The noisy native: a miner menace? Noisy miner habitat preferences and influence on woodland bird species richness Sarah Chubb Submitted in partial fulfilment of the requirements for the degree of Bachelor of Science with Honours in the Fenner School of Environment and Society, Australian National University November 2011 ii Candidate's Declaration This thesis contains no material which has been accepted for the award of any other degree or diploma in any university. To the best of the author’s knowledge, it contains no material previously published or written by another person, except where due reference is made in the text. Sarah Constance Chubb Date Sarah Chubb The noisy native: a miner menace? iii Acknowledgements This project has let me immerse myself in a topic that I have been passionate about – and I have come out of it thoroughly inspired. My inspiration has largely come from the people who have supported and nurtured my learning experiences, without whom this project would not have been possible! To my supervisors, Chris McElhinny and Julian Reid, many thanks for all of your guidance and support over the past 9 months. You have helped me to shape my research, and thesis, and have provided me with the encouragement and enthusiasm that helped me to sustain my interest (and energy) throughout the year. Thank-you Chris, for being such a wonderful teacher over the past 3 years. You are an inspiration to me. Without the support and funding of the Cowra Woodland Birds Program, this project could not have happened. John and Madeline Rankin, Neale and Janeen Coutanche, Malcolm Fyfe, Maret Vesk and Rosemary Stapleton have been so encouraging and made me feel so welcome in Cowra. The success of this Program is owed to the efforts of the survey volunteers and the willingness of the landholders to let the CWBP survey on their property. The ANU has generously provided funding through the Action Trust scholarship. To my fieldwork partner, Isabela ‘old man’ Burgher, for the picturesque picnics, your love of driving and your singing. You have made many a long day in the field fun and enjoyable. Sam and Clair Johnson and Catherine Bennett have been enormously generous, providing us with not only a bed, but a home while Isabela and I were in the field. The Fenner School staff, particularly Matt Brookhouse, Field Services, the IT gurus and administration, has been tremendously supportive. Assistance from family and friends, especially my dad, in improving my thesis through hours of proof reading and discussions has been astounding. I am very grateful to mum, an amazing cook and enough of a sucker to get coerced into helping out with fieldwork. To my honours cohort, for the love, laughs, smiles, ciders, cakes and tea breaks. I couldn’t have chosen a better group of people to spend this year with. Thanks to the mothers of the honours room for the amazing food, and to those who kept it ‘manly’. Mark, thanks for your love and support over the past year, I’m looking forward to seeing you a bit more now! Sarah Chubb The noisy native: a miner menace? iv Abstract Through its aggressive, competitive behaviour, the noisy miner (Manorina melanocephala) may be excluding woodland birds from remnant vegetation. This process exacerbates declines in bird populations already threatened by landscape modification. The aims of this study were to understand how the noisy miner affects woodland bird species, and to quantify its habitat preferences to inform effective management strategies. These aims were addressed using the following research questions: 1. Does noisy miner presence and/or abundance affect bird species richness? - Which bird species are more susceptible to the effects of noisy miner invasion? - Is there a density threshold where their effect is more pronounced? 2. Is noisy miner abundance affected by landscape and/or patch-scale variables? - Which variables are the most powerful in explaining noisy miner abundance? This research was conducted in 2011 at 33 temperate box-gum woodland sites in the Cowra Shire of New South Wales, in conjunction with the Cowra Woodland Birds Program, which has collected bird data since 2002. These data were augmented by detailed landscape and patch scale habitat data as part of the current project. Noisy miner impacts on five different categories of bird species richness (Total birds, Woodland birds, Small woodland birds, Threatened and declining birds and Non-woodland birds) were analysed using correlation and analysis of variance with categorical values of noisy miner abundance. This was followed by a more detailed generalised linear model with a Poisson distribution and a log link function, using continuous values of noisy miner abundance. Habitat preferences of the noisy miner were identified using correlation analysis and analysis of variance, followed by a more detailed multivariate least squares regression model in which average noisy miner abundance, a continuous dependent variable, was modeled in terms of multiple habitat parameters. Results of this analysis suggest that noisy miners had a highly significant (p<0.0005) negative affect on all bird categories except non-woodland birds. Small woodland birds showed the most significant effects (p<0.0001), with highest species richness in sites where noisy miners were never present, moderate richness in low and moderate noisy miner sites and very low richness in high noisy miner sites. Generalised linear modelling indicated that the presence of just one noisy miner reduced small woodland bird species richness by 40%. In the Cowra region, it appears that persistent noisy miner presence at a site, even at very low levels, is a strong predictor of the richness of small woodland birds that will be present at that site. Noisy miner abundance responded negatively to both landscape and patch scale habitat variables. A multivariate least squares regression indicated that 50% of variance in noisy miner abundance could be explained using the parameters of patch area, Callitris regeneration and the density of hollow trees, all of which reduced noisy miner abundance. Individually, the Sarah Chubb The noisy native: a miner menace? v landscape variables of patch area and vegetation cover were the strongest predictors of noisy miner abundance. Patches greater than 30 ha in size or with more than 20% vegetation cover in the surrounding regions had lowest noisy miner abundance. Many of the findings in this study, are comparable with other studies in temperate woodlands of south eastern Australia, and can be used to inform management practices. These include: - Maintaining or increasing woody vegetation surrounding patches because low vegetation cover is associated with high noisy miner abundance. - Protecting sites with an intact understorey from modification and degradation. - Revegetation and restoration efforts in sites with naturally low Eucalyptus occurrence should avoid increasing eucalypt species density, as this may attract the noisy miner. Rather, species used in revegetation should be selected on a site- specific basis. - Directing revegetation and restoration activities at habitat features that deter patch utilisation by noisy miners, such as a dense understorey of Callitris or Eucalyptus regeneration. Many of these outcomes can be achieved through tree planting or appropriate grazing and fire regimes, indicating astute management at patch and landscape levels could assist in reversing further declines in the woodland bird communities of south eastern Australia; particularly those due to the aggressive behaviour of the noisy miner. Sarah Chubb The noisy native: a miner menace? vi Table of Contents Candidate's Declaration ..................................................................................................... ii Acknowledgements ............................................................................................................ iii Abstract .............................................................................................................................. iv Table of Contents ............................................................................................................... vi List of Figures ................................................................................................................ viii List of Tables ................................................................................................................. viii Chapter 1: Introduction ..................................................................................................... 2 1.1 Native invasive species ........................................................................................... 4 1.2 Woodland bird declines in south eastern Australia ................................................. 5 1.3 Research Aims ........................................................................................................ 5 1.4 Thesis Structure ....................................................................................................... 6 Chapter 2: Literature Review ............................................................................................ 8 2.1 Invasive species: the Australian perspective ........................................................... 8 2.2 The noisy miner ....................................................................................................... 9 2.3 How does the noisy miner affect woodland birds? ............................................... 10 2.3.1 Which birds are most