Diet, occupancy and breeding performance of wedge-tailed eagle Aquila audax near Canberra, Australia 2002-2003: four decades after Leopold and Wolfe

W€ compared the diet and breeding performance of Wedge-tailed Eagles Aquila audax near Canberra in 2002-2003
wiih that tound in the same area in 1964 by Leopoid and Wolfe (1970). We located a total of 44 active territories, and
checked 26 of the 32 territories originally lound by Leopold and Wolfe. Twenty-two (85%) of the 26 were still occupied
after nearly four decades. Contrary to what was found in the 1964 survey, nine active nests were located inside the city
limits, with an average distance to paved roads of 720 + '132 metres (range 130-1 270 m) and to suburbs of 1 117 * 251
metres (range 26G-2 000 m). Four nests were less than 500 metres from houses, but only one territory was completely
surrounded by urban areas.
Fledgling rates were greater in 2002-03 than in 1964 (l .1 versus 0.8 young per tenitory) mainly because more pajrs
fledged two young in the 2002-2003 survey, and there was a decrease in the number of pairs lhat fledged no young.
ln 2002-2003,492 prey items were recorded lrom 33 territories. Fifty-seven different species were found: '19
mammals, 20 birds, seven reptiles and one crustacean. Mammals and birds were the dominant groups by number, 54.7
and 41.9 percent respectively, and mammals dominated by biomass (95.3%). The breeding dist in 2002-2003 was
dominated by macropods, representing 19.9 percent (n = 98) of the total items and 45.6 percont of biomass. The most
important species among these macropods was the EasternG rey Kangaroo( 13.6 and 31.20,6b y number and biomass
respectively)O. ther importanti temsw ere the EuropeanR abbit (16.9a nd 9.5% by numbera nd biomass)anda dult sheep
(3.3 and 19.7%).A mong birds, the parrots and cockatoos, Order Psittaciformes,r epresented1 2.8 percent of the total
items, but their contribution to the biomass was negligible (1.1%). Ihe Galah (5.1%, n = 25) and Australian Magpie
(6.1%, n = 30) w€re the most important bird prey species.
The propodional contribution of the different prey categories was signiticantly different between the two time
periods. Three groups decreased significantly: European Rabbit (43.8% in 1964 v 16.9% in 2002-2003), Hare (15.8 v
7.9%) and lamb (8.9 v 1.8%); and three others showed significant increases:m acropods (1.9 v 19.4o/o:)p,a rrots (3.5 v
10.9%) and Other Birds (4.6 v 17o^r.
As long as the current high levels of diverse prey are avaihble for the eagles near Canberra, it is likely that the
population will remain stable, and young fledged per territory will remain high.