Distribution and calling phenology of generalist frog species along a climate gradient Amelia Walcott A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy Charles Sturt University Faculty of Science School of Environmental Sciences Albury, NSW 2640 Australia January 2017 i ii iii iv TABLE OF CONTENTS List of Figures ......................................................................................................................................... x List of Tables....................................................................................................................................... xiii List of Plates ........................................................................................................................................ xiv Certificate of Authorship ................................................................................................................ xv Acknowledgements ......................................................................................................................... xvii Abstract ................................................................................................................................................ xix Chapter 1 General introduction: Environmental drivers of amphibian distribution and resource use in modified temperate ecosystems ........................................................... 1 1.1 Wetland and amphibian decline ........................................................................................ 1 1.2 Frog occupancy and breeding patterns .......................................................................... 2 1.3 Hydrological modification .................................................................................................... 3 1.4 Climate change implications for frogs ............................................................................. 5 1.5 This research ............................................................................................................................. 8 1.6 Comments on thesis structure ........................................................................................... 9 Chapter 2 Study area description: environmental context of the mid to upper Lachlan ................................................................................................................................................... 11 2.1 Introduction ............................................................................................................................. 11 2.2 Climate ....................................................................................................................................... 12 2.2.1 Temperature & rainfall during this study............................................................ 13 2.3 Land use .................................................................................................................................... 14 2.4 Habitat modification ............................................................................................................. 16 2.5 Geomorphology ...................................................................................................................... 16 2.6 Fluvial characteristics .......................................................................................................... 18 2.7 Soils ............................................................................................................................................. 18 2.8 Vegetation................................................................................................................................. 19 v 2.9 Regulation of the Lachlan River ...................................................................................... 20 2.10 Climate variability, water governance & climate change ................................... 21 Chapter 3 Broad scale patterns & detectability of frog communities in the mid to upper Lachlan ..................................................................................................................................... 23 3.1 Introduction: Frog species in the Lachlan catchment ............................................. 23 3.2 Methods .................................................................................................................................... 24 3.2.1 Site selection strategy ................................................................................................. 24 3.2.2 Overview of the selected sites ................................................................................. 25 3.2.3 Survey design ................................................................................................................. 26 3.2.4 Field survey techniques ............................................................................................. 26 3.2.5 Frog surveys ................................................................................................................... 28 3.3 Data analysis ........................................................................................................................... 29 3.3.1 Detection probability .................................................................................................. 29 3.3.2 Atlas of NSW Wildlife .................................................................................................. 30 3.4 Results ....................................................................................................................................... 30 3.4.1 General distribution of frog species ...................................................................... 30 3.4.2 Comparison with Atlas data ..................................................................................... 31 3.5 Discussion ............................................................................................................................... 17 3.5.1 General patterns of occupancy ................................................................................ 17 3.5.2 Potentially false positive Atlas records ................................................................ 18 3.5.3 Non-detection of heavy rain responders ............................................................. 19 3.5.4 Rarely encountered species ...................................................................................... 19 3.5.5 Endangered, previously sympatric species ........................................................ 19 3.5.6 Unclassified species ..................................................................................................... 21 3.5.7 Species detectability .................................................................................................... 22 3.5.8 Other studies .................................................................................................................. 23 3.6 Conclusion................................................................................................................................ 26 vi Chapter 4 Local-scale habitat characteristics predict frog occupancy in the mid to upper Lachlan ..................................................................................................................................... 27 4.1 Introduction ............................................................................................................................. 27 4.1.1 Local waterbody-scale habitat factors .................................................................. 28 4.1.2 Landscape-scale habitat factors .............................................................................. 31 4.1.3 This study ......................................................................................................................... 32 4.2 Methods ..................................................................................................................................... 32 4.2.1 Environmental variables ............................................................................................ 32 4.2.2 Data reduction ................................................................................................................ 33 4.2.3 Statistical analysis ......................................................................................................... 36 4.3 Results....................................................................................................................................... 38 4.3.1 Model selection .............................................................................................................. 38 4.3.2 Species habitat associations ...................................................................................... 39 4.4 Discussion ................................................................................................................................. 49 4.4.1 Site climate history ....................................................................................................... 49 4.4.2 Vegetation ........................................................................................................................ 50 4.4.3 Water quality .................................................................................................................. 51 4.4.4 Grazing intensity ........................................................................................................... 51 4.4.5 Landscape connectivity .............................................................................................