Talon-grappling eagles



There was a stiff breeze yesterday so I went out to watch for displaying raptors over some hills just outside Canberra - and I saw so much more than I expected. Four Wedge-tailed Eagles Aquila audax flew along the airspace at about my elevation on the hillside and two of them began to tumble down through the air, grappling their talons as they spun around and around.

These birds were all youngsters, i.e. fledged at least last year and not yet fully adult. This can be seen in the white base to their tails. Adults have dark tail coverts.

Although these birds have wing-spans of over two metres they showed that they are very agile and seemed to be in control of where they were at all times and in all directions. They would have to be or else they could have been seriously hurt.

They always grabbed the other bird's talons, never seeming to aim for anything else, or was it that each bird always fended off any strikes by the other.

They held each other by one and two talons, and I wondered if they ever drew blood from one another. Those talons are sharp and if they grasped the flesh of the other bird's foot, surely they could draw blood if they wanted to.

Then after only several seconds, the show was over. The birds let go and drifted apart. All while the third bird was watching from a few wing lengths away. And the fourth bird had drifted on along the ridge out of sight, mobbed by a trail of Australian Ravens, Australian Magpies and a Little Eagle.

Simon's crowdfund appeal















































Today I went into the Pozible website to add a pledge to Simon Cherriman's crowdfunding appeal. Then I noticed he has used one of my images of him climbing up to an eagle eyrie in Western Australia. That was taken last year and it was a great day out with a great guy. Simon is such an enthusiastic worker, and he works hard at a hard task. He deserves all the help we can give him. His appeal is for five satellite tags which he hopes to attach to wedge-tailed eagles, then follow their movements across Australia. This is all part of his PhD project. Do have a look at his appeal by following the following link:

https://pozible.com/project/wheres-wailitj

Than have a look at his websites too, to see what results can be gained from his eagle studies:

http://wedge-tailedeagletracking.blogspot.com.au/ 

and what other conservation work he does:

http://simoncherriman.com/Simon_Cherriman/Home.html

Wedge-tailed Eagles in the Perth Hills

A nine week old wedge-tailed eagle Aquila audax chick on its eyrie

I have been over in Western Australia for the past week helping Simon Cherriman ring/band and satellite-tag wedge-tailed eagle chicks for part of his PhD study on the species'  behavioural ecology. As this is Simon's study, I will only post a few snippets here to give a picture of the birds; how we ring them, their habitat and prey. To read more on Simon's work please visit his website at simoncherriman.blogspot.com.au.

The wedge-tailed eagles' habitat in the Perth Hills is mostly woodland with open patches of heath, so there is considerable cover for potential prey species. This is quite different from the more open landscape of central Australia, or the open hillsides which golden eagles live in in Scotland. There is a chick in an eyrie on the right of the photograph.

Simon measures the bill of a young wedge-tailed eagle.The sex of even young birds can be determined by the size of their bills and feet relative to their age.The females are larger. Bill Brown, who has also been helping Simon, holds the chick firmly but gently. He is well-accustomed to handling eagles as he has studied them in Tasmania.

This chick was about four weeks old. At this age the chicks are still mostly covered with white down, with only the first brown feathers opening from their quills on their wings and tail.

Simon pulls himself up by rope to reach an eagle eyrie. Although this looks easy with modern climbing equipment, Simon also makes it look easy because he is one of the best, probably the best, tree-climber I have seen, whether free-climbing or with technical aid.

The Perth Hills eagle study area is only about 30 km from the city centre of Perth, less from the airport. A Qantas flight passes overhead; there seemed to be a flight like this every few minutes while we were at this nest site.

The eagles appear to select the largest trees in their territory to nest in. Often these are remnants of the once widespread forest which would have been mostly of such grand trees as Jarrah Eucalyptus marginata, Marri E. calophylla and Wandoo E. wandoo. This nest was about 25 m from the ground, similar to most of the nests in the area.

While at the nest sites, we searched around the base of the nest trees and any other perches in neighbouring trees, looking for the remains of prey. At this nest site there were remains of a minimum of two Red-tailed Black Cockatoos, three Kookaburras, one Australian Magpie, one Australian Raven, twelve Shingle-back Lizards and two young Western Grey Kangaroos. These are all woodland species and the eagles possibly catch the lizards after watching from perches in the high trees. We do not know if the birds are be able to see the understorey where the shingle-backs live from high in the sky. However, Simon's study should reveal just how the eagles hunt, as the tags measure the height that the eagles fly at. So for now this is only my supposition.

The four week old chick is here placed in a bag ready to be lifted back into its eyrie. This bird has a standard numbered metal ring on its right leg and a coloured metal ring with a unique number on its left leg which is more easily read in the field or caught on camera.

Simon checks that a larger chick, which has been fitted with a satellite-tag, is alright before he abseiled back down out of the tree and we left the bird to settle down. Satellite-tracking of eagles and other birds is a well-established method for finding out where birds move to, revealing where they hunt and whether they migrate or wander nomadic-ally, and if so where to. The full details of this birds movements will be analysed by Simon as part of his study, but meanwhile a sample of the information he has collected from previously tagged eagles can be read on his website as linked above. And I am sure Simon will post snippets of information on this bird's movements as soon as he can.  

Fledging time

A full-grown Wedge-tailed Eagle chick stands on the edge of its eyrie

Yesterday, while out helping the with a university survey of woodland birds I was fortunate in being posted to a site near where a pair of Wedge-tailed Eagles have a nest. The single chick in the eyrie was well grown and ready to fly. And what a wonderful launch-pad from which to make one's first flight.

The eyrie is set high in a Blakely's Red Gum

Meanwhile the adults soared around overhead and up over the adjacent hilltop, dipping down to watch me as I walked on out of the area. No doubt they had been watching me all the time.

An adult flies overhead - keeping an eye on me

Wedge-tailed eagles

Yesterday while I out in the local woods, I heard grunting, muffled, barking calls. So I crept on quietly, expecting to find some mammal lurking in the shrubbery, but no. There were a pair a wedge-tailed eagles sitting in adjacent trees, calling to one another.

Eagles are normally quiet birds, or thought  to be, but I have been close to quite a few and have heard such muffled barking calls before; by golden and wedge-tailed eagles. They are probably thought to be quiet birds because people are seldom close enough to hear them.

These birds had obviously not long finished eating something as both their bills were red with blood. But it must have been a small prey item as their crops were not full. Adult Wedge-tailed eagles have a fine golden nape similar to the golden eagle, of Europe, Asia and North America. Their wedged tail forms a distinctive long pointed shape when the birds are perched.

This bird was probably the male as it was the smaller one, and its feet can be seen to be quite small in this photograph - females are larger and usually have large thick talons. The long central tail feathers droop down when in level flight. I often wonder on their purpose, do they help the birds steer through the canopy? For these are birds of open woodland and landscape with scattered trees.

There was no point in me hiding as both birds had obviously seen me. So I grabbed a few quick images as the male flew off through the trees - the nictitating membrane closing over his eyes as he squeezed through the branches.