Friday, 16 December 2016
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
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), Yirrabiddi (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
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
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
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?!
Friday, 21 October 2016
This is the beautiful Goonta, the latest magnificent Wedge-tailed Eagle to join our family of satellite-tracked birds. Goonta was banded last week, and after receiving approval to commence the fieldwork component of my PhD a few days ago, we returned to her nest today to fit her with a harness-mounted PTT.
|Bill Brown prepares to place Goonta in a handling bag after her PTT has been attached.|
Using a new attachment procedure that I recently learned from my wonderful raptor-researching friends in Scotland, I fitted the transmitter to the eagle's back using a Teflon harness, which is stitched on at the front creating a 'weak link' that will eventually disintegrate. The transmitter is light (70 g) and makes up only a very small proportion of the bird's total weight (2.5 kg). It was wonderful to be able to share this experience with Bill, and also with a good family friend David Ryder, who I have known since very early on in my ornithological career (about 27 years!), and who has also been volunteering to help with this year's research.
After snapping a few photos, Goonta was then placed back on her nest, and this time she stood and watched us carefully, probably wondering if we would be back to visit again. Other than to spy her from a distance and make sure it is behaving normally, we won't need to disturb her again - the monitoring will now be done via a remote satellite connection!
|The PTT is just visible on Goonta's back.|
It is hard to believe that 3 years has passed since we tagged the previous juvenile female wedgie Kuyurnpa, who has now travelled over 10 000 km each year since. Time - just like these amazing birds - flies fast! I can't wait to see where Goonta goes!
|Goonta watches the sun set from her outback eyrie. It won't be long before she'll by flying towards it.|
Tuesday, 18 October 2016
Having just completed assessing the Matuwa Wallu-wurru / Wedge-tailed Eagle population's breeding activity for 2016, it was evident that the past season had been a dry one indeed. Only three of the 35 breeding pairs (less than 10%) produced chicks, compared to five pairs last year, and five the year before. Such productivity is very low but probably quite normal in the arid zone where these top order predators only thrive in occasional productive years. It is also an indicator that ecosystem productivity was low, because only three territories had enough prey for the resident adults to nest, incubate, hatch and rear chicks.
|A typical Wallu-wurru nest from the 2016 breeding season, being partially lined but with no signs of breeding.|
The majority of eagle territories contained one nest which had signs of preliminary nesting, being partially or fully lined, but there was no evidence of further breeding activity. Together with the tracking data from our breeding adults, these signs of continued visitation to nests show the long-term attachment to territory that Wedge-tails display, first suggested by CSIRO research in the 1970's. Incidentally we did observe adult pairs perching on their nest, or soaring nearby, and while assessing the 100 or so nests from a helicopter, we were able to get some great views of these magnificent birds in flight.
|An adult female Wedge-tailed Eagle banks in front of the chopper. Note the bird's barred primary feathers which suggest she has not quite reached full adult plumage.|
Despite most nests being empty, one that we visited did have a large, healthy juvenile aged about 8 weeks. The discovery of this eaglet created an opportunity for what was a definite highlight of this recent trip. Martu Elders (who have kindly continued to endorse this ongoing eagle research on their land) and children from the local Wiluna Remote Community School were on country to take part in educational activities, so a small group visited the nest with us to learn about ringing/banding research.
After hand-catching the eagle on the nest, it was lowered to the floor in a handling bag for processing. I was very fortunate to have Bill Brown, a Wedge-tailed Eagle researcher and experienced raptor handler from Tasmania, volunteering with me to help. His skills in holding the bird and keeping it calm during processing were fantastic and allowed the procedure to go ahead quickly and smoothly.
The Martu Elders, school teachers and children, and a group of bird-banding researchers led by my friend and colleague Neil Hamilton, all watched on as we explained the process of fitting metal and coloured leg-rings to allow identification of the birds, taking measurements, and the overall implications of this research.
|Bill Brown removes the eagle from the handling bag.|
Once banding and measuring was complete, the eagle was returned to its nest, where it sat quietly and bobbed down to lay flat on the nest cavity. This behaviour is typical for nestlings that want to remain hidden in low, outback eyries. We then all gathered below the Wallu-wurru nest to take a group photograph, during which time the eagle remained quiet. This gave Rita Cutter (one of the Martu women elders) an idea of a name for the bird: Goonta, which is a Martu word meaning 'shy' or 'quiet'. A perfect fit for this female eagle.
While walking back to the car, the whole experience began to sink in. It brought tears to my eyes to able to be on country with this land's (and the world's!) oldest indigenous culture, people who have for thousands of years lived in a sustainable relationship with the country out here. What an absolute privilege to have their permission to conduct ongoing work to find out more about these charismatic birds of prey, in what I hope can continue to be a ongoing, collaborate venture to engage with this amazing landscape.
