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.  

Garden quenda

A Quenda, Southern Brown Bandicoot Isoodon obesulus 

I am over in Perth, Western Australia for ten days helping Simon Cherriman monitor, ring and tag wedge-tailed eagles, more of that in a later post, for now here are a few images of the local wildlife, starting with a sample from the garden.

Simon sets off down the front drive to hang some nest boxes for black cockatoos around a local school

The house sits in a large rural residential block with a mix of local and introduced flora. And Simon has put several nest-boxes up for various parrot species, owls and ducks, as most of the trees are too young to have natural holes large enough for these large birds.

Morning light on a corner of the garden

The mix of water in the dams, boxes to nest in and grass to eat make the garden a great breeding area for Australian Wood Ducks Chenonetta jubata.

Gum trees reflected on the lower dam

A pair of Australian Wood Ducks with their brood of three well-grown ducklings

There are numerous nectar-bearing shrubs such as bottlebrushes Callistemon spp and these are full of honeyeaters feeding from the flowers.

A New Holland Honeyeater Phylidonyris novaehollandiae

There are four species of honeyeater in the garden, all fighting and chasing one another for the nectar: Red Wattlebirds Anthochaera carunculata are top of the hierarchy as they are the largest, then there are the Western Wattlebirds A. lunulata, the New Holland Honeyeaters and finally the Western Spinebills Acanthorhynchus superciliosus 

A Western Wattlebird feeding on a bottlebrush bush

My morning started with a great view of a Quenda exploring the front porch.These are charming little marsupials, and a small population live in the garden, foraging in the leaf litter mostly at night and sleeping in nests under the litter during the middle of the day.

An adult male quenda on the front doormat

When I went out for a walk around the garden in the early morning, a young quenda came right by me and began foraging in the mulch for invertebrates.

They burrow their snouts right under the litter, sniffing and probing for food

The youngster was quite unafraid of me as I squatted down and watched it going about its business.

But I had to be quick with the camera as the little quenda could move quickly when it decided to. It was good to see a native animal thriving in a garden setting. The conditions are good for them; they have food and shelter, and it is a cat-free zone, so the population is probably exporting animals out to the surrounding native bushland. What a terrific wildlife garden.

 

Sundews and orchids

Pale Sundew Drosera peltata

 It is well into spring now in Canberra and I have been running around trying to keep up with the wildlife as the breeding and season flies on. So, I have not had time to upload many posts, there is just so much to do, see and record. As there has been so much rain, the wild flowers are all blooming well. One species that is normally quiet reluctant to flower and tends to grow on moist banks or in gullies is the Pale Sundew, and I have never seen it flower so well as this season. There are large stands of it in places and all the plants in the groups are flowering.

Insects trapped by the sticky tips  on the specialised sundew leaves - adapted to digest nutrients from the insects bodies 

The tiny petals on the flowers do not seem to last long, and flies were the main pollinators this day. Their individual flowers were insignificant to our eyes, but on-mass they were unusually spectacular, dotting the greenery on the floor of the forest.

The sundews growing on this bank shone like fireworks in the backlight

The backlight also picked out the dramatic drooping flowers of the Nodding Greenhood orchids growing nearby. This orchid is listed as rare/threatened in the Canberra area, but on this shady bank there are scores of plants. Perhaps the species would thrive better if it grew as more individuals or smaller groups. I know of a few other colonies, but not many.

Nodding Greenhood Pterostylis nutans

And while I was photographing these spectacular plants, a pair of Tawny Frogmouths were looking down on me . The male from the nest and the female from her daytime roost. Well, it was while I was checking on the progress of this pair that I found the flowers.

The male frogmouth on the nest during the daytime

Frogmouths are so difficult to find, that one has to look really carefully and pay attention to everything in the forest. Some clues to the birds' presence, such as their droppings, lie on the ground. So my eyes are up, down, all over the place, checking everything for signs. If you are looking for frogmouths, you are likely to see everything else.

