surrounding Penguin Island ............................ 32 3.2.2 Flora on Penguin Island ................................................................................. 33 3.2.3 Fauna and tourism on Penguin Island ............................................................ 33 3.2.4 Black rats on Penguin Island .......................................................................... 34 3.3 Study site ............................................................................................................... 35 3.4 Artificial nest tubes ............................................................................................... 36 3.5 Natural nests selection........................................................................................... 41 3.6 Revegetation of the study area .............................................................................. 41 3.7 Capture and banding of bridled terns .................................................................... 42 3.8 Justifications .......................................................................................................... 43 3.9 Bridled tern age determination .............................................................................. 44 3.10 Sex determination of bridled terns ...................................................................... 45 3.11 Climatic and oceanic conditions ......................................................................... 46 3.12 Permits and licences ............................................................................................ 47 3.13 References ........................................................................................................... 48 4. Skin pentosidine does not correlate with age in a long-lived seabird ......................... 51 4.1 Abstract ................................................................................................................. 51 4.2 Introduction ........................................................................................................... 51 4.3 Materials and Methods .......................................................................................... 53 4.3.1 Trapping of birds ............................................................................................ 53 4.3.2 Skin sampling ................................................................................................. 53 4.3.3 Sample analysis .............................................................................................. 54 4.4 Results ................................................................................................................... 54 4.5 Discussion ............................................................................................................. 55 4.5.1 Pentosidine in bridled terns ............................................................................ 55 4.5.2 Low recapture rate of known-age individuals ................................................ 57 4.6 References ............................................................................................................. 57 5. Effects of age on the reproduction of a long-lived tropical seabird: the bridled tern . 60 5.1 Abstract ................................................................................................................. 60 5.2 Introduction ........................................................................................................... 60 iii Table of Contents 5.3 Methods ................................................................................................................. 63 5.3.1 Data collection ............................................................................................... 63 5.3.2 Cross-sectional analysis ................................................................................. 66 5.3.3 Longitudinal analysis ..................................................................................... 67 5.4 Results ................................................................................................................... 67 5.4.1 Overview ........................................................................................................ 67 5.4.2 Cross-sectional analysis