The Kalgoorlie Miner reported a great article on this event, which you can read here. Also, the school children have since created some wonderful videos documenting their experiences while on country. You can view these, as well as a selection of photos, at the school's Facebook page.
Sunday, 24 July 2016
After spending the past 3 weeks at Roy Hill, Kuyurnpa has again drifted southwards back towards Matuwa, this time taking a slightly 'western' (compared with previous trips) route which took in parts of the Great Northern Highway. As you can see in the above map, there are three points at which her journey overlapped with WA's main artery north. Two of these were just 'crossings' where our eagle soared high over the thin strip of bitumen and kept flying, but the third and southern-most point shows Kuyurnpa spending several hours at ground level near the road, then roosting for the night 200 m west of it, about 100 km north of Meekatharra. A likely explanation is that she was attracted to feed on roadkill, a common activity for many young, nomadic eagles like Kuyurnpa. This behaviour occurred after a 420 km journey from Roy Hill. Most travellers I know don't even last half this distance before they are tempted to stop at the nearest roadhouse for some 'roo jerky'... then again, most travellers I know are not eagles!!
Turning east again, Kuyurnpa spent the next two days completing her 640 km trip back to Matuwa. Her homeland was then the focus for two-and-a-half weeks, but on 22nd July she completed a huge northern loop by flying 430 km north to Roy Hill again, a total return distance of ~1500 kms! Here's a map showing those movements:
Although Matuwa only kept her attention for 17 days, and the above map shows a few concentrated GPS fixes which do not seem to indicate much movement, this initial glance is misleading. Let's zoom in a bit:
The green dots on the top left and top right corners of the above map show GPS points recorded on Kuyurnpa's inward (4th July) and outward (21st July) paths to the Matuwa area, respectively. It's really interesting to look closer and see the exploratory behaviour during her stay. The large cluster of points near the south-east corner of Matuwa, where Kuyurnpa spent several days at a time exploring a (possibly vacant) territory are actually broken up by a few flights back and forth to roosts in the north (on Kurra-Kurra, the Martu Aboriginal property adjoining Matuwa). Together with some loops to the east and west (including one flight over her natal territory, shown by the blue triangle), the distance our girl has travelled while 'not really moving much' is over 500 kms! This means the loop we saw above on the first map is actually 2000 km, a miraculous achievement by Kuyurnpa and a demonstration of the sheer ease with which this magnificent eagle species can cover ground!
Sunday, 26 June 2016
Although I'm currently away in Scotland gaining experience in Golden Eagle research, which will be an enormous help for my future eagle studies in Australia, I've been closely monitoring the movements of our two sat-tagged 'wedgies' Wallu and Kuyurnpa. As you would've read recently, Kuyu spent much of late 2015 and the early part of 2016 in the vicinity of Matuwa, wandering the lakes of the Carnegie area and frequently 'ducking over' (or, more accurately, 'eagling' over!!) to visit habitats close to her natal territory. In the past month, however, she has headed northward again, embarking for her other favourite haunt at Roy Hill, making one overnight stop to complete the ~350 km journey there on 3rd June.
Zooming in on the above map, you can see more detail of Kuyurnpa's recent movement in relation to the major landforms (the pale grey sections are rocky ironstone 'plateau's' with Porcupine Grass (Triodia sp.), and the red 'sandy' looking areas are lowlands, with the large reddish section to the west being the well-known Fortescue Marsh):
We can now glance back to the same map and look at our young girl's movements between March and June 2015:
These datapoints indicate Kuyurnpa recently revisited many of the same areas she had been to before, perhaps even using the same roost sites, places she has probably stored inside her internal 'black box'!
Now to Wallu...
Compared with this juvenile female, our adult male has continued his much more sedentary behaviour, but of late we have seen him leave his home range on a number of occasions, something which in the last 3 years has only been recorded once before. After spending the nights of 9th & 11th June a kilometre or so outside of his home range (southern- and western-most GPS fixes in the above **map), Wallu then travelled way to the north-east and spent the night of 10th July about 50 km away, before heading 'home' to roost the next day. Then, on 20th July, he moved away east and again spent the night 50 km away:
At this stage I cannot offer any explanation for these unusual movements - perhaps food is short at home, or there is competition for mates? Sometimes I wish I was there on board the PTT to actually SEE what was going on! The main thing is, Wallu is alive and well, and continuing to generate very interesting findings.
Thanks for tuning in everyone! I'll post more updates from arid Western Australia (via not-so-arid Scotland!) soon :)
**(Just to keep you up to scratch with things, the black polygons shown on the above map are the approximate 'boundaries' (I use that term very loosely) to other adult breeding territories, something I've been working on lately. The blue triangle in the fenced enclosure, where our late Gidjee lived, and the green line denotes the boundary between the Murchison and Gascoyne IBRA regions.)