The female frogmouth in her roost

   

Heads or Tails

Not the head, but the tail of a Shingleback

The local reptiles are beginning to show as Spring moves on and the days warm up. There have been rustles in the garden when the little skinks scurried for cover as I passed and I saw my first Shingleback Tiliqua rugosa in the bush a few days ago. These are a species of blue-tongue skink, one of the larger types of lizards in south-east Australia, and as they are slow moving and terrestrial, they need a few tricks for defence from predators.

A Shingleback out in the open, seen from above - a raptor's eye view. Which is the head end?

Their main adaptation for protection from predators is deception by camouflage. They are a simple long brown, grey shape that mimics a stick or small broken branch lying on ground. This probablly hides them from aerial predators such as, in our area, Little and Wedge-tailed Eagles. Then if a predator ventures closer, it might be tricked into attacking the tail rather than the head end of the Shingleback because the tail mimics the form of the head. The skink's next strategy when touched is to turn itself around into a tight U-shape, open its mouth wide open, and thrust out its large blue tongue - a shock or startle defence. Blue is such an unusual colour in animals, that it probably has a particularly high startle effect. However, this startle is mostly bluff as the Shingleback has little else to defend itself. They are mostly vegetarian, with a fondness for soft flowers, so they do not have large or sharp teeth or claws.

When seen from ground level, the eyes make the head more obvious

I would like to see their defence in action against a predator, although at the same time would rather not as I like shinglebacks and would not like to see one hurt. They are such quiet non-aggressive animals. Perhaps the evidence of me seeing them quite frequently when out in the bush is enough to prove their defence's efficiency.

Shinglebacks are quiet and easily overlooked, but their slow lifestyle makes them easy prey for their main predators,
which these days are the introduced fox and domestic cat 

See the previous posts on shinglebacks listed on the right for more information on them, including a shot of that blue tongue.

Bathing in the creek

Thigh-deep water is just the perfect depth for birds to bathe in and have a good splash around.

The wet Spring in Canberra continues, and the number of birds visiting the garden pond for a drink or bath has dropped dramatically. Few birds are using it, mostly the local residents such as the Red Wattlebird, Superb Fairy-wrens and the Crested Pigeons. When it is hot and dry, birds from all around seem to drop in, but the ground in the nearby nature reserve, at the top of our street, is saturated with puddles lying all over the place. The dams are full and the water courses are all running and bubbling. So there is no need for the bush birds to go elsewhere to seek water.

The rosellas could immerse their bellies with a gentle dip, their tail lies softly on the surface and they can jump straight into the air and fly off if any predator approaches while they are otherwise potentially vulnerable. Consider this when you set up a bird bath in your garden. Provide gradual edges, not steep edges for birds with different leg-lengths.

I heard these two Crimson Rosellas splashing when I was out walking through the woods the other day. The creek line they were in is usually a dry ditch for most of the year. This Spring it has been full of water every day. It wasn't the perfect picture opportunity, with branches obscuring the view - which was a probable reason why the birds were using that spot. However, as they were happy to bathe a few metres from me I grabbed a few shots.

Overhanging or nearby branches are valuable assets as they provide cover from predators
 and safe perches for the birds before and after entering the water. 

The rosellas were so confiding in me that they flew up onto a perch to dry their feathers while I stood watching. Although they did keep watching me too, just in case I was a predator.

The water ran off the birds backs, like snow-melt running off a well waxed snowboard. 

The waterproofing on the birds' feathers is provided by the preen gland (uropygial gland) which is below the feathers at the base of the tail, just about at the bottom the bird's back in the image above. Birds collect oil from the gland with their bills and spread it over all their feathers when they preen. Not all species of birds have this gland, some rely on powder down for a similar purpose, but more on that in a later post. For now, just look at how well the oil system works as the water runs off the tip of this rosella's tail.

   
Meanwhile the rain is hammering down again...........