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Context Some ecologists argue that nesting success and abundance of wedge-tailed eagles (Aquila audax) are strongly linked to the abundance of introduced wild rabbits (Oryctolagus cuniculus). Consequently, concerns were expressed about eagle population viability when the biological control agent rabbit haemorrhagic disease virus (RHDV) heavily reduced rabbit numbers. However, observations following the spread of rabbit haemorrhagic disease (RHD) in Australia and Spain (where Aquila adalberti is an equivalent of A. audax) question this assertion. Eagle numbers did not fall even though rabbits declined regionally by up to 90% in both countries. Aims To reconsider the assumption of a strong link between rabbit abundance and wedge-tailed eagle breeding and population maintenance. Dispelling misconceptions, if any, about the eagles’ dependence on rabbits would benefit the future management of both eagles and rabbits. Methods We reviewed the literature associated with claims that eagles were heavily dependent on rabbits and asked whether these views could be substantiated given the lack of changes in eagle abundance following the spread of RHD. Data on eagle egg-clutch size and nesting success were also reviewed. Conclusions There is little evidence that eagles depend heavily on rabbits as prey. Instead, as rabbits decline, more kangaroos, reptiles and birds are eaten, partly because more native prey becomes available. Eagles have a high proportion of rabbits in their diets mainly where degradation of natural ecosystems, including that caused by rabbits, results in native prey being rare or unavailable. There has been minimal variation in average clutch size following major perturbations in rabbit population size. Implications Rather than perpetuating the idea that high populations of rabbits are needed for wedge-tailed eagle conservation, resources would be better re-directed into understanding continental-scale eagle population dynamics. This would provide a more rational framework to assist decisions on future biological control agents for rabbits.

The diet of the Australian Hobby Falco longipennis was studied in Canberra (ACT), in the summers of 2002–2003 to 2004–2005 and 2005–2006 to 2008–2009 by analysis of prey remains and pellets (28 and 40 collections for a total of 229 and 132 prey items from six and four nests, respectively). The Hobbies’ breeding diet in the first period consisted of 73% birds, 1% microbats and 26% insects by number, and 98% birds, <1% microbats and 1% insects by biomass, mainly parrots (Psittaculidae), Common Starlings Sturnus vulgaris and sparrows Passer sp. In the second period, it consisted of 94% birds, 3% mammals (mostly microbats), 2% lizards and <1% insects by number, and was more dominated by Starlings and other introduced birds, with the change perhaps reflecting a recent decline in local insect abundance. The Hobby’s dietary metrics correspondingly shifted to a greater Geometric Mean Prey Weight and narrower food niche. The Hobby’s diet overlapped moderately (42%) with that of the similarly sized Collared Sparrowhawk Accipiter cirrocephalus in the ACT over the same timeframe, although the two are separated by foraging habitats and methods.