Food habits of nesting Wedge-Tailed Eagles, Aquila audax, in South-Eastern Australia

Abstract

Food habits of nesting wedge-tailed eagles were studied by gathering and identifying materials brought to the nests to feed the young. Near Canberra, A.C.T., 31 inactive nests yielded 1923 identifiable food fragments and 157 pellets. In north-western New South Wales 28 nests yielded 1274 identified fragments and 52 pellets. During the nesting season 18 active nests were visited at least weekly and 260 fresh prey animals were recorded. Rabbits constituted the primary prey of eagles. Near Canberra the hare was the next most important species, followed by birds, sheep and lambs, small mammals, and lizards. In the arid interior, kangaroos and lizards were of considerable importance, taking the place of the hare, which does not occur there. Lamb remains constituted about 7% of the eagles' diet. An unknown portion of this is presumed to be carrion. In the Canberra area the density of the population of resident adult eagles was established to be about one pair per 12 square miles. Sheep flocks within an average nesting territory produced about 4000 lambs, of which the pair of eagles might take at most a few individuals. Although the impact of predation by nesting eagles on the pastoral industry in the area could not have been significant, non-territorial wandering young eagles might have caused trouble in the lambing paddocks, but no data were obtained on these birds. As a result of clearing of forests and the introduction of rabbits and other exotic mammals, south-eastern Australia is probably a better habitat for wedge-tailed eagles than it was originally.