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.  

Scottish summer summary

Walking over the tops - ptarmigan and dotterel habitat

It's now late July and I am back at the desk after my annual working tour of Scotland. Time to catch up with write ups and organise photographs. This was a quiet season for me as I had pinched a nerve in my spine in January and the sciatica is still hurting, curtailing any climbing, running and jumping. Fortunately a friend, Simon Cherriman, from Western Australia was also over in Scotland while I was there so we teamed up and I showed him around a few places and some of the special wildlife that abounds in such a small country.

While up on the high ground looking for ptarmigan we came across this Mountain Leveret

First of all we went and surveyed my long-term study site up in the hills for Ptarmigan. Their numbers vary between years following a cyclic pattern, and this year their numbers were low with only three pairs in the core area. But there were numerous Mountain Hares which was a welcome surprise. For these animals are being relentlessly killed on some estates managed for red grouse shooting in the belief that they carry parasite and act as a vector for disease in grouse, leading to fewer grouse to shoot. Such a selfish attitude at the cost of these animals which the majority of people visiting the Highlands in search of wildlife would so much like to see.

These three leverets were hiding in one form,
unusual behaviour as the mother usually leaves them in separate forms for safety 

A visit to the bird cliffs is always a tremendous experience
 - Simon rather enjoyed himself

Our next day passed quickly when we went to the sea-cliffs. The smell of guano mixed with the scent of Thrift had to be smelt to be appreciated, so so, different from anything else. 2014 was a splendid year for blossom of all sorts, but for now I'll concentrate on the animals. That day was definitely for the birds, thousands all around us and we must have fired off thousands of shots between us trying to capture the perfect shot of the birds in flight.

A Fulmar cruising past, most shots were out of focus, out of frame or wrongly exposed - hundreds of them

Simon adds colour-rings to a Redshank chick with Raymond Duncan

We spent most of our time based in the north-east and much of the field time ringing wader chicks with members of the Grampian Ringing Group, mainly with my brother Skitts, Ewan Weston and Raymond Duncan. Simon is a trainee ringer/bander in Australia, but has no experience of ringing wader chicks, or any other chicks for that matter. So he gained full-on intensive training from some of the most experienced bird ringers, not only in Scotland but the world.

A colour-ringed Lapwing chick

One of the jobs I had to do was find and fit Greenshank with geolocators as part of a study of their migration being organised by the Highland Ringing group. So we spent a couple of weeks in the far north doing that with Nick Christian and Brian Etheridge. That wasn't all we did there though, as there were so many other birds around us in that stunning landscape, but that has been covered in previous posts. And it would take too long to tell here.

Simon photographing newly hatched Greenshank chicks

The same Greenshank chicks

We ringed various birds during our travels, and as it was springtime most were chicks. They ranged from tiny Willow Warbler nestlings, Redstarts, Skylarks, Meadow Pipits, Pied wagtails, Common and Black-headed Gulls, Kestrels and Common Buzzards, etc. One rather different brood we ringed were Barn Owls which were in a nest in the roof space of an old ruined cottage. 

Simon checking the old cottage for the Barn Owl nest, and Jackdaws

There were five owlets squeezed between the ceiling and the roof

But it was when we had trees to climb that Simon earned his living. As I had hurt my back I was reluctant to climb some of the trees to reach various nests, but Simon is a superb tree-climber, probably the best I have seen. He had timed his trip to Scotland perfectly. I helped him and he helped me - all happy.

Predator in his natural habitat
 - a similarity noted by Mick Marquiss as Simon skipped up a tree
 so like the film character with his dreadlocks and camouflaged gear

Simon, like all of us who climb these trees, really enjoyed the thrill
 and atmosphere of climbing ancient Scots Pines

We helped Skitts and Ewan ring Golden Eagle chicks at various nest sites which they monitor annually. Ewan and Simon would climb the trees, lower the chicks in a bag down to the ground, where they were ringed and measured safely, then they we would pass them back up. Some of these nests are over a hundred years old, in trees that are several hundred if not thousands of years old. And some of these eyries are big, really big. Who wouldn't be impressed by such an experience.

Simon nears a Golden Eagle eyrie in the crown of a Scots Pine
- even he, at two metres tall was dwarfed by the eyrie

Simon studies Wedge-tailed Eagles in Western Australia, so he was perfectly at home and adept at handling the Golden Eaglets. Although they can be big strong birds and they can be in a potentially precarious setting, mixing tender careful handling with confidence ensured slick procedure.

Talking to eaglets always helps - it might not calm the the birds,
but it does calm the handler and helps the work go efficiently 

And that was what I did in Scotland 2014, well a little bit of it, there were also Arctic Terns, Golden Plover, Dunlin, Woodcock, Sparrowhawks and....  Thanks for all the help Simon.