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Wedge-tailed Eagle

(Aquila audax)
Aboriginal names: "bilyana", "mullian", "nompie", "woorawa", "wulde", "maliyan" [gamilaraay, yuwaalaraay]
Size: 90 cm - 1.1 m; wing span 1.8-2.5 m

Habitat
(for details refer to a field guide)

Wedge-tailed Eagles (race "audax") inhabit most of the Australian continent. The only exception is basically the most arid part of Australia, i.e. the eastern half of WA, south of the Kimberleys and north of an about 100-200 km wide strip along the south coast. They are uncommon in the central part of the NT, south of the Gulf of Carpentaria and on Cape York. Race "fleayi" is found in Tasmania.

Wedge-tailed Eagles hunt in most inland habitats of Australia, except dense forest (such as rainforest). As carrion scavengers they are particularly well-adapted to semi-arid and arid environments.

Sightings

Wedge-tailed Eagles are quite common in the Narrabri region, in north-western NSW. We have seen them, mostly in pairs, quite regularly, either perched in treetops or sitting on their prey on the ground. Often seen soaring at great heights. Seen both in the plains and on the slopes of the Great Dividing Range.

Seen in various locations on a trip to outback NSW and South Australia in March 2008. Again, found both in hill country and riverina flood plains.

Photos

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Wedge-tailed Eagle on a perch

Wedge-tailed Eagle after it got annoyed with the photographer

Soaring Wedge-tailed Eagle

Wedge-tailed Eagle in flight (click on image to see what it had to put up with) - the little speck is a Willie Wagtail; note that these photos were taken with 15x magnification (f=500 mm)!)

Here a comparison of the wing shape when gliding (left) and soaring (right)

Here one seen from above

There are many who don't want "Wedgies" around - first an Australian Magpie...

...then an Australian Raven

Near-frontal view of an immature Wedge-tailed Eagle

Lateral view of an immature Wedge-tailed Eagle

Close-up view of an immature Wedge-tailed Eagle with its inner eyelids closed

The same bird as above, now with its eyes open

Two immature Wedge-tailed Eagle in a dead tree at the back of our property

Immature Wedge-tailed Eagle in flight; it left behind its catch of the day

Here the same bird as above, in a different phase of its wing beat

Immature Wedge-tailed Eagle, probably the same bird as above, soaring

"High-flyers"

Below a rough estimate of the altitude at which a Wedge-tailed Eagle was observed: Assuming that the airplane was flying at 10000 m altitude (33000 ft), based on its length of 70.6 m and the eagle's length of ca. 1 m, one can estimate from the relative apparent sizes that the eagle was seen at an altitude of roughly 800 m. The uncertainty in the length of the bird and the altitude of the airplane is about ±10%, making the total uncertainty of the bird's altitude about ±20%.

These two photos give an estimate of how high a "Wedgy" can fly; Wedge-tailed Eagle at 15x magnification (left) and, on the same scale, a Boeing 747-400 at cruising altitude (right)

Breeding information

Breeding season: Jun - Aug Eggs: 1 - 3 Incubation period: 45 days Fledging age: ca. 70 days

The breeding season dependss significantly on geographical latitude. In the tropical north Wedge-tailed Eagles breed Jan - Feb. Although there can be up to 3 eggs, normally only one, sometimes two chicks survive.

Nest

Type: Basket Material: Sticks, lined with fresh leaves Height above ground: 5 - 20 m

The nest will start relatively small and grow in size with time, up to a total weight of about one tonne. Therefore, Wedge-tailed Eagles choose the strongest forks available in the tallest suitable tree they can find.

Wedge-tailed Eagle's nest in the only tree worth its name in an arid part of the Flinders Ranges

Closer view of a different Wedge-tailed Eagle's nest in the same part of the Flinders Ranges, about 10 km from the one shown above

Eggs

Size: 75 x 58 mm Colour: Light-brown, heavily speckled with darker brown speckles Shape: Tapered oval

Behaviour

Social behaviour: Territorial Mobility: Sedentary Elementary unit: Pair

Australia does not have any vultures. The Wedge-tailed Eagle fills that void in the habitat. Together with ants and Whistling Kites they dispose of dead bodies.

Food

All raptors are carnivores. Wedge-tailed Eagles prey on animals as large as (young) kangaroos. They also scavenge on carrion, e.g. roadkill. The photo below indicates that immature birds start with smaller prey. They have been seen by us competing with adult Whistling Kites.

Here an immature Wedge-tailed Eagle's victim