Djentu and Minyma

Yesterday I had the privilege of spending some time on country with three local Aboriginal girls from Wiluna, whose teachers Chris and Anni had arranged a school adventure to enable students to learn about researching Wallu-wurru (Wedge-tailed Eagle) ecology at Matuwa. I began by drawing in the sand a story about our tagged adult male wedgie Wallu, showing his home-range and nest sites, and described the successful nest I'd visited last week. We then set off into the bush to check Wallu's nest, in the hope we would get some nice views of his two daughters.

When we reached the nest tree, I was very happy to spend time showing everyone the evidence used to determine that an eagle nest is active - lots of 'whitewash' (scats), fresh eucalypt sprigs dropped from the nest cavity's lining, and the remains of prey items delivered in the past few days. I climbed the nest to check on the juvenile eagles' progress, and was pleased to see them both standing tall on their sturdy legs, with the blue colour rings showing nicely. 

It was a marvelous view looking down from the nest tree and seeing the students and their teachers talking happily :)

When I descended to show the group close-up photos, the students asked if the two eagle chicks had names, to which I replied "No, we haven't given them any." Then something amazing happened: the girls said "Can we give them names?" This excited me greatly and I of course agreed. After a short discussion, the girls decided on 'Djentu' (pronounced 'jen-doo', which means 'sun') for the older chick, and 'minyma' ('min-muh') which is a local Martu translation for 'girl'.

Djentu (left) and Minyma stand proud and tall on their parents' Wallu and Wurru's eyrie. These two juvenile eagles are now about 10 weeks old and are about 2 weeks away from fledging.

Although they are not being satellite-tracked, Djentu and Minyma still have unique identification numbers on their colour rings, so provided these can be read if the birds are resighted, we will be able to determine who is who!

The bulge in Minyma's neck indicates a full crop, an encouraging sign of a recent feed.

Naming ceremony complete, it was then time to walk back to the car, with special thoughts of the eagles' new names in mind, and a magic outback sunset to look back at.
 

'Twin' Girls!

After a short walk through the Mulga scrub today, I was super excited to spy Wallu perched at the top of a tall Cue York Gum, watching my every move. He stayed for only a few minutes, just long enough for me to snap the above photo, before launching and flapping away with large wing-beats, his PTT aerial waving in the wind. As I had suspected earlier this year, Wallu and Wurru had constructed a new nest, which I spied close to Wallu's perch tree, built 10 m up in another Cue York Gum.

Well hidden among the foliage of a Cue York Gum, Wallu and Wurru's new nest is only the fourth of over 90 wedge-tail nests built in this tree species at the Matuwa/Lorna Glen study site.

My prediction was that Wallu's regular visits to the nest site recorded by our tracking data over the past 2 months indicated that a chick had hatched and continued to be fed on a daily basis. It was most exciting to discover that this also proved to be true, and a split second after spying the nest, I noticed an eaglet standing on it, looking large and healthy. Climbing the nest, however, gave me an even better surprise: not one, but TWO large, healthy eagle chicks!

Two large female eaglets, aged about 8 weeks old.

As part of my research on the movements of juvenile eagles from Matuwa, individuals are being ringed with blue leg-rings (you can read about the first year of conducting such research in 2014 here). The 'twins' from Wallu's nest were lowered to the ground in a handling bag, then removed and held for processing. Even at this age, eaglets have powerful talons which can inflict severe wounds to a human, so care is always taken to hold the birds firmly but gently, ensuring no injuries are sustained to them or the handler.

Removing one of the juvenile eagles from the handling bag - feet first!

       

                                                                                                                      Taking measurements from the eaglets: the tarsal length (left), and rear talon (right).

After data on their morphometrics such as weight, wing length, tarsal (lower leg) length and size of the rear talon were taken, two leg rings (a blue, numbered colour-ring, and a stainless steel ring from the Australian Bird and Bat Banding Scheme) were fitted to the birds' tarsi (all ringing is conducted under appropriate licenses from State and Federal Government authorities). The blue colour rings are unique to this study site, so we know that any eagles bearing a ring of this colour that are subsequently sighted elsewhere in Australia originated from Matuwa/Lorna Glen. As we've seen from Kuyurnpa's amazing travels, eagles can move thousands of kilometres in their first year, so no matter where you are in Australia, keep your eyes peeled!

      

Holding an eaglet firmly by the tarsi and tucking up the wings prevents it from causing any injuries to itself or the researcher (left). The blue colour-rings have a unique number which identify the individual birds (click images to enlarge).

It was encouraging to record both juvenile eagles were large females, each weighing over 3 kg! And at eight-weeks of age, they still have some mass to put on, so will probably have fledging weights much greater than their father Wallu (male eagles are smaller than females, weighing about 3 kg at the most, with females occasionally exceeding 5 kg).

When the processing was complete, the 'twins' were returned to the shady canopy and replaced on their nest.

These juvenile eagles are the first record of a brood of two surviving to near-fledging age in four years of research on more than 30 resident breeding wedgie pairs at this study site. Due to an overall low food supply, most pairs rear 0 young per year, and a maximum of 5 pairs have reared 1 young each in previous years. Such findings are typical for long-lived raptors and are consistent with previous research on this Australian eagle species in arid parts of its range, where rainfall is erratic. Perhaps having satellite tracking devices on eagles increases their breeding success!?! ;-) Well done Wallu, on a fantastically successful breeding season in 2015!