Wednesday, 18 May 2016
Where are the eagles now!? If you checked in just over a month ago, you would have seen that Wallu was still at home, and Kuyurnpa was loitering around her well-known haunt to the north of Lake Carnegie. Not much has changed in the past 6 weeks, except to say that our young girl's homing behaviour has continued, with regular visits to Matuwa. She has spent 6 nights roosting on our study area, which averages one per week, a slight increase in regularity since the start of 2016. Spending so much time looking at Matuwa on a mapping system, which makes this huge area appear tiny, often makes me under-appreciate the scale of this immature eagle's regular movements! It still amazes me that one night she can roost on Matuwa, and the next she can be way out near Carnegie again, almost 100 km away. The joys of being able to fly!
Monday, 4 April 2016
The 2016 autumnal equinox has now passed (this occurred on 20th March), signalling the beginning of a new 'eagle year'. This means the breeding behaviour of territorial adults will start to increase, particularly in the form of display flights, and any of last season's offspring still 'at home' will probably have commenced dispersal by now. Kuyurnpa began this new phase in her life on 29th March, just over 2 years ago.
Checking in on the progress of our two tagged eagles Wallu and Kuyurnpa again has revealed some very interesting updates. Kuyurnpa's 'homing' behaviour that we've seen over the last few months seems to have continued, with visits to Matuwa or nearby being recorded every 10 days or so (see the above map). One GPS fix from 3pm on 27th February shows her flying 700m above the ground only 8km north-west of the nest on which she hatched about 960 days ago! For most of the time, however, Kuyurnpa has been occupying a smaller 'home range' on the northern edge of Lake Carnegie, an area about 50km across. This is a place she has frequented quite a bit in the past year or so, perhaps in relation to some of the wetlands containing water (35mm of rain fell here at the start of February).
Not much has changed with Wallu! You can see the cluster of red dots on the above map which tell us he's remained within his home range. Daily activities involving high daytime soaring and morning/evening visits to favourite foraging areas are also consistent with previous tracking data.
What will happen next? Let's keep on tracking to find out :)
Monday, 22 February 2016
Just like our mighty Wedge-tails, this year is flying fast! As January merged into February, Kuyurnpa continued her trend of popping back to Matuwa on occasion, and gradually consolidated her use of the northern and eastern shores of the enormous Lake Carnegie. The last time she spent so much time in this area was back in October 2014, when she crossed Matuwa after a long stint at Roy Hill and spent 3 weeks along the southern edge of lake Carnegie.
Then, to scratch some apparently very itchy talons, Kuyurnpa decided to spend the second week of February completing a 6 day, ~1100km loop towards Kalgoorlie, west and north to Menzies and Leonora, and back north to Wiluna. The distance between her roost sites on the embarking date (11th February) was ~300km, and on 16th February, she flew 200km in one day to roost just south of the Matuwa boundary. This journey took her further south-west than she has ever travelled! I am very interested to know whether this Arid Zone-born eagle will ever enter the Mediterranean Zone (the south-west corner of WA) - her most recent journey certainly had her coming close! We'll only find out with more eagle tracking!
|Kuyurnpa's recent journey saw her roost just 600km east north-east of Perth.|
Monday, 4 January 2016
In the two and a half years we have spent keeping a detailed eye on Wallu's movements, he has not left the fixed and precisely bounded piece of Matuwa that comprises his home range. Despite occasional daily wanderings of up to 60 km, Wallu has for more than 900 consecutive days roosted at home. Today we recorded a break in that trend - Wallu decided to wander ~35 km east and spend the night in a small patch of trees alongside a creek-line half way between the Matuwa boundary and the Gunbarrel Highway. This spot is shown by the eastern-most red dot on the above map (click to enlarge). The next day he was back home again, ending the next few days at well-used roost sites. Are his two daughters Djentu and Minyma still in Wallu and Wurru's territory? I would love to know!
So what are all the green dots!? You might remember from previous posts (scroll down) that green is the colour I've used for our two-and-a-half-year-old girl Kuyurnpa. Her behaviour continues to be very interesting, with the contraction back towards her natal territory observed in the past few weeks carrying on. As you can see on the above map, which shows the past month of tracking data, Kuyurnpa has actually roosted on Matuwa for two nights (she even saw the New Year in just 10 km north of her natal territory!), and continues to regularly wander between the property and the neighbouring Wongawol and Carnegie stations to the east and north. This behaviour is almost identical to that observed for a young male Spanish Golden Eagle (Aquila chrysaetos), who contracted his wanderings back to within 20 km of his natal nest in his third year. I am so curious and excited about what Kuyurnpa will do in the next 12 months - will she settle down and breed? Let's keep tracking to find out!