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Australian Journal of Zoology Australian Journal of Zoology Society
Evolutionary, molecular and comparative zoology
RESEARCH ARTICLE

Reversed sexual dimorphism and altered prey base: the effect on sooty owl (Tyto tenebricosa tenebricosa) diet

Rohan J. Bilney A , John G. White A and Raylene Cooke A B
+ Author Affiliations
- Author Affiliations

A School of Life and Environmental Sciences, Deakin University, 221 Burwood Highway, Burwood, Vic. 3125, Australia.

B Corresponding author. Email: raylene.cooke@deakin.edu.au

Australian Journal of Zoology 59(5) 302-311 https://doi.org/10.1071/ZO11101
Submitted: 15 December 2011  Accepted: 13 April 2012   Published: 11 May 2012

Abstract

The ecology and function of many Australian predators has likely been disrupted following major changes in prey base due to declines in distribution and abundance of small mammals following European settlement. This study investigated various aspects of the dietary ecology of sooty owls (Tyto tenebricosa tenebricosa), including sexual variation as they potentially exhibit the greatest degree of reversed sexual dimorphism of any owl species worldwide. Sooty owls are highly opportunistic predators of non-volant small mammals, consuming most species known to exist in the region, so their diet fluctuates seasonally and spatially due to varying prey availability, and is particularly influenced by the breeding cycles of prey. Significant intersexual dietary differences existed with female sooty owls predominantly consuming much larger prey items than males, with dietary overlap at 0.62. The current reliance on relatively few native mammalian species is of conservation concern, especially when mammal declines are unlikely to have ceased as many threatening processes still persist in the landscape. Sooty owl conservation appears inextricably linked with small mammal conservation. Conservation efforts should be focussed towards improving prey densities and prey habitat, primarily by implementing control programs for feral predators and preventing the loss of hollow-bearing trees throughout the landscape.

Additional keywords: Australia, biomass, hollow dependant, predator, seasonal.


References

Amadon, D. (1975). Why are female birds of prey larger than males? The Journal of Raptor Research 9, 1–11.

Andersson, M., and Norberg, R. A. (1981). Evolution of reversed sexual size dimorphism and role partitioning among predatory birds, with a size scaling of flight performance. Biological Journal of the Linnean Society. Linnean Society of London 15, 105–130.
Evolution of reversed sexual size dimorphism and role partitioning among predatory birds, with a size scaling of flight performance.Crossref | GoogleScholarGoogle Scholar |

Bennett, A. F., Lumsden, L. F., Alexander, J. S. A., Duncan, P. E., Johnson, P. G., Robertson, P., and Silveira, C. E. (1991). Habitat use by arboreal mammals along an environmental gradient in north-eastern Victoria. Wildlife Research 18, 125–146.
Habitat use by arboreal mammals along an environmental gradient in north-eastern Victoria.Crossref | GoogleScholarGoogle Scholar |

Bilney, R. J., Cooke, R., and White, J. (2006). Change in the diet of sooty owls (Tyto tenebricosa) since European settlement: from terrestrial to arboreal prey and increased overlap with powerful owls. Wildlife Research 33, 17–24.
Change in the diet of sooty owls (Tyto tenebricosa) since European settlement: from terrestrial to arboreal prey and increased overlap with powerful owls.Crossref | GoogleScholarGoogle Scholar |

Bilney, R. J., Kavanagh, R. P., and Harris, J. M. (2007). Further observations on the diet of the sooty owl (Tyto tenebricosa) in the Royal National Park, Sydney. Australian Field Ornithology 24, 64–69.

Bilney, R. J., Cooke, R., and White, J. G. (2010). Underestimated and severe: small mammal decline from the forests of south-eastern Australia since European settlement, as revealed by a top order predator. Biological Conservation 143, 52–59.
Underestimated and severe: small mammal decline from the forests of south-eastern Australia since European settlement, as revealed by a top order predator.Crossref | GoogleScholarGoogle Scholar |

Bilney, R. J., Cooke, R., and White, J. G. (2011a). Potential competition between two top-order predators following a dramatic contraction in the diversity of their prey base. Animal Biology 61, 29–47.
Potential competition between two top-order predators following a dramatic contraction in the diversity of their prey base.Crossref | GoogleScholarGoogle Scholar |

Bilney, R. J., White, J. G., L’Hotellier, F. A., and Cooke, R. (2011b). Spatial ecology of sooty owls in south-eastern Australian coastal forests: implications for forest management and reserve design. Emu 111, 92–99.
Spatial ecology of sooty owls in south-eastern Australian coastal forests: implications for forest management and reserve design.Crossref | GoogleScholarGoogle Scholar |

