Monday, 20 February 2017

Phase Three


Our most recently satellite-tagged Walluwurru Malya has continued to spread his wings and now appears to be ranging over most of his parents' territory, which, as you saw last time, is the 'neighbouring property' of our beautiful adult male Wallu. These two eagle territories are shown in red and blue on the above map. During the last few weeks, our 'teenage' wanderer Kuyurnpa drifted in from the east, homing in on a long-range (~300 km) exploratory loop to spend a single night roosting at Matuwa. This creates an exciting opportunity to summarise our three arid-zone eagles currently being satellite-tracked:

  • Wallu, a ~10 year-old mature adult who remains sedentary in a fixed home range, where he has stayed for 3.5+ years;
  • Kuyurnpa, a 4th year immature who is still in her dispersal/wandering phase, moving freely through the arid interior with occasional 'return visits' to her natal territory;
  • Malya, a 1st year juvenile currently still in the post-fledging period in his natal territory, where he will be dependent on his parents until the dispersal phase begins in several months.

These birds represent the three different stages a Wedge-tailed Eagle's undergoes during its life, and it is exciting to be monitoring one arid-born eagle from each stage! I am super excited to know when Malya will begin dispersal, and when (if!?) Kuyurnpa will settle in a breeding territory. Let's keep on tracking and find out!

Sunday, 5 February 2017

Spread those Wings


It is now almost 2 months since Malya fledged, and his progress has been amazing! Initial movements of 50 - 100 m from the nest (shown by the pink pin on the above map) continued over the first fortnight, and soon the young male eagle was roosting in a tall tree just over 1 km from the eyrie (which, coincidentally, I had climbed the day of his tagging, to photograph an oncoming thunderstorm!).

These short bursts were rapidly replaced by longer flights of over 100 m, and in the last month of tracking, Malya has spread his wings widely and travelled across an area with a radius of just over 6 km. He has also been recorded soaring to great heights, reaching altitudes of over 2000 m on some of the warmer days.

Malya's parents' territory happens to be adjacent to that of Wallu, our 'founding member' of the eagle tracking family, and zooming out provides a comparison of the 2 birds' movements during the past 8 weeks. The dark, diagonal line shown on the below map (click to enlarge) is a ridge running north-west to south-east, a landform which appears to form the northern boundary of Wallu's territory. So far these two birds have not overlapped, but it is important to keep in mind a juvenile like Malya may be tolerated 'intruding' on another adult's patch, unlike one of his parents. It is great to be able to have this context of two arid-zone wedgies

Friday, 16 December 2016

RIP Goonta


I write this with mixed feelings - still thrilled with the addition of a second sat-tagged eagle to the eagle tracking project, but saddened by the bad news that was confirmed today. Bruce and Kaye Withnell, the caretakers at Matuwa, rang me to confirm that Goonta was recovered dead, found lying on her side in an open patch of spinifex shrubland, not far from her natal nest. This juvenile wedge-tail fledged only a month ago and had started to make longer movements away from her nest, as anticipated. At this stage we have no idea what the cause of death was, but fortunately there was no evidence Goonta's PTT had interfered with normal movement, or that the harness had caught on any vegetation. You can see in the above photo her feet are spread open and wings drooped, suggesting she died perched on the ground, probably in a very hot position. Being still dependent on her parents for food, Goonta's death may be an indicator of their capacity to provide prey, or suggest there was a sudden shortage of prey nearby, although the latter reason seems unlikely given this territory overlaps with the fenced enclosure containing a high density of boodies and bandicoots. Whatever the cause of death, the trend of low productivity and high mortality in an arid-zone population, as previous research has shown, seems to be continuing.


*POST SCRIPT. A postmortem carried out by Murdoch University in January 2017 found no conclusive evidence of a cause of death.

Wednesday, 14 December 2016

Five Noongar Birds


So far the Wedge-tailed Eagle tracking project has been set entirely on Martu Country, and we have made some wonderful discoveries about the ecology of arid-zone eagles residing in this vast landscape. But my dream to satellite-track Wedge-tails actually began a long time ago and a long way south, on Noongar Country, so since starting research here in the desert, I've been working towards adding a south-west WA site to the project. Commencing a PhD project through Murdoch University in July this year created the opportunity to do just that, and part of my research proposal is to compare the juvenile dispersal behaviour of eagles born at Matuwa with those raised in my homeland, the Perth Hills. Today I'm pleased to announce the Perth region is now officially on the wedgie-tracking map, with the fifth and final (for 2016!) Perth Hills eagle being satellite-tagged. This bird was named 'Walyunga' after the very special National Park in which it was born, an important cultural area for ancient Noongar people on whose land I am privileged to be able to live and work.

Stuart Broadley holds the eagle while its PTT is attached.
Walyunga on his eyrie after satellite-tagging. The PTT aerial is visible protruding from his back.

I am especially grateful to the volunteers who accompanied me to assist with today's satellite-tagging fieldwork, especially Andrea Williams from the Goldfields Environmental Management Group (GEMG), who currently sponsor field operations for the Matuwa eagle research, and Paul Udinga, the senior Walyunga National Park ranger, who has assisted with monitoring of and access to this nest. Thanks also to Heidi Dougherty from the Shire of Mundaring, Parks and Wildlife volunteer Ken Suckling, and my friend and fellow eagle enthusiast Stuart Broadley from the Philippine Eagle Foundation, for helping make this thrilling afternoon a great success! It was a wonderful day to be out bush!


