Vertical Stratification of Insectivorous Bats (Microchiroptera) in Harvested
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University of Wollongong Research Online University of Wollongong Thesis Collection University of Wollongong Thesis Collections 2012 Vertical stratification of insectivorous bats (Microchiroptera) in harvested forests: assessing the role of structural clutter in shaping patterns of flight activity Maria Dawn Adams University of Wollongong Recommended Citation Adams, Maria Dawn, Vertical stratification of insectivorous bats (Microchiroptera) in harvested forests: assessing the role of structural clutter in shaping patterns of flight activity, Doctor of Philosophy thesis, School of Biological Sciences, University of Wollongong, 2012. http://ro.uow.edu.au/theses/3702 Research Online is the open access institutional repository for the University of Wollongong. For further information contact the UOW Library: [email protected] Vertical stratification of insectivorous bats (Microchiroptera) in harvested forests: assessing the role of structural clutter in shaping patterns of flight activity A thesis submitted in partial fulfilment of the requirements for the award of the degree of Doctor of Philosophy from the University of Wollongong by Maria Dawn Adams B. Env. Sc. (Hons.) School of Biological Sciences 2012 Thesis Certification I, Maria D. Adams, declare that this thesis, submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy, in the School of Biological Sciences, University of Wollongong, is wholly my own work unless otherwise referenced or acknowledged. The co-authors of any publications emanating from the thesis to date acted in the role of PhD supervisor. Dr Dave Britton contributed substantively to my insect work (Chapter 4) by prompting my research thoughts on moth audition, as well as identifying the macromoth families and their eared status. The document has not been submitted for qualification at any other academic institution. Maria D. Adams 2012 Contents Table of Contents Abstract .............................................................................................................. xv Acknowledgements ....................................................................................................... xiii Chapter 1. General Introduction .................................................................................. 1 1.1 Overview of the management of native vegetation ....................................... 1 1.2 Impacts of logging on forest structure and wildlife habitat ......................... 3 1.3 Wildlife management practices in logged forests in New South Wales ...... 5 1.4 Potential impacts of logging on forest bats .................................................... 7 1.5 Methods of assessing structural clutter effects for bats: benefits and drawbacks ....................................................................................................... 10 1.5.1 Acoustic sampling and trapping ........................................................... 10 1.5.2 Tracking bats ........................................................................................ 11 1.5.3 Experiments .......................................................................................... 13 1.5.4 Multiple approaches to bat-clutter assessment and justification for my methods ................................................................................................. 13 1.6 Some other methodological issues in bat research ...................................... 14 1.7 Project aims .................................................................................................... 15 1.8 Outline of chapters ......................................................................................... 16 1.9 How to read this thesis ................................................................................... 17 Chapter 2. Vegetation structure influences the vertical stratification of open- and edge-space aerial foraging bats in harvested forests .............................. 19 2.1 Introduction .................................................................................................... 19 2.2 Methods ........................................................................................................... 22 2.2.1 Study site description ............................................................................ 22 2.2.2 Bat and insect sampling ........................................................................ 23 2.2.3 Vegetation structure .............................................................................. 29 2.2.4 Statistical analysis ................................................................................. 30 2.3 Results ............................................................................................................. 32 2.3.1 Effects of logging history, stratum and time on bat activity – forest only ....................................................................................................... 32 i Contents 2.3.2 Effects of logging history, stratum and location on bat activity – evening only ......................................................................................... 35 2.3.3 Feeding buzzes for all bats and flight activity of non-guild species .... 38 2.3.4 Insect abundance................................................................................... 39 2.3.5 Vegetation structure .............................................................................. 40 2.3.6 Vegetation openness and insect abundance effects on bat activity ...... 41 2.4 Discussion........................................................................................................ 42 2.4.1 Vertical stratification of bats ................................................................ 42 2.4.2 Effects of vegetation structure on bat activity ...................................... 43 2.4.3 Other potential influences on bat activity ............................................. 46 2.4.4 Management implications and future research ..................................... 47 Chapter 3. A preliminary assessment of the impact of forest thinning on bat activity: towards improved clutter-based hypotheses ........................... 49 3.1 Introduction .................................................................................................... 49 3.2 Methods ........................................................................................................... 52 3.2.1 Study site description ........................................................................... 52 3.2.2 Bat and insect sampling ........................................................................ 52 3.2.3 Vegetation structure .............................................................................. 55 3.2.4 Statistical analysis ................................................................................ 55 3.3 Results ............................................................................................................. 57 3.3.1 Bats ....................................................................................................... 57 3.3.2 Vegetation ............................................................................................. 60 3.3.3 Bat activity and insect abundance ........................................................ 63 3.4 Discussion........................................................................................................ 65 3.4.1 High variability among and within sites ............................................... 65 3.4.2 Assessment of structural clutter with respect to bat activity ................ 66 3.4.3 Assessment of other forest thinning studies ......................................... 68 3.4.4 Measures of vegetation structural complexity for bats ......................... 72 3.4.5 Thinning, echolocation call guilds and clutter-tolerant species ........... 73 3.4.6 Potential influence of roost availability on bat activity ........................ 74 3.4.7 Future research and hypotheses ............................................................ 75 ii Contents Chapter 4. Spatial distribution of eared and earless macromoths in harvested forests: possible role of anti-predation strategies ................................... 77 4.1 Introduction .................................................................................................... 77 4.2 Methods ........................................................................................................... 80 4.2.1 Study site description ............................................................................ 80 4.2.2 Insect sampling ..................................................................................... 80 4.2.3 Statistical analysis ................................................................................. 82 4.3 Results ............................................................................................................. 84 4.3.1 Overview of insect, Lepidoptera and macromoth spatial patterns ....... 84 4.3.2 Macromoth totals, common taxa and stratum exclusivity .................... 85 4.3.3 Relative abundance of macromoths in insect samples ......................... 86 4.3.4 Abundance of macromoths and common taxa ..................................... 86 4.3.5 Taxonomic richness and diversity of macromoths ............................... 89 4.3.6 Macromoth assemblages ....................................................................... 91 4.4 Discussion .......................................................................................................