Braithwaite, L. W., Binns, D. L., and Nowlan, R. D. (1988). The distribution of arboreal marsupials in relation to Eucalypt forest types in the Eden (N.S.W.) woodchip concession area. Australian Wildlife Research 15, 363–373.
The distribution of arboreal marsupials in relation to Eucalypt forest types in the Eden (N.S.W.) woodchip concession area.Crossref | GoogleScholarGoogle Scholar |

Burbidge, A. A., and McKenzie, N. L. (1989). Patterns in the modern decline of Western Australia’s vertebrate fauna: causes and conservation implications. Biological Conservation 50, 143–198.
Patterns in the modern decline of Western Australia’s vertebrate fauna: causes and conservation implications.Crossref | GoogleScholarGoogle Scholar |

Burbidge, A. A., McKenzie, N. L., Brennan, K. E. C., Woinarski, J. C. Z., Dickman, C. R., Baynes, A., Gordon, G., Menkhorst, P. W., and Robinson, A. C. (2008). Conservation status and biogeography of Australia’s terrestrial mammals. Australian Journal of Zoology 56, 411–422.
Conservation status and biogeography of Australia’s terrestrial mammals.Crossref | GoogleScholarGoogle Scholar |

Carey, A. B., Horton, S. P., and Biswell, B. L. (1992). Northern spotted owls: influence of prey base and landscape character. Ecological Monographs 62, 223–250.
Northern spotted owls: influence of prey base and landscape character.Crossref | GoogleScholarGoogle Scholar |

Catling, P. C. (1991). Ecological effects of prescribed burning practices on mammals of south eastern Australia. In ‘Conservation of Australia’s Forest Fauna’. (Ed. D. Lunney.) pp. 353–363. (Royal Zoological Society of New South Wales: Sydney.)

Catling, P. C., and Burt, R. J. (1995). Studies of the ground-dwelling mammals of eucalypt forests in south-eastern New South Wales: the effect of habitat variables on distribution and abundance. Wildlife Research 22, 271–288.
Studies of the ground-dwelling mammals of eucalypt forests in south-eastern New South Wales: the effect of habitat variables on distribution and abundance.Crossref | GoogleScholarGoogle Scholar |

Clarke, K. R., and Warwick, R. M. (1994). ‘Changes in Marine Communities: an Approach to Statistical Analysis and Interpretation.’ (Plymouth Marine Laboratory: Plymouth, UK.)

Clarke, M. F. (2008). Catering for the needs of fauna in fire management: science or just wishful thinking? Wildlife Research 35, 385–394.
Catering for the needs of fauna in fire management: science or just wishful thinking?Crossref | GoogleScholarGoogle Scholar |

DEC (2006). NSW Recovery Plan for the large forest owls: powerful owl (Ninox strenua), sooty owl (Tyto tenebricosa) and masked owl (Tyto novaehollandiae). Department of Environment and Conservation, Sydney.

Dexter, N., and Murray, A. J. (2009). The impact of fox control on the relative abundance of forest mammals in East Gippsland, Victoria. Wildlife Research 36, 252–261.
The impact of fox control on the relative abundance of forest mammals in East Gippsland, Victoria.Crossref | GoogleScholarGoogle Scholar |

Duffy, J. E. (2002). Biodiversity and ecosystem function: the consumer connection. Oikos 99, 201–219.
Biodiversity and ecosystem function: the consumer connection.Crossref | GoogleScholarGoogle Scholar |

Earhart, C. M., and Johnson, N. K. (1970). Size dimorphism and food habits of North American owls. The Condor 72, 251–264.
Size dimorphism and food habits of North American owls.Crossref | GoogleScholarGoogle Scholar |

Garnett, S. T., Loyn, R. H., and Lowe, K. (2003). Loss of hollow-bearing trees from Victorian native forests and woodlands. Action Statement No. 192. Department of Sustainability and Environment, Melbourne.

Gibbons, P., and Lindenmayer, D. (2002). ‘Tree Hollows and Wildlife Conservation in Australia.’ (CSIRO Publishing: Melbourne.)

Henke, S. E., and Bryant, F. C. (1999). Effects of coyote removal on the faunal community in western Texas. Journal of Wildlife Management 63, 1066–1081.
Effects of coyote removal on the faunal community in western Texas.Crossref | GoogleScholarGoogle Scholar |

Higgins, P. (1999). ‘Handbook of Australian, New Zealand and Antarctic birds. Volume 4: Parrots to Dollarbird.’ (Oxford University Press: Melbourne.)

