An eagle in flight displays its trademark wedge-shaped tail. Credit:Nathan Piesse Australia's largest raptor, and one of the world's biggest birds of prey, was mercilessly hunted down as a lamb killer, complete with a bounty on its head, and in the 50 years until 1974 at least a million eagles were killed in Australia under this system. In fact until 1989, wedge-tailed eagles were still considered vermin in WA, despite many studies, including a detailed 10-year study published as far back as 1969, which showed eagles accounted for less than one per cent of lamb deaths and that most eagle "kills" were simply the big birds feeding on the 20 per cent of lambs that died through illness or mismothering. Ironically, the same studies showed that between 30 and 92 per cent of the eagles' diet was made up of rabbits - one of Australian farmers' greatest enemies. By killing off their eagles landowners were destroying their best ally against the rabbit plagues that lay waste to crops and grazing country alike. The studies also showed that eagles took a heavy toll on those other two introduced feral plagues - the fox and the feral cat.

A wedge-tail scans for food from a tree. Credit:Spencer Ford Thankfully the wedge-tail is now listed as "protected" in WA, although individuals and companies can apply for special licenses to kill them if they are causing "economic damage". An adaptable hunter, the wedge-tail lives in a wide range of environments across mainland Australia and Tasmania, as well as southern New Guinea, and, as its name suggests, is easily identifiable in flight by its wedge-shaped tail. Arguably the world's fourth largest eagle, the female is bigger than the male with the wingspan of one female measured at a massive 2.84 metres. These wings enable wedge-tails to soar on thermals up to altitudes of 1800 metres or more. In the build-up to mating the breeding pair perform aerobatics together over their territory before either building a nest of sticks or adding sticks to an old nest in the fork of a tree. These huge nests can be up to five metres wide and five metres deep.

Here the female usually lays two eggs and both sexes take part in incubating the eggs and rearing the chicks, although, like carnaby's cockatoo, more often than not only one chick makes it through to the fledgling stage. Observing these huge birds is fascinating, and now anyone can get an intimate look at their lives thanks to WA wedge-tail expert Simon Cherriman's Wedge-tailed Eagle Tracking website, where three WA eagles are being tracked by satellite. DID YOU KNOW? Although an eagle weighs only a fraction of the weight of a human being, its eyes are roughly the same size and weight as ours and their eyesight is estimated to be four to eight times stronger. An eagle is said to be able to spot a rabbit more than three kilometres away, which is roughly equivalent to a person on top of an eight storey building being able to see an ant crawling on the pavement at ground level.

The photographs with this article were generously provided by members of the Western Australian Birds Facebook site. MORE BIRDS OF PERTH STORIES BIRDS OF PERTH PHOTO GALLERY Follow WAtoday on Twitter @WAtoday