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

Diets of Wedge-tailed Eagles (Aquila audax) and Little Eagles (Hieraaetus morphnoides) Breeding Near Canberra, Australia

“…The LE may be declining in parts of southeastern Australia, and WTEs may be implicated in this decline (Australian Capital Territory; Osgood 2006). Olsen et al (2008Olsen et al ( , 2009 showed a loss by 2007 of 10 of 11 original pairs that were present in 1992 in the Australian Capital Territory. The LE is now classified as vulnerable in the Australian Capital Territory (Olsen et al 2009).…”

“…Olsen et al (2008Olsen et al ( , 2009 showed a loss by 2007 of 10 of 11 original pairs that were present in 1992 in the Australian Capital Territory. The LE is now classified as vulnerable in the Australian Capital Territory (Olsen et al 2009). Barrett et al (2007) reported a decrease of 38.7% for LEs in New South Wales, based on data from the first Atlas of Australian Birds (conducted between 1977 and 1981), and the New Atlas of Australian Birds (conducted between 1998 and2001;Barrett et al 2003).…”

“…Given the published literature indicating that both eagles consume rabbits, we concluded that there was potential for interspecific competition. Studies of dietary relationships between raptor species are often performed at a regional as opposed to a local scale, and it is assumed that niche overlap indicates potential competition (Jaksić 1983, Jaksić and Delibes 1987, Marti et al 1993, Burton and Olsen 1997, Garcia and Arroyo 2005, Olsen et al 2006a. However, to clearly understand the effect of competition, studies should occur at a local scale, between neighboring pairs (Steenhof and Kochert 1985, 1988, Marti et al 1993.…”

“…In southern temperate Australia, LEs prey mainly on small mammals (especially juvenile and immature European rabbits [Oryctolagus cuniculus]), and some birds (mainly parrots and passerines ,500 g), lizards and invertebrates, and rarely carrion, although in some parts of the New South Wales tablelands, they consume many small birds ,100 g (Debus 1984, Bollen 1989, 1991, Olsen et al 2006b, Debus et al 2007a, Debus and Ley 2009. In southern semiarid and arid areas their diet is similar to that in the temperate zone (Baker-Gabb 1984, Falkenberg et al 2000, but in more northerly (subtropical) arid areas, they take more lizards and invertebrates and far fewer rabbits.…”

“…However, WTEs may displace LEs by nesting close to them (Olsen 1995, Olsen et al 2006b). Given the published literature indicating that both eagles consume rabbits, we concluded that there was potential for interspecific competition.…”