Hollands, D. (2008). ‘Owls, Frogmouths and Nightjars of Australia.’ (Bloomings Books: Melbourne.)

Holmes, G. (1994). Prey of the sooty owl in subtropical Australia. Sunbird 24, 25–27.

Hunter, M. D., and Price, P. W. (1992). Playing chutes and ladders: heterogeneity and the relative roles of bottom-up and top-down forces in natural communities. Ecology 73, 724–732.

Kavanagh, R. P. (1997). Ecology and management of large forest owls in south-eastern Australia. Ph.D. Thesis, University of Sydney.

Kavanagh, R. P. (2000). Effects of variable-intensity logging and the influence of habitat variables on the distribution of the greater glider (Petauroides volans) in montane forest, southeastern New South Wales. Pacific Conservation Biology 6, 18–30.

Kavanagh, R. P. (2002a). Comparative diets of the powerful owl (Ninox strenua), sooty owl (Tyto tenebricosa) and masked owl (Tyto novaehollandiae) in southeastern Australia. In ‘Ecology and Conservation of Owls’. (Eds I. Newton, R. P. Kavanagh, J. Olsen and I. Taylor.) pp. 175–191. (CSIRO Publishing: Melbourne.)

Kavanagh, R. P. (2002b). Conservation and management of large forest owls in southeastern Australia. In ‘Ecology and Conservation of Owls.’ (Eds I. Newton, R. P. Kavanagh, J. Olsen, and I. Taylor.) pp. 201–219. (CSIRO Publishing: Melbourne.)

Kavanagh, R. P., and Bamkin, K. L. (1995). Distribution of nocturnal forest birds and mammals in relation to the logging mosaic in south-eastern New South Wales, Australia. Biological Conservation 71, 41–53.
Distribution of nocturnal forest birds and mammals in relation to the logging mosaic in south-eastern New South Wales, Australia.Crossref | GoogleScholarGoogle Scholar |

Kavanagh, R. P., and Webb, G. A. (1998). Effects of variable-intensity logging on mammals, reptiles and amphibians at Waratah Creek, southeastern New South Wales. Pacific Conservation Biology 4, 326–347.

Kavanagh, R. P., Debus, S., Tweedie, T., and Webster, T. (1995). Distribution of nocturnal forest birds and mammals in north-eastern New South Wales: relationships with environmental variables and management history. Wildlife Research 22, 359–377.
Distribution of nocturnal forest birds and mammals in north-eastern New South Wales: relationships with environmental variables and management history.Crossref | GoogleScholarGoogle Scholar |

Kinnear, J. E., Sumner, N. R., and Onus, M. L. (2002). The red fox in Australia: an exotic predator turned biocontrol agent. Biological Conservation 108, 335–359.
The red fox in Australia: an exotic predator turned biocontrol agent.Crossref | GoogleScholarGoogle Scholar |

Krüger, O. (2005). The evolution of reversed sexual size dimorphism in hawks, falcons and owls: a comparative study. Evolutionary Ecology 19, 467–486.
The evolution of reversed sexual size dimorphism in hawks, falcons and owls: a comparative study.Crossref | GoogleScholarGoogle Scholar |

Lazenby-Cohen, K. A., and Cockburn, A. (1993). Intense predation by owls on lekking brown antechinus Antechinus stuartii. In ‘Australian Raptor Studies’. (Ed. P. Olsen.) pp. 175–180. (RAOU: Melbourne.)

Levins, R. (1968). ‘Evolution in Changing Environments.’ (Princeton University Press: Princeton.)

Lindenmayer, D. B., Cunningham, R. B., Tanton, M. T., Smith, A. P., and Nix, H. A. (1990). The conservation of arboreal marsupials in the montane ash forests of the central highlands of Victoria, southeast Australia. 1. Factors influencing the occupancy of trees with hollows. Biological Conservation 54, 111–131.
The conservation of arboreal marsupials in the montane ash forests of the central highlands of Victoria, southeast Australia. 1. Factors influencing the occupancy of trees with hollows.Crossref | GoogleScholarGoogle Scholar |

Lindenmayer, D. B., Cunningham, R. B., and Donnelly, C. F. (1997). Decay and collapse of trees with hollows in eastern Australian forests: impacts on arboreal marsupials. Ecological Applications 7, 625–641.
Decay and collapse of trees with hollows in eastern Australian forests: impacts on arboreal marsupials.Crossref | GoogleScholarGoogle Scholar |

Loyn, R. H., Traill, B. J., and Triggs, B. E. (1986). Prey of the sooty owl in East Gippsland, Victoria, Australia before and after fire. The Victorian Naturalist 103, 147–149.

