Detection and habitat use of the Rufous Bristlebird (Dasyornis broadbenti) in coastal heathland, in south-western Victoria, Australia
Ellen Mitchell A C and Barbara A. Wilson BA School of Life and Environmental Sciences, Deakin University, Geelong, Vic. 3217, Australia.
B Department of Environment and Conservation, 5 Dundebar Road, Wanneroo, WA 6065, Australia.
C Corresponding author. Email: ellen.mitchell@banyule.vic.gov.au
Emu 107(4) 327-334 https://doi.org/10.1071/MU06048
Submitted: 25 September 2006 Accepted: 8 November 2007 Published: 7 December 2007
Abstract
The Rufous Bristlebird (Dasyornis broadbenti) is a sedentary, ground-dwelling passerine of southern Australia, which is listed as nationally vulnerable, and as near-threatened (lower risk) in Victoria. The species inhabits a variety of vegetation, including shrub thickets in coastal gullies to heathlands on limestone cliffs. This study aimed to assess the size, distribution and habitat use of a population of the subspecies D. b. broadbenti at Portland in south-western Victoria. Monthly surveys (2002–03) were conducted on foot for 1 h after official sunrise and 1 h before official sunset, and presence of Bristlebirds recorded using vocalisations and sightings. Observations outside of the survey times were also recorded to estimate the size of territories and core area of occupancy. To quantify habitat preferences, vegetation composition and structure were measured in areas where Bristlebirds were present, as well as surrounding areas where they were not detected. The population in the survey areas was estimated at between 70 and 86 individuals in the 170-ha survey area. The estimated size of territories of eight selected pairs of Bristlebirds ranged from 0.5 to 3 ha, with core areas of occupancy ranging from 0.2 to 0.6 ha. During the nesting season (August–November) Bristlebirds were detected at greater frequencies in the core area of occupancy within each territory. Significant associations were found between the presence of Bristlebirds and floristic associations dominated by the native environmental weeds Acacia sophorae and Leptospermum laevigatum. Bristlebird presence was significantly positively correlated with increasing vegetation density in the mid-canopy level (80–120 cm) indicating that vegetation structure is a key factor in habitat use.
Additional keywords: territory size, vegetation preferences, weed invasion.
Acknowledgements
The authors wish to thank Grainne Maguire, Susie Schickmann and Robert Mitchell for field assistance and data collation, and John Hill (Portland Aluminium) and David Cahill (Deakin University) for support and guidance. The following organisations are land managers of the Portland Heathland and provided assistance and support for the project: the Port of Portland, Portland Coast Water, Incitec Pivot, Point Danger Committee of Management, Department of Sustainability and Environment (Victoria) and Portland Aluminium. We are grateful for the statistical advice and assistance given by Dr John Aberton. Dr Rohan Clarke, Matt Dell and Angie Haslem provided invaluable comments on earlier drafts of this paper. This project was carried out under approval of Deakin University’s Animal Welfare Committee (project approval number A14/2001). Research funding was provided by the Australian Research Council, Alcoa World Alumina, the Department of Natural Resources & Environment (Victoria), the Holsworth Wildlife Research Fund and the School of Ecology & Environment of Deakin University. Three anonymous referees provided useful criticisms on earlier versions of the paper.
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