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!
Wednesday, 23 December 2015
It's been a very busy past couple of months in the eagle tracking world, with the 'Where Do Wedgies Dare?' crowdfunding campaign taking up much of my time... but the good news is, the time I spent marketing paid off, and the campaign was successfully funded! This means a couple more eagles are set to be tracked in the New Year! As 2015 comes to a close, I can hardly believe it's been two-and-a-half years since this project began. The data gather so far has given us incredible insights into the Wedge-tailed Eagle's ecology, and as I prepare to (officially) commence my PhD at Murdoch University in 2016, there are no doubt even more exciting discoveries awaiting us! :-D
So, what has been happening in the lives of Wallu and Kururnpa?
Ladies first! If you've been following this blog closely, you might remember that, in October, our young girl returned from a long stint at her 'second home' at Roy Hill Station and was last recorded back in the vicinity of Lake Carnegie. Information from the WA Department of Agriculture and Food's Feral Herbivore Eradication team, who have regularly flown over this area in recent months, reveals there are several sites at Carnegie with surface water present, and many other Wedge-tails of various ages were recorded at this location. This explains why Kuyurnpa is spending time here: surface water means food, and other eagles means friends (birds of a feather flock together)! Similar patterns of young, non-breeding eagles 'living together' have been observed in the Golden Eagle (Aquila chrysaetos) by my Scottish pal Ewan Weston.
The above map shows Kuyurnpa's tracking data for the months of October and November. Interestingly, she flew across the north-eastern corner of Matuwa in late October, then actually came in and roosted less than 10 km from her natal nest on Matwua on 9th December. After a brief overnight stop, she winged her way a lazy 120 km east to roost north of Lake Carnegie again. (Remember you can click these maps to view large images).
Then her interest in her birthplace seemed to strengthen. A week later, Kuyu flew over her natal territory (shown approximately by the blue triangle) around 2 pm, drifting back to Wongawol Station (the easterly neighbour of Matuwa) to roost:
|Kuyurnpa's roosted on Wongawol Station on 16th December 2015.|
The next day (17th December), Kuyurnpa drifted south-west back onto Matuwa, and at 9 am was soaring at 1800 m above Lindsay Gordon Lagoon, less than 2 km south of Wallu's home range. By nightfall, after another day of floating high above the red dirt, she was roosting just 11 km south-east of her previous night's roost:
|Kuyurnpa's roost on 17th December is shown by the green dot in the centre of this map (click to enlarge).|
Kuyurnpa flew south and east on 18th December, then, keen for some more time on Matuwa, she headed north-west and spent the night of 19th December in a patch of tall Gidgee (Acacia pruinocarpa) trees not far north of the Lorna Glen homestead. This roost site was in the middle of four active breeding territories on Matuwa:
On 20th December, it was time for our girl to head back to Carnegie. This map shows the latest few days of tracking data, with all roosts being either on Wongawol or Carnegie.
You can 'watch' a slideshow of consecutive days showing Kuyurnpa's travels by clicking the first map and scrolling through to see additional points from each day.
What will the next week of tracking data show? Will this trend of homeward wanderings continue?
Now... what of Wallu?
|Wallu's tracking data for the past month, showing most roost sites near his nest, and the nearby rabbit warren.|
Having two large daughters to feed has no doubt kept him and mate Wurru very busy! Djentu and Minyma, which were photographed, colour-ringed and named in October, are now well and truly into their post-fledging period. I would love to have satellite-tagged them in October and be closely following their progress, but unfortunately we can only assume they are safe and well, and hope for a re-sighting of their '006' or '007' colour-rings one day in the future. Although the rain season should be approaching with the coming summer period, less than 30 mm has fallen at Matuwa in the past two months, meaning food could well be in short supply. Increasing daily temperatures, which we already know can kill juvenile eagles in the arid zone (see this post for more information), also add to the challenges these young birds face, and will no doubt claim more juvenile lives this season. Unless these birds are marked in some way, many of these deaths will go undetected, leaving us with little knowledge of the impact (positive or negative) to the Wedge-tail population.
As you can see in the above map, Wallu has remained focused around his 2015 nest site, with regular (almost daily) visits to one of the key rabbit warren hunting sites. Interestingly, though, we did record another short 'Wallu Walkabout', similar to the one recorded in January 2014, in the past five days:
On 18th and 19th December, Wallu's 9 am and midday GPS fixes showed him to be 12 and 17 km (respectively) south-east of his home-range. For an adult breeding eagle that we consider to be 'sedentary', the reasons for these forays are a mystery, but new research will always pose further questions, some of which we may never know the answer to. Perhaps more eagle tracking will help us find out!