Lundberg, A. (1986). Adaptive advantages of reversed sexual size dimorphism in European owls. Ornis Scandinavica 17, 133–140.
Adaptive advantages of reversed sexual size dimorphism in European owls.Crossref | GoogleScholarGoogle Scholar |

Lundie-Jenkins, G. (1993). The diet of the sooty owl (Tyto tenebricosa) in the Blue Mountains, NSW. Emu 93, 124–127.
The diet of the sooty owl (Tyto tenebricosa) in the Blue Mountains, NSW.Crossref | GoogleScholarGoogle Scholar |

Lunney, D. (1989). Effects of logging, fire and drought on possums and gliders in the coastal forests near Bega, NSW. Australian Wildlife Research 16, 207–215.
Effects of logging, fire and drought on possums and gliders in the coastal forests near Bega, NSW.Crossref | GoogleScholarGoogle Scholar |

McLaren, B. E., and Peterson, R. O. (1994). Wolves, moose, and tree rings on Isle Royale. Science 266, 1555–1558.
Wolves, moose, and tree rings on Isle Royale.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK2MXisVGlsr8%3D&md5=17dc6b30e37c131e961fca8850326587CAS |

Menkhorst, P. W. (1995). ‘Mammals of Victoria: Distribution, Ecology and Conservation.’ (Oxford University Press: Melbourne.)

Menkhorst, P. W., and Knight, F. (2001). ‘A Field Guide to the Mammals of Australia.’ (Oxford University Press: Melbourne.)

Mooney, N. (1993). Diet of the masked owl in Tasmania: past and present. In ‘Australian Raptor Studies’. (Ed. P. Olsen.) pp. 160–174. (RAOU: Melbourne.)

Morris, D. A., Augee, M. L., Gillieson, D., and Head, J. (1997). Analysis of a late quaternary deposit and small mammal fauna from Nettle Cave, Jenolan, New South Wales. Proceedings of the Linnean Society of New South Wales 117, 135–161.

Mueller, H. C. (1986). The evolution of reversed sexual dimorphism in owls: an empirical analysis of possible selective factors. The Wilson Bulletin 98, 387–406.

Newton, I. (1979). ‘Population Ecology of Raptors.’ (Poyser: Berkhamsted.)

Newton, I. (2002). Population limitation in Holarctic owls. In ‘Ecology and Conservation of Owls’. (Eds I. Newton, R. P. Kavanagh, J. Olsen. and I. Taylor.) pp. 3–29. (CSIRO Publishing: Melbourne.)

Palkovacs, E. P., and Post, D. M. (2008). Eco-evolutionary interactions between predators and prey: can predator-induced changes to prey communities feed back to shape predator foraging traits? Evolutionary Ecology Research 10, 699–720.

Peake, P., Conole, L. E., Debus, S. J. S., McIntyre, A., and Bramwell, M. (1993). The masked owl in Victoria. Australian Bird Watcher 15, 124–136.

Peel, B. (1999). ‘Rainforests and Cool Temperate Mixed Forests of Victoria.’ (Department of Natural Resources and Environment: Melbourne.)

Pianka, E. R. (1973). The structure of lizard communities. Annual Review of Ecology and Systematics 4, 53–74.
The structure of lizard communities.Crossref | GoogleScholarGoogle Scholar |

Robinson, A. C. (1987). The ecology of the bush rat, Rattus fuscipes (Rodentia: Muridae) in Sherbrooke Forest, Victoria. Australian Mammalogy 11, 35–49.

SAC (2001). Final recommendation on a nomination for listing: high frequency fire resulting in disruption of life cycle processes in plants and animals and loss of vegetation structure and composition (Potentially Threatening Process) (Nomination No. 565). Scientific Advisory Committee, Flora and Fauna Guarantee. Department of Natural Resources and Environment, Melbourne.

SAC (2003). Final Recommendation on a nomination for listing: inappropriate fire regimes causing disruption to sustainable ecosystem processes and resultant loss of biodiversity (Potentially Threatening Process) (Nomination No. 664) Scientific Advisory Committee, Flora and Fauna Guarantee. Department of Sustainability and Environment, Melbourne.

