The diet of powerful owls (Ninox strenua) and prey availability in a continuum of habitats from disturbed urban fringe to protected forest environments in south-eastern Australia
R. Cooke A D , R. Wallis B , F. Hogan A , J. White A and A. Webster CA School of Life and Environmental Sciences, Deakin University, Burwood Campus, 221 Burwood Highway, Burwood, Vic. 3125, Australia.
B Office of the Pro-Vice-Chancellor (Rural and Regional), Deakin University, Warrnambool Campus, Warrnambool, Vic. 3280, Australia.
C Department of Sustainability and Environment, Box Hill, Vic. 3128, Australia.
D Corresponding author. Email: raylene.cooke@deakin.edu.au
Wildlife Research 33(3) 199-206 https://doi.org/10.1071/WR05058
Submitted: 30 June 2005 Accepted: 16 March 2006 Published: 31 May 2006
Abstract
This study investigates the diet of six breeding pairs of powerful owls in the Yarra Valley Corridor in Victoria, Australia, and compares prey consumption with prey availability. The six sites represent a continuum of habitats, ranging from urban Melbourne, through the urban fringe interface to a more forested landscape. We found that powerful owls in the Yarra Valley Corridor are reliant almost exclusively on arboreal marsupial prey as their preferred diet, with 99% of their overall diet comprising four arboreal marsupial species. These four species (the common ringtail possum, common brushtail possum, sugar glider and greater glider) were also the most abundant species observed while spotlighting; however, their abundance varied along the continuum. There was a strong positive relationship with the presence of these species in the diet and their site-specific availability, indicating that the powerful owl is a generalist hunter, preying on the most available prey at a given site and in a given season. This study suggests that food resources are high in these disturbed urban fringe sites and it is unlikely that food availability in urban environments will limit the potential survival of urban powerful owls.
Acknowledgments
We thank the Holsworth Wildlife Research Fund, the M.A. Ingram Trust, Birds Australia, and Deakin University for providing financial support as without such support this research would not have been possible. We also acknowledge the constructive suggestions provided by referees of this manuscript.
Chafer, C. J. (1992). Observations of the powerful owl (Ninox strenua) in the Illawarra and Shoalhaven regions of New South Wales. Australian Bird Watcher 14, 77–84.
Cooke, R. , Wallis, R. , Webster, A. , and Wilson, J. (1997). Diet of a family of powerful owls (Ninox strenua) from Warrandyte, Victoria. Proceedings of the Royal Society of Victoria 109, 1–6.
Cooke, R. , Wallis, R. , and White, J. (2002b). Use of vegetative structure by powerful owls in outer urban Melbourne, Victoria, Australia – implications for management. Journal of Raptor Research 36, 294–299.
James, J. W. (1980). Food of the powerful owl (Ninox strenua) in south-eastern Queensland. Emu 80, 34–35.
Lavazanian, E. , Wallis, R. , and Webster, A. (1994). Diet of powerful owls (Ninox strenua) living near Melbourne, Victoria. Wildlife Research 21, 643–646.
| Crossref | GoogleScholarGoogle Scholar |
Pavey, C. R. (1992). Impact of powerful owl (Ninox strenua) predation on a population of the greater glider (Petauroides volans): a response to Kavanagh (1988). Australian Journal of Ecology 17, 463–467.
Pavey, C. R. (1994). Records of the food of the powerful owl (Ninox strenua) from Queensland. Sunbird 24, 30–39.
Tilley, S. (1982). The diet of the powerful owl (Ninox strenua) in Victoria. Australian Wildlife Research 9, 157–175.
| Crossref | GoogleScholarGoogle Scholar |
Van Dyck, S. , and Gibbons, D. (1980). Tuan (Phascogale tapoatafa) predation by powerful owls. Victorian Naturalist 97, 58–63.
Webster, A. , Cooke, R. , Jameson, G. , and Wallis, R. (1999b). Diet, roosts and breeding of powerful owls (Ninox strenua) in a disturbed, urban environment: a case for cannibalism? Or a case for infanticide? Emu 99, 80–83.
| Crossref | GoogleScholarGoogle Scholar |