Walyunga (a male) joins Wailitj (female), Yurrabiddi (female - pictured at the top of this post), Kala (male) and Korung (female), all of whom were tagged as juveniles in October and November this year. You can read more about the individual tagging events pertaining to each bird on my personal iNSiGHT News blog. The below map shows the locations of each of these birds' natal territories, shown from north to south in the order the birds are listed above. We anticipate these juvenile eagles will remain 'at home' for the next 3-4 months, then begin dispersing... somewhere! This will be the first time Wedge-tails from a Mediterranean climate have been tracked during this early phase of their life. Where will these wedgies dare? Keep watching to find out!

Monday, 12 December 2016

Meet Malya


After a long drive out from Perth to Matuwa yesterday and a few hours sleep, it was exciting to wake up before sunrise and head out to a Walluwurru / Wedge-tailed Eagle nest that caretaker Bruce Withnell had kindly been keeping an eye on for me. I last visited it during the research trip in October with Martu women and volunteers to band a month-old nestling, pictured above, who had been well fed on a recently caught Paarnka / Yellow-spotted Monitor (Varanus panoptes).


Bruce and I, along with my friend David Ryder who generously provided a vehicle for the trip, and fellow ornithologists Tegan Douglas and Neil Hamilton, got to the nest just as the clouds were turning gold in the morning rays, and we were thrilled to see a large eaglet perched on a branch just above the nest. As I scaled the tree to capture the juvenile eagle, which, as Bruce had reported over the past few weeks, was now fully feathered and close to fledging, it launched and sailed on a short glide to the ground. Neil managed to secure it quickly, and carefully holding the talons, calmly carried it back to below the nest, where we had our get set up.


With Neil holding the bird, I set about attaching a satellite-transmitter to it's back. It is always wonderful seeing juvenile eagles up close, an experience that allows one to observe the detail on their beautiful faces. As with many of the Matuwa-born eagles I've observed in the past 5 years, this one had quite reddish plumage. Some eaglets I've seen in the Perth Hills are similar in colour, while others have quite blonde feathers, particularly on the nape. Such variation is yet another fascinating and intriguing feature of these magnificent birds. 

With PTT sitting perfectly between the shoulder blades, the eagle is ready to be returned to his nest.

When close to fledging at approximately 80 days of age, it is normally very easy to tell the sex of eagle nestlings, with females being noticeably larger, having a broad footspan and being longer in the skull. However, this bird had a complex combination - it's footspan was tiny and very 'male-sized', but the head appeared to be extremely elongated, like a female. Taking the weight and overall appearance into consideration, my feeling is that this bird is a male, but we will be able to confirm the sex using DNA from the feather sample taken. While this research is primarily focused on movement ecology, we are recording morphometrics of all birds handled, which will also broaden current knowledge of the size variation in eagle nestlings of each sex (most previous research on wedge-tails has focused on full-grown immature or adult birds). 

With harness attached, it was time to put the eagle back.


To ensure he did not become unnecessarily spooked by my presence, I descended the tree straight after placing the young eagle gently back on the eyrie, and it was wonderful to watch him confidently hop back up and onto the limb on which he was perching when we arrived.


The next morning, David and I revisited the nest site to check on the newest member of the eagle-tracking family, and found the eyrie was empty. He had fledged! It felt very exciting to know we had tagged this eagle just in time to accompany him on the start of a remarkable journey!

On the way back to Perth, we called in to Wiluna Remote Community School where I was excited to catch up with teacher Debbie and many of the children who came to Matuwa during our research trip back in October. I was keen to give them all an update on the recent tagging adventure, and ask the children if they would like to name the eagle we'd just sat-tagged. After a short talk I left an image of the bird on the screen, and one of the girls instantly said the world 'Malya', which she told me means 'cool' or 'awesome' in Martu. Debbie and the class had a quick chat amongst themselves and with Rita Cutter, a Martu elder, and all agreed this was the perfect name. So, welcome Malya! We are excited to be flying with you, high above Martu Country.

Celebrating the naming of Malya with Rita Cutter (centre) and children from the Wiluna School.

Wednesday, 30 November 2016

Goonta's Going!


After fledging on 16th November and spending most of the following 10 days roosting in a patch of tall trees near her nest, Goonta has now started to make larger movements, with the latest exciting map (downloaded today - click to enlarge) showing her gradually carving a path eastwards. The most recent fix we received is nearly 1 km east of her nest, which is quite a good effort for a bird that hasn't been on the wing long! I am super excited to monitor this young desert eagle's progress over the coming weeks!

Monday, 28 November 2016

Close on Matuwa


It's been a while since we had an update from our two longest-tracked eagles, Wallu and Kuyurnpa, but I'm pleased to report all is well with both! Kuyurnpa has been spending the past few months wandering the Carnegie Lakes system and floating over Matuwa on occasion, and Wallu has remained 'at home' as normal. Today, Kuyurnpa flew in from the far east and roosted almost on Wallu's home range, as shown in the above map. This is the closest these birds have been since April this year, when Kuyu passed right over Wallu's nest. How long will she stay on Matuwa this time?!