Wedge-tailed Eagles

The entirely apt scientific name of the wedge-tailed eagle is aquila audax: respectively, these Latin words mean eagle, and bold and daring. A grand official name befitting this magnificent bird. The spangled drongo (a less spectacular Australian native bird), can only wish for such a title. The wedge-tail is the largest raptor in Australia, and one of the largest eagles in the world.

They are found throughout mainland Australia and Tasmania. The adult female is larger than the adult male. The wingspan of an adult is typically around 2.3m (approx. 7’6″), they stand about 1m tall (approx. 3’3″) and can weigh up to 5kgs. There are reports of wingspans of 2.8m (approx. 9’2″). They have large powerful talons, and feathery ‘trousers’ covering their legs. Their colour vision is superior to that of humans. They also have very sophisticated binocular vision (also superior to that of humans) enabling them to pinpoint prey from great distances. They build very large nests.

They are monogamous, and very territorial, especially in breeding season. Their life expectancy is around 20 years, with recorded instances of some living much longer. They often hunt in pairs. Being such powerful fliers they can lift and fly with prey equalling their own weight (up to 5kgs): source: https://www.wildlife.vic.gov.au/__data/assets/pdf_file/0017/115343/Wedge-tailed-Eagle.pdf).

Wedge-tailed eagles get darker as they get older. They are strong fliers and highly skilled at soaring to significant altitudes (6,000 feet and sometimes higher) using thermals.

Airborne encounters with wedge-tailed eagles

#1

Hang gliding log book extract about flying with eagle.
This 1993 entry from my hang gliding log book records among other things (such as my glowing review of my landing, which suggests perhaps that not all my landings were of this quality…) my first flying encounter with a wedge-tailed eagle. Ben Nevis is a mountain in western Victoria, not far from Ararat. It has a large granite area from which a foot launch in a hang glider can safely be made. The mountain and the surrounding area generate a lot of thermal lift, which attracts hang glider pilots and wedge-tailed eagles.

The brief reference in my log to flying over a wedge-tailed eagle and maintaining height is a reference to me using the circling eagle directly ahead and not far below me to identify the location of a thermal. I maintained height for a short time in the thermal as the eagle continued to climb to my height (and then beyond). But for the three to four 360° turns I flew in an attempt to stay in the thermal, I was at the same height as the circling eagle. The words ‘great sight’ are quite inadequate to describe the experience of flying in close proximity to and sharing a thermal with an eagle soaring with wings at full stretch. That he continued to climb while I did the opposite and landed in the paddocks below is beside the point.

#2

Almost two years after sharing a thermal briefly with an eagle at Ben Nevis, I had another encounter with a wedge-tailed eagle while flying my hang glider (the Enterprise Wings Combat 152), this time in the Mallee in the north-west of Victoria in midsummer. It was a very hot day with a pre-frontal strong and gusty nor’westerly wind. We were staying in the area for a week of summer flying, tow-launching on a long rope towed by a car in the huge dusty paddocks near Birchip. Nobody launched until late in the afternoon when the wind and willy-willys had settled down. I launched around 4pm, released the tow rope at 900′ above the paddock, found a thermal and climbed out heading roughly south. I was heading towards Wycheproof and landed in a paddock 4km south of the town after a flight of a little over an hour. This was my personal best cross-country distance of 38km.

Staying airborne was a matter of locating a thermal (there were plenty of them), finding the centre of it where the lift was strongest, climbing in the core of the thermal until it either petered out or drifted downwind of the road I was following to Wycheproof, then finding another thermal and repeating. At one stage early in the flight I was down to 1700 feet above the paddocks before I found the next thermal, which turned out to be quite strong. I climbed in it until I was 6,550 feet above the small town of Dumosa.

While slowly descending through 6,000′ or so, a dark bird in the distance ahead of me and higher than me, dived and flew straight at me at speed. It was a large wedge-tailed eagle. As it neared me it extended its wings full span, pulled up squawking angrily with its legs and talons extended. I thought it was going to hit me or the glider. It all happened very fast. I have friends who have had eagles strike the sail or the the rigging wires of their hang glider in flight (eagle and pilot fortunately disengaged unscathed on each occasion). But the eagle banked away sharply and there was no contact. It disappeared as quickly as it came. I suppose it was an intimidatory display in defence of its territory. At 6,000 feet above the ground, the sky looked huge and the farming land below looked vast. I can only guess at the size of the territory this eagle was laying claim to rule.

