Emu Emu Society
Journal of BirdLife Australia

Trophic relationships between neighbouring White-bellied Sea-Eagles (Haliaeetus leucogaster) and Wedge-tailed Eagles (Aquila audax) breeding on rivers and dams near Canberra

Jerry Olsen A C , Esteban Fuentes A and A. B. Rose B

A Applied Ecology Research Group, University of Canberra, ACT 2601, Australia.

B Australian Museum, 6 College Street, Sydney, NSW 2010, Australia. Present address: 61 Boundary Street, Forster, NSW 2428, Australia.

C Corresponding author. Email: Jerry.Olsen@canberra.edu.au

Emu 106(3) 193-201 http://dx.doi.org/10.1071/MU05046
Submitted: 7 September 2005  Accepted: 12 May 2006   Published: 18 August 2006


The diet of the White-bellied Sea-Eagle (Haliaeetus leucogaster) in Australia is poorly known, especially inland. The diet of the Wedge-tailed Eagle (Aquila audax) is better known, but the overlap in prey used by the two eagles has not been studied. In four inland territories of White-bellied Sea-Eagles, and five territories of Wedge-tailed Eagles nesting close to them (range 1.6–5.1 km apart) between July 2002 and December 2004, we identified 116 and 118 prey items from nests of White-bellied Sea-Eagles and Wedge-tailed Eagles respectively. There was little overlap between the diets, and that of Wedge-tailed Eagles was similar to that reported elsewhere. In addition to fish, White-bellied Sea-Eagles specialised in aquatic birds, such as cormorants, grebes or ducks, and aquatic reptiles, such as turtles or water dragons, but tended to avoid terrestrial birds and reptiles, such as ravens and skinks, or mammals such as European Rabbits (Oryctolagus cuniculus) and macropods that were the main prey of nearby Wedge-tailed Eagles. Though food niche breadth was almost identical for the two eagles, Wedge-tailed Eagles captured significantly larger prey, as indicated by the geometric mean prey weight. Our results indicate that closely located breeding pairs of riparian Wedge-tailed Eagles and White-bellied Sea-Eagles were not competing for food, owing to the differences in foraging preferences, at least during the breeding season. We found no evidence to support the claim that the spread of rabbits assisted the increase of breeding numbers of White-bellied Sea-Eagles.


Aumann T. 2001 An intraspecific and interspecific comparison of raptor diets in the south-west of the Northern Territory Australian Wildlife Research 28 379 393 DOI

Baker-Gabb D. J. 1984 The breeding ecology of twelve species of diurnal raptor in north-western Victoria. Australian Wildlife Research 11 145 160 DOI

Begon M., Harper J. H., and Townsend C. R. (1990). ‘Ecology: Individuals, Populations and Communities.’ 2nd Edn. (Blackwell Scientific Publications: Oxford, UK.)

Brooker M. G. Ridpath M. G. 1980 The diet of the Wedge-tailed Eagle, Aquila audax, in Western Australia. Australian Wildlife Research 7 433 452 DOI

Brunner H., and Coman B. (1974). ‘The Identification of Mammalian Hair.’ (Inkata Press: Melbourne.)

Burton A. M. Olsen P. 1997 Niche partitioning by two sympatric goshawks in the Australian wet tropics: breeding-season diet. Wildlife Research 24 45 52 DOI

Collopy M. W. 1983 A comparison of direct observations and collections of prey remains in determining the diet of golden eagles. Journal of Wildlife Management 47 360 368

Debus S. (1998). ‘The Birds of Prey of Australia: A Field Guide.’ (Oxford University Press: Melbourne.)

Debus S. J. S. Rose A. B. 1999 Notes on the diet of the Wedge-tailed Eagle Aquila audax. Australian Bird Watcher 18 38 41

Dennis T. E. Lashmar A. F. C. 1996 Distribution and abundance of White-bellied Sea-Eagles in South Australia. Corella 20 93 102.

Eckert J. 1971 Birds of the Franklin Islands and Eyre Island, South Australia. Emu 71 61 64

Ferguson-Lees J., and Christie D. A. (2001). ‘Raptors of the World.’ (Christopher Helm: London.)

Fuentes E., Olsen J., and Rose A. B. (2003). The Wedge-tailed Eagle in the Canberra Region: 40 years after Leopold and Wolfe. In ‘Abstracts of the Australasian Ornithological Conference’, Australian National University, 10–13 December.[Abstract]

Fuentes E. Olsen J. Rose A. B. 2005 Breeding diet at two Whistling Kite nests near Canberra. Australian Field Ornithology 22 122 125

Garcia J. T. Arroyo B. E. 2005 Food-niche differentiation in sympatric Hen Circus cyaneus and Montagu’s Harriers Circus pygargus. Ibis 147 144 154

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

Hollands D. (1984). ‘Eagles, Hawks and Falcons of Australia.’ (Thomas Nelson: Melbourne.)

Hull C. 1986 The diet of the Wedge-tailed Eagle, Aquila audax, breeding near Melbourne. Corella 10 21 24

Jaksić F. M. 1983 The trophic structure of sympatric assemblages of diurnal and nocturnal birds of prey. American Midland Naturalist 109 152 162

Jaksić F. M. (2000). ‘Ecología de Comunidades.’ (Ediciones Universidad Católica de Chile: Santiago.)

