Department of Environmental Biology Diversity of butterflies and day-flying moths in urban habitat fragments, south-western Australia Matthew R. Williams This thesis is presented for the degree of Doctor of Philosophy of Curtin University of Technology February 2009 Table of Contents Statement of originality ......................................................................................... 5 Acknowledgements ................................................................................................ 6 Abstract ................................................................................................................. 7 Chapter 1 – General Introduction ......................................................................... 9 1.1 Habitat fragmentation ..................................................................................... 9 1.1.1 Ecological impacts of fragmentation......................................................... 9 1.1.1.1 Habitat reduction ......................................................................... 10 1.1.1.2 Habitat alteration ......................................................................... 10 1.1.1.3 Edge effects ................................................................................ 11 1.1.1.4 Connectivity between fragments and barrier effects ...................... 11 1.1.1.5 Habitat degradation ..................................................................... 11 1.1.1.6 New habitats ............................................................................... 12 1.1.1.7 Interactions ................................................................................. 12 1.1.1.8 Species responses ........................................................................ 13 1.1.2 Urban fragments .................................................................................... 14 1.2 Butterflies .................................................................................................... 15 1.2.1 Decline of butterflies ............................................................................. 15 1.2.1.1 World-wide ................................................................................. 16 1.2.1.2 Australia ..................................................................................... 16 1.2.1.3 Western Australia ........................................................................ 16 1.3 Methodology ................................................................................................ 17 1.3.1 Sampling methods ................................................................................. 17 1.3.2 Estimating occupancy, abundance and species richness ........................... 18 1.3.2.1 Detectability ................................................................................ 18 1.3.2.2 Occupancy .................................................................................. 19 1.3.2.3 Abundance .................................................................................. 20 1.3.2.4 Species richness .......................................................................... 20 1.3.2.5 Relationship between occupancy, detectability and abundance ...... 21 1.3.3 Comparison of sampling methods........................................................... 21 1.3.3.1 Introduction and aims .................................................................. 21 1.3.3.2 Methods ...................................................................................... 22 1.3.3.3 Results ........................................................................................ 22 1.3.3.4 Discussion ................................................................................... 27 1.3.3.5 Conclusion .................................................................................. 29 1.3.4 Modelling species presence, abundance and richness .............................. 30 1.3.4.1 The species–area relationship ....................................................... 31 1.3.4.2 Incorporating other covariates ...................................................... 31 1.3.4.3 Interactions between covariates .................................................... 31 1.4 Study species ............................................................................................... 32 1.5 Study area .................................................................................................... 36 1.6 Study objectives and thesis structure ............................................................. 37 1.6.1 Study objectives .................................................................................... 37 1.6.2 Thesis structure...................................................................................... 38 2 Chapter 2 – Assessing diversity of diurnal Lepidoptera in habitat fragments: testing the efficiency of strip transects ................................................................. 39 Abstract ............................................................................................................. 39 Introduction ....................................................................................................... 40 Methods............................................................................................................. 41 Results............................................................................................................... 44 Discussion ......................................................................................................... 53 Acknowledgments ............................................................................................. 55 References ......................................................................................................... 56 Chapter 3 – Butterflies and day-flying moths in a fragmented urban landscape, south-west Western Australia: patterns of species richness ................................ 62 Abstract ............................................................................................................. 62 Introduction ....................................................................................................... 63 Methods............................................................................................................. 65 Data analysis .................................................................................................. 69 Results............................................................................................................... 71 Discussion ......................................................................................................... 78 Acknowledgements ............................................................................................ 84 References ......................................................................................................... 85 Chapter 4 – Species–area functions revisited ...................................................... 91 Abstract ............................................................................................................. 91 Introduction ....................................................................................................... 93 The functional models of the species–area relationship........................................ 95 Including additional variables ............................................................................. 98 Fitting species–area functions ............................................................................. 99 Comparing species–area functions .................................................................... 101 An empirical comparison of species–area functions........................................... 103 Discussion ....................................................................................................... 107 Acknowledgements .......................................................................................... 110 References ....................................................................................................... 111 Appendix S1. Algebraic comparisons of alternative species–area functions........ 117 Appendix S2. Parameterization of species–area link functions ........................... 120 Appendix S3. Comparison of alternative species–area functions as models of the number of plant species in the British Isles ....................................................... 121 Appendix S4. Comparison of alternative models of the number of plant species in the British Isles ................................................................................................ 122 Appendix S5. Models of the number of plant species (S) in the British Isles, excluding Britain ............................................................................................. 123 Chapter 5 - Habitat resources determine distribution patterns and abundance of butterflies and day-flying moths in a fragmented urban landscape, south-west Western Australia .............................................................................................. 124 Abstract ........................................................................................................... 124 Introduction ..................................................................................................... 125 Methods........................................................................................................... 127 Study Area ..................................................................................................