The eagle achieved its aim. I haven’t returned to that part of the sky.

#3

Marriners lookout Apollo Bay 800 feet below my hang glider
This is a hang glider pilot’s view of Marriners Lookout at Apollo Bay. The walking track and foot launch site (from which I took off) is just above the parked hang glider. The triangular light-coloured hang glider on the ground would have a wingspan of 10m (33 feet) or so. As stated above, the typical wingspan of an adult wedge-tailed eagles is around 2.3m (7’6″). I was probably flying 1500 feet or so above sea level when this was taken, looking out over the ocean to the south east. That would put me around 800 feet above launch height. The shiny black thing is one of two neoprene mittens fitted permanently to the base bar of the A-frame of the hang glider. The grey object on the left is my altimeter and vertical speed indicator. (Aviation universally uses feet for measuring altitude).

While flying from Marriners lookout some years ago at about the altitude shown in the photo, a resident wedge-tailed eagle took up position behind my hang glider. I spotted him when I was checking over my shoulder as I commenced a gentle 180° turn while gaining height in good ridge lift. I did a few small turns and checked behind me again – the eagle was doing exactly the same turns as I was doing. I was being shadowed by an eagle.

Then the eagle overtook me and took up position not far in front of me and just a little lower than I was. Once again, when I turned so did the eagle. It was a sunny day, and I had an uninterrupted view of the upper surface of this large bird with its wings fully spread and its tip feathers fanned out like finger tips as eagles do in light air. Anyone who thinks an eagle is simply brown is wrong. If there is a single key colour it is more of a golden brown. But there is so much more. The feathers right across the top of its wings shone with the most beautiful array of black markings, flashes of white and many shades of brown and gold as it banked gently left and right in sync with me. The wings were moving in so many different ways, some obvious and some very fine as feathers and wing size and shape were constantly changed to maintain the perfect aerofoil to achieve the perfect aerodynamic performance.

The eagle’s head would turn very slightly from side to side, which I took to be his way of keeping me clearly in sight. We flew in formation for a pass or two left and right then the eagle peeled off and I lost sight of him.

It was a privilege to have this bird choose to fly near me and, for a short time, with me – even if its motive was to educate me as to exactly who controlled the territory into which I had flown. I have never forgotten the dazzling display of the colour and structure and movement of its wings viewed from directly above in bright sunlight.

The eagles have landed

A pair of wedge-tailed eagles recently developed an interest in a paddock not far from Apollo Bay, or to be exact, in a couple of dead lamb carcases in the paddock. The pair did a lot of flying over the paddock and over adjacent paddocks, occasionally landing in trees lining one side of the paddock, and occasionally landing on the grass amongst the stock. I saw them feeding on the carcase, but I also saw them just standing by as crows and other birds did the same thing. At no time did I see them showing any interest in livestock.

As the Barham River and its swampy banks separated me from the eagles in the paddock, these shots were all taken with the telephoto lens working hard.

Wedge-tailed eagle standing in grassy paddock.
The wedge-tailed eagle never fails to impress.
Pair of wedge-tailed eagles in grassy paddock.
The feather ‘trousers’ on the legs are clear in this and the next shot. The wedge tail is a cagey bird, always keeping an eye on the big picture. Here it seems they have divided lookout out duty to cover the full 360° around them.
Pair of wedge-tailed eagles in grassy paddock.
Wedge tailed eagle standing in paddock with sheep and cattle.
Peaceful coexistence.
Wedge-tailed eagle near crow eating sheep carcase.
The eagle allowed the crow to feed on the carcase without interruption.

Flying as a pair

Pair of wedge-tailed eagles flying together.
It can be a photographic challenge getting a photo of the underwing of an eagle (or of any bird in normal flight) in natural light. But when the bird on the right banked sharply with the sun behind me, all of the underside of one wing and half of the other were momentarily illuminated by the sun. The colours and markings under the wings are at their best in such light.
Pair of wedge-tailed eagles flying in close formation.
These two were gliding when this was taken. The dihedral of the wedge tail’s wings (the angle of inclination of the wings upward and away from the body) is a relatively shallow angle when gliding, as shown here.
The white-bellied sea eagle by comparison, when viewed head-on as it glides, has a greater dihedral angle ie the wings are noticeably more upswept. This is a reliable way to distinguish between the two species in the field, when they are seen (even at a distance) approaching the viewer head-on.
Wedge-tailed eagles landing in a gum tree.
2.3m or more of moving wings is a lot to deal with when landing in the thin upper branches of a gum tree. They did it, but the elegance and perfect economy and efficiency of movement they display in the air was absent in this landing manoeuvre.
Wedge-tailed eagles landing in a gum tree.
Crop of the previous photo.