Jaksić F. M. Delibes M. 1987 A comparative analysis of food-niche relationships and trophic guild structure in two assemblages of vertebrate predators differing in species richness: causes, correlations, and consequences. Oecologia 71 461 471 DOI

Johnsgard P. (1990). ‘Hawks, Eagles and Falcons of North America.’ (Smithsonian Institution Press: Washington.)

Korpimaki E. 1987 Dietary shifts, niche relationships, and reproductive output of coexisting Kestrels and Long-eared Owls. Oecologia 74 277 285 DOI

Layton J. 1996 White-bellied Sea-Eagles nesting near Canberra. Australasian Raptor Association News 17 17 19

Leopold A. S. Wolfe T. O. 1970 Food habits of nesting Wedge-tailed Eagles, Aquila audax, in south-eastern Australia. CSIRO Wildlife Research 15 1 17

Marchant S., and Higgins P. J. (Eds) (1990). ‘Handbook of Australian, New Zealand and Antarctic Birds. Vol. 1: Ratites to Ducks.’ (Oxford University Press: Melbourne.)

Marchant S., and Higgins P. J. (Eds) (1993). ‘Handbook of Australian, New Zealand and Antarctic Birds. Vol. 2: Raptors to Lapwings.’ (Oxford University Press: Melbourne.)

Marti C. D. (1987). Raptor food habits studies. In ‘Raptor Management Techniques Manual’. (Eds B. A. Giron Pendleton, B. A. Millsap, K. W. Cline and D. M. Bird.) pp. 67–80. (National Wildlife Federation: Baltimore, MD.)

Marti C. D., Korpimäki E., and Jaksić F. M. (1993). Trophic structure of raptor communities: a three-continent comparison and synthesis. In ‘Current Ornithology. Vol. 10’. (Ed. D. M. Power.) pp. 47–137. (Plenum Press: New York.)

May R. M. (1973). ‘Stability and Complexity in Model Ecosystems.’ (Princeton University Press: Princeton, NJ.)

McDonald P. G. Olsen P. D. Baker-Gabb D. J. 2003 Territory fidelity, reproductive success and prey choice in the Brown Falcon, Falco berigora: a flexible bet-hedger? Australian Journal of Zoology 51 399 414

Nilsson I. N. 1984 Prey weight, food overlap, and reproductive output of potentially competing Long-eared and Tawny Owls. Ornis Scandinavica 15 176 182

Olsen J. 1997 Notes on Sanford’s Sea-Eagle Haliaeetus sanfordi and other raptors in the Solomon Islands. Australian Bird Watcher 17 81 86

Olsen J., and Fuentes E. (2004). Preliminary report on the effect of the development of the Molonglo Valley on the community of birds of prey. Report to Australian Capital Territory Planning and Land Authority, Canberra.

Olsen J. Tucker A. D. 2003 A brood-size manipulation experiment with Peregrine Falcons, Falco peregrinus, near Canberra. Emu 103 127 132

Olsen J. Debus S. Rose A. B. Hayes G. 2004 Breeding success, cliff characteristics and diet of Peregrine Falcons at high altitude in the Australian Capital Territory. Corella 28 33 37

Pianka E. R. 1973 The structure of lizard communities. Annual Review of Ecology and Systematics 4 53 74

Schoener T. W. 1974 Resource partitioning in ecological communities. Science 185 27 39

Seguin J. F. Bayle P. Thibault J. C. Torre J. Vigne J. D. 1998 A comparison of methods to evaluate the diet of the Golden Eagle in Corsica. Journal of Raptor Research 32 314 318

Sharp A. Gibson L. Norton M. Ryan B. Marks A. Semeraro L. 2002 The breeding season diet of the wedge-tailed eagle (Aquila audax) in western New South Wales and the influence of Rabbit Calicivirus Disease. Wildlife Research 29 175 184

Shephard J. M. Catterall C. P. Hughes J. M. 2005 Long-term variation in the distribution of the White-bellied Sea-Eagle (Haliaeetus leucogaster) across Australia. Austral Ecology 30 131 145 DOI

Sherrod S. K. White C. M. Williamson F. S. L. 1977 Biology of the Bald Eagle on Amchitka Island, Alaska. Living Bird 15 143 182

Simmons R. E. Avery D. M. Avery G. 1991 Biases in diets determined from pellets and remains: correction factor for a mammal and bird eating raptor. Journal of Raptor Research 25 63 67

Smith G. C. 1985 An analysis of prey remains from Osprey Pandion haliatus and White-bellied Sea-Eagle Haliaeetus leucogaster feeding roosts. Emu 85 198 200

Steenhof K. 1983 Prey weights for computing percent biomass in raptor diets. Raptor Research 17 15 27

Steenhof K. Kochert M. N. 1985 Dietary shifts of sympatric buteos during a prey decline. Oecologia 66 6 16

Steenhof K. Kochert M. N. 1988 Dietary responses of three raptor species to changing prey densities in a natural environment. Journal of Animal Ecology 57 37 48

Strahan R. (Ed.) (2004). ‘The Mammals of Australia.’ (The Australian Museum and Reed – New Holland Books: Sydney.)

Wiersma J. 1996 Competition between Wedge-tailed Eagles and White-bellied Sea-Eagles for nests. Australasian Raptor Association News 17 23

Wink M. Heidrich P. Fentzloff C. A. 1996 mtDNA phylogeny of sea eagles (genus Haliaeetus) based on nucleotide sequences of the cytochrome b gene. Biochemical Systematics and Ecology 24 783 791

Export Citation