Does the presence of grevilleas and eucalypts in urban gardens influence the distribution and foraging ecology of Noisy Miners?
Lisa C. Ashley A C D , Richard E. Major B and Charlotte E. Taylor AA School of Biological Sciences, University of Sydney, NSW 2006, Australia.
B Terrestrial Ecology, Australian Museum, 6 College St, Sydney, NSW 2010, Australia.
C Present address: Faculty of Veterinary Science, University of Sydney, NSW 2006, Australia.
D Corresponding author. Email: l.ashley@usyd.edu.au
Emu 109(2) 135-142 https://doi.org/10.1071/MU07043
Submitted: 26 August 2007 Accepted: 27 February 2009 Published: 10 June 2009
Abstract
Noisy Miners have been described as a ‘reverse keystone’ species, aggressively excluding many bird species from an ever-increasing range of human-dominated landscapes. Understanding the factors influencing the distribution of Noisy Miners is therefore an important research priority. To determine whether a relationship exists between the distribution of Noisy Miners and the vegetation composition of suburban gardens, birds were surveyed according to a factorial design defined by the presence or absence of grevilleas and eucalypts. Contrary to popular expectation, there was no significant association between the abundance of Noisy Miners and the presence of hybrid grevilleas. However, there was a highly significant relationship between the abundance of Noisy Miners and the presence of eucalypts. Analysis of foraging time budgets showed that Noisy Miners consistently spent 25–30% of their foraging time feeding on grevilleas (only in sites in which they were present). Similar amounts of time were spent foraging in eucalypts or in flowering callistemons (when available), and the presence of grevilleas did not result in a reduction in overall commitments to foraging. Noisy Miners also spent substantial amounts of time foraging on open ground. This study does not support the notion that hybrid grevilleas have played a causal role in the spread of Noisy Miners across many suburban areas of eastern Australia. Our results are consistent with the hypothesis that it is the proliferation of lightly-treed open areas that favours the Noisy Miner.
Additional keyword: Manorina melanocephala.
Acknowledgements
We thank Wade Ashley and Marion Wadsworth for their help with fieldwork, Kate Ravich and Judy Christie for drumming up volunteers and conducting surveys, and the many volunteers that allowed the use of their private gardens. This research was conducted in partial fulfilment of an honours degree (L. C. Ashley) and with approval from the University of Sydney Human and Animal Ethics Committees (Animal ethics committee protocol number L04/10-2003/1/3820; Human ethics committee protocol number 7052). Funding for the research was provided by the University of Sydney and Birds in Backyards, a program of Birds Australia and the Australian Museum.
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