Schmitz, O. J., Hamback, P. A., and Beckerman, A. P. (2000). Trophic cascades in terrestrial systems: a review of the effects of carnivore removals on plants. American Naturalist 155, 141–153.
Trophic cascades in terrestrial systems: a review of the effects of carnivore removals on plants.Crossref | GoogleScholarGoogle Scholar |

Scotts, D. J. (1991). Old-growth forests: their ecological characteristics and value to forest-dependant vertebrate fauna of south-east Australia. In ‘Conservation of Australia’s Forest Fauna’. (Ed. D. Lunney.) pp. 147–159. (Royal Zoological Society of New South Wales: Sydney.)

Selander, R. K. (1966). Sexual dimorphism and differential niche utilization in birds. The Condor 68, 113–151.
Sexual dimorphism and differential niche utilization in birds.Crossref | GoogleScholarGoogle Scholar |

Sergio, F., Marchesi, L., and Pedrini, P. (2004). Integrating individual habitat choices and regional distribution of a biodiversity indicator and top predator. Journal of Biogeography 31, 619–628.
Integrating individual habitat choices and regional distribution of a biodiversity indicator and top predator.Crossref | GoogleScholarGoogle Scholar |

Short, J., and Smith, A. (1994). Mammal decline and recovery in Australia. Journal of Mammalogy 75, 288–297.
Mammal decline and recovery in Australia.Crossref | GoogleScholarGoogle Scholar |

Sinclair, A. R. E., Pech, R. P., Dickman, C. R., Hik, D., Mahon, P., and Newsome, A. E. (1998). Predicting effects of predation on conservation of endangered prey. Conservation Biology 12, 564–575.
Predicting effects of predation on conservation of endangered prey.Crossref | GoogleScholarGoogle Scholar |

Smith, P. (1984). Prey items of the sooty owl and barn owl at Bega, New South Wales. Corella 8, 71–72.

Smith, A. P., and Lindenmayer, D. (1988). Tree hollow requirements of Leadbeater’s possum and other possums and gliders in timber production ash forests of the Victorian central highlands. Australian Wildlife Research 15, 347–362.
Tree hollow requirements of Leadbeater’s possum and other possums and gliders in timber production ash forests of the Victorian central highlands.Crossref | GoogleScholarGoogle Scholar |

Snyder, N. R., and Wiley, W. S. (1976). Sexual size dimorphism in hawks and owls of North America. Ornithological Monographs 20, 1–96.

Storer, R. W. (1966). Sexual dimorphism and food habits in three North American accipiters. The Auk 83, 423–436.

Suarez, A. V., and Case, T. J. (2002). Bottom-up effects on persistence of a specialist predator: ant invasions and horned lizards. Ecological Applications 12, 291–298.
Bottom-up effects on persistence of a specialist predator: ant invasions and horned lizards.Crossref | GoogleScholarGoogle Scholar |

Temple, S. A. (1987). Do predators always capture substandard individuals disproportionately from prey populations? Ecology 68, 669–674.
Do predators always capture substandard individuals disproportionately from prey populations?Crossref | GoogleScholarGoogle Scholar |

Terborgh, J., Lopez, L., Nunez, P., Rao, M., Shahabuddin, G., Orihuela, G., Riveros, M., Ascanio, R., Adler, G. H., Lambert, T. D., and Balbas, L. (2001). Ecological meltdown in predator-free forest fragments. Science 294, 1923–1926.
Ecological meltdown in predator-free forest fragments.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3MXovFWrtbc%3D&md5=50e72469f209b0f041afdee087bdbce8CAS |

Tyndale-Biscoe, C. H., and Smith, R. F. C. (1969). Studies on the marsupial glider, Schoinobates volans (Kerr). II. Population structure and regulatory mechanisms. Journal of Animal Ecology 38, 637–650.
Studies on the marsupial glider, Schoinobates volans (Kerr). II. Population structure and regulatory mechanisms.Crossref | GoogleScholarGoogle Scholar |

Ward, J. P., Gutierrez, R. J., and Noon, B. R. (1998). Habitat selection by northern spotted owls: the consequences of prey selection and distribution. The Condor 100, 79–92.
Habitat selection by northern spotted owls: the consequences of prey selection and distribution.Crossref | GoogleScholarGoogle Scholar |

Wheeler, P., and Greenwood, P. J. (1983). The evolution of reversed sexual dimorphism in birds of prey. Oikos 40, 145–149.
The evolution of reversed sexual dimorphism in birds of prey.Crossref | GoogleScholarGoogle Scholar |