http://researchcommons.waikato.ac.nz/ Research Commons at the University of Waikato Copyright Statement: The digital copy of this thesis is protected by the Copyright Act 1994 (New Zealand). The thesis may be consulted by you, provided you comply with the provisions of the Act and the following conditions of use: Any use you make of these documents or images must be for research or private study purposes only, and you may not make them available to any other person. Authors control the copyright of their thesis. You will recognise the author’s right to be identified as the author of the thesis, and due acknowledgement will be made to the author where appropriate. You will obtain the author’s permission before publishing any material from the thesis. Sequencing the New Zealand dawn chorus: can song playback alter the timing of song initiation? A thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Biological Sciences at The University of Waikato by MARK MACDOUGALL 2017 Abstract The dawn chorus of songbirds is a behavioural phenomenon occurring prior to sunrise; birds of many different species sing simultaneously at rapid rates. Avian physiology, social behaviours and local environment all influence the onset of dawn song. The influence of social cues on dawn chorus singing is poorly delineated relative to the effect of environmental or physiological factors; in particular, our knowledge of the role of heterospecific cues is limited. In this study, I aimed to determine if New Zealand songbirds would chorus in a distinct order, like those seen in other countries. I investigated whether the timing of song onset relative to sunrise would change as the breeding season progressed. I also assessed if conspecific and heterospecific acoustic cues influence a species’ start time. Finally, I explored the influence of acoustic cues from an early singer, the Tui (Prosthemadera novaeseelandiae) and a late singer, the Riroriro (Grey Warbler; Gerygone igata) on start time. I recorded the dawn chorus at nine sites at the Maungatautari reserve between September and November 2016, using arrays of time- synchronised autonomous recording devices. I broadcast different playback stimuli at three arrays per morning; an early singer, a late singer, and noise. My results suggest that New Zealand dawn choruses follow an order and that the timing of chorus start time changes over time as the breeding season progresses. Tui began singing earliest, and their start time shifted much earlier as the breeding season progressed. Most species joined the chorus in a highly interchangeable order within the same 12 minute window, while Pōpokatea (Whitehead; Mohoua albicilla) i sang last. Start time was not found to shift in response to any playback stimuli for any species. The onset of Tui or Riroriro song is unlikely to be used as a cue by either con- or heterospecific neighbours to initiate their own dawn song. ii Acknowledgements First, I’d like to thank my supervisor, Joe Waas for his expert advice, endless support and patience. I could not have asked for a more knowledgeable, supportive and kind supervisor. I’d also like to thank my co-supervisor Jenn Foote, for her guidance and sharing her unparalleled knowledge of the dawn chorus. In particular, I’d like to thank her for bringing the field equipment all the way from Canada and instructing me on the fieldwork component, this project would not have been possible without her generosity and expertise. Many thanks to everyone at Sanctuary Mountain Maungatautari; to the trust for granting me use of such an ideal location for my study, and to the employees and volunteers for all their assistance and keen interest in the project. I’d also like to thank John Innes whose advice and assistance was invaluable in getting the project off the ground. Much appreciation also goes to Bruce Patty for his technical support and assistance in the field, and for being there every time I fell on my rear thanks to a tangle of supplejack. Thanks also go out to Ray Littler and Conrad Pilditch, for their assistance in conducting the statistical analyses. I’d also like to thank Kris Taipeti for laying the groundwork for this study. A big, big thanks to Mum and Dad for always unconditionally supporting me in any way they could, and for willingly being my minions out in the field when no-one else was able to. iii And finally, I’d like to thank the birds for what was nothing less than a stellar performance. Here’s to many bigger and bolder ones in years to come. iv Table of Contents Abstract ........................................................................................................ i Acknowledgements ..................................................................................... ii Table of Contents ....................................................................................... iii List of Figures ............................................................................................. v List of Tables.............................................................................................. vi Chapter 1: General Introduction ................................................................. 1 1.1 The dawn chorus ............................................................................. 1 1.2 Intrinsic factors ................................................................................. 2 1.3 Environmental factors ...................................................................... 3 1.4 Social factors ................................................................................... 4 1.5 The New Zealand Dawn Chorus ...................................................... 7 1.6 Aims ................................................................................................. 9 1.7 Thesis structure ............................................................................... 9 Chapter 2: Observational study of dawn chorus timing in New Zealand songbirds ......................................................................... 11 2.1 Introduction .................................................................................... 11 2.2 Methods ......................................................................................... 16 2.2.1 Study site and recording methods ........................................... 16 2.2.2 Protocol for data collection ...................................................... 20 2.2.3 Analysis ................................................................................... 21 2.3 Results ........................................................................................... 22 2.4 Discussion ..................................................................................... 24 Chapter 3: Experimental manipulation of dawn chorus start time through song playback .................................................................. 33 3.1 Introduction .................................................................................... 33 v 3.2 Method ........................................................................................... 37 3.2.1 Study site and recording methods ........................................... 37 3.2.2 Experimental design ................................................................ 39 3.2.3 Protocol for data collection ...................................................... 41 3.2.4 Analysis ................................................................................... 43 3.2.5 Ethical note ............................................................................. 44 3.3 Results ........................................................................................... 44 3.4 Discussion ..................................................................................... 47 Chapter 4: Conclusions and Recommendations ...................................... 54 4.1 Conclusions ................................................................................... 54 4.2 Recommendations ......................................................................... 58 References............................................................................................... 62 Appendix .................................................................................................. 69 vi List of Figures Figure 1: Map of Maungatautari reserve, with nine recording sites marked using red circles (Source: Google maps) ................... 18 Figure 2: The recording setup at each sampling station .......................... 19 Figure 3: Start times in minutes before sunrise for each species, with standard errors shown. Start times for species that do not share letters were found to be significantly different in the Tukey Pairwise comparisons. ................................................. 23 Figure 4: Linear regression from the linear model showing start time for each species against date (in days from the start of study) ...................................................................................... 23 Figure 5: The playback speaker (centre) and surrounding recorders at each sampling station ......................................................... 38 Figure 6: Spectrogram of a segment of Tui playback (a) compared with the noise control derived from Tui song (b) ..................... 40 Figure 7: Spectrogram of Riroriro playback (a) with the noise control derived from it (b). ................................................................... 40 Figure 8: Mean Tui start times