Manoeuvring in the air

Adult wedge-tailed eagle in flight.
The size of the talons can be partly gauged in this photo. Note how the wing area has been reduced.
Adult wedge-tailed eagle in flight
The wingtip feathers are aerodynamically significant in that when deployed in eg slow flight, they reduce the drag which would otherwise be caused by vortices and local turbulence of airflow caused by the merging of air that has flowed over the wings (lower pressure) with air that has flowed under the wings (higher pressure). The winglets and related devices on the wing tips of modern passenger aircraft are designed to achieve the same reduction in drag. But the eagle can deploy or retract its wingtip technology instantly and at will according to the mode of flight it is in.
Adult wedge-tailed eagle in flight
Reconnaissance glide over the paddock. The head is down a little as the paddock is inspected from above.
Adult wedge-tailed eagle in flight
Those are the talons in the retracted fully closed position! They are a fearsome weapon. I have heard an account from an eyewitness in South Australia who saw a white-bellied sea eagle (slightly smaller than a wedge-tailed eagle) carry a small dead wallaby to a branch on a dead tree near a beach. The sea eagle left it there and took off (presumably intending to return promptly) only to have a wedge-tailed eagle claim it and fly off with the carcase.
Notice how the wings are being held in a manner that significantly reduces their total area – another useful capability for the flight requirements of this bird of prey.

Soaring

Adult wedge-tailed eagle in flight with wings fully spread
Compare the total area of the wings of the eagle in this photo with the wings on the bird in the previous photo. Greater wing area equals greater lift.
Adult wedge-tailed eagle in flight
Soaring effortlessly.
Adult wedge-tailed eagle in flight with underwings displayed in sunlight
Compare this photo to the one immediately below. In this shot the wingtip and tail feathers are fanned out to reduce drag as discussed earlier. The wedge-shaped tail is an aerodynamic control surface just like the elevator on an aircraft. Notice in the shot below how they are folded back to form a uniform smaller surface. It would be reasonable to guess that the bird in the shot below is flying faster than the bird in this photo.
Hang glider pilots considering taking off from a launch site (often an inland site) using the lift from wind blowing up a ridge or the side of a mountain, sometimes see eagles soaring overhead. If an eagle’s wing and tail feathers are as above, it can be assumed there is relatively light air (and light lift) where that eagle is soaring. However, if the wing tip feathers are not extended but streamlined, as shown below, the wind strength and lift are likely to be stronger. In strong wind/lift the eagle might also reduce the size of its wings by bringing them in closer to its body. This is useful information to a hang glider pilot about to fly.
Adult wedge-tailed eagle in flight
The majesty and beauty of the wedge-tailed eagle in full flight.

4 thoughts on “Wedge-tailed Eagles

  1. I love those tip feathers!
    I have had an eagle make a head-on attack at me. It closed to about 6 meters with it’s claws forward and pointing at me. I agressively waved my arms and shouted at it dived away. Nesting time near Mount Buffalo.

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  2. It’s an intimidating display isn’t it!
    Remember the Murmungee eagles Gilbo? I never had any close encounters with them, but I saw them quite a bit at a distance when I was flying there.

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  3. a marvelous blog John; I can well understand your affinity for this extraordinary bird when you were up there with him/her in your hang glider; perhaps much the same affinity as you had with the dolphin who kept you company in recent times!
    the photos also highlight the beautiful colours of the eagle which aren’t normally appreciated both because they are so far away and normally the sunlight isn’t shining on their undersurface.
    many thanks John
    cheers, Richard

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    1. Thanks Richard. The wedge-tailed eagle is indeed an extraordinary bird. They are so cagey, and being anywhere near one is a rare experience.
      But the lingering face to face encounter initiated by a wild dolphin during an ocean swim at Apollo Bay remains the most remarkable wildlife encounter I have experienced.
      Cheers, John

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