Breeding activity, nest site selection and nest spacing of wedge-tailed eagles, Aquila audax, in western New South Wales

Abstract

Eighty active and 59 inactive Wedge-tailed Eagle (Aquila audax) nests were located by opportunistic helicopter surveys, during the 1995–99 breeding seasons. The mean distance to nearest neighbour was used to estimate nesting densities, which were in the order of 1 pair per 3–9 km². This was considerably higher than that noted in other semi-arid zone studies (~1 pair per 40–48 km²) and reflected the concentration of nests along two mountain range systems. The lack of suitable nest sites across much of the study area was the probable cause of the clumped distribution of nests. In all, 85 active and inactive nests were visited on the ground during 1995–97 and data collected on nest site characteristics and habitat. Leopardwood (Flindersia maculosa), Beefwood (Grevillea striata) and White Callitris Pine (Callitris glaucophylla) were the most common tree species selected for nest sites; all three of these were commonly associated with the range habitat. Both Leopardwood and Beefwood characteristically display strong forks at approximately two-thirds the height of the tree and all three species are among the tallest tree species within the study area. These results support the general contention that Wedge-tailed Eagles display no preference for particular tree species and build their nests in the commonest tall trees available.