Tracking Well

We didn't have much to report on our two satellite-tagged wedgies Wallu and Kuyurnpa during most of September - both stuck to a fairly similar pattern in their behaviour as previously recorded, with Wallu still tending his (apparently) successful nest site regularly, and Kuyurnpa drifting back up to Roy Hill again and spending most of the month there. Towards the end of the month though, our girl appeared to get itchy talons again and on 20th September embarked on a 1300km desert wander which saw her pass over the Matuwa homestead and continue further south-west than she has ever previously ventured! Today's latest waypoints show Kuyurnpa has again revisited the familiar ground on the north-western side of Lake Carnegie. This journey is shown on the above map (click to enlarge).

Here is a map of Wallu's past month of regular visits to the nest site (large cluster of red dots centre right), and the nearby rabbit warren (smaller cluster to the south-west of the nest). This week I will be heading to Lorna Glen to carry out more research on the breeding and diet of this eagle population during 2015, which will include a check on Wallu's nest. Watch this space for a few more regular updates!

Fly-past

Kuyurnpa remains in close proximity to her birthplace! A month ago she completed a 230 km 'home run' across her natal territory, starting and finishing at a roost site located about 40 km north-east of Matuwa. Not long after that, the young eagle headed west again, spending three nights at the edge of a large claypan, as shown by the green cluster of GPS fixes in the above map. The 15th July saw her cross her natal nest site again, and this time continue further east. Kuyurnpa has spent the two weeks since that date skirting Lake Carnegie, a giant inland claypan situated in the middle of the West Australian desert.

During the latest journey east, Kuyurnpa travelled very close to our resident adult male Wallu. GPS fixes from 15th July at 3 pm show these two eagles were only 15 km apart - but both birds have different priorities in life right now. While Kuyurnpa is still very much in her juvenile wandering phase, traversing the country widely on her own, Wallu is seemingly very busy providing food to his mate Wurru (and perhaps a new chick) at a new nest site in the woodland area. Will we find later this year the first successful hatching of a Wallu eaglet since satellite tagging?  I can't wait to find out!

A New Nest?

As the eagle breeding season approaches, I've been tracking the daily movements of our male wedgie Wallu, and paying particular attention to where he has roosted each night. In the last 2 weeks he has spent more than half of his nights at a particular tall gum-tree in a small patch of woodland about 700 m north-east of his favourite rabbit warren hunting place. This is shown by the cluster of GPS fixes in the above picture (click to enlarge). I have inspected this site a few times in the past year and discovered the perch tree is a tall Cue York Gum (Eucalyptus striaticalyx) with quite a few nice horizontal perches, perfect for eagles to land on. When not roosting at the actual tree, Wallu has still remained close by, spending every night within a 1 km radius of it. It has been interesting to observe a shift in his behaviour - over the summer period he often roosts in tall Gidgee trees on the high ridge that forms the northern border of his territory, close to his two existing nest sites, and only visits the Rabbit Ridge every few days.

The fact Wallu has spent an increasing amount of time in this area as Wedge-tailed Eagles are preparing to breed makes me think him and Wurru have built a new nest here. When I learned how often he visits the nearby rabbit warren, I did wonder why this pair persisted at attempting to breed (and subsequently failing) in nests which were so far from their apparent key source of food. It would make sense to build at a site much closer to an abundant and readily portable supply of prey. I am very much looking forward to visiting the territory later this year to see if my prediction is right!

Home Run

Kuyurnpa has continued her urge to return home! After her recent long journey south, she stopped to rest for a few days 70 km north-east of her natal territory (scroll down to read more). In the next 2 days the satellite tracking data showed her head south-west from here and, around 2 pm on 2nd July, pass right above the nest on which she hatched nearly 2 years ago. Kuyurnpa then flew directly south and roosted not far from the site where she spent her first ever night alone (on 29th March 2014), clocking up 115 km for that day. By dusk tonight (3rd July 2015), she was back at the northern roost site again, completing a 2 day, 230 km 'home run' loop. Does this behaviour indicate she is wanting to return home, or is searching for a vacant breeding territory near where she was born? I still feel it is a little early for Kuyurnpa to breed, and although we know from the CSIRO's work in the 1970's that most breeding eagles are adults aged more than 6 years, we have no data on when Wedge-tailed Eagles might begin their settlement. We will only gather some insight by continuing to track Where Eagles Dare - and you can assist with that by pledging your support to help this eagle tracking project continue. Visit the Crowdfunding Campaign for information on how you can help!

230 Clicks South

Kuyurnpa has in the last week been on the wing again, clocking up more remarkable kilometres during a sudden journey southward. Our young eagle, who is approaching her 2nd birthday next month, added 460 km to her odometer in a 4-day flight that saw her leave Roy Hill and fly back towards home soil. On one of these days, Kuyurnpa moved an amazing 230 km between 10 am and 4 pm, with one GPS fix recording her travelling at just over 90 km per hour! Just when I thought she might settle in the Pilbara region for a while (Kuyu has just spent 6 consecutive months on an area of Roy Hill that is approximately 100 km wide), this wandering wedgie has zipped across to the Gascoyne region, stopping about 70 km north-east of her natal territory. This is the closest she's been to her 'home' since roosting 60 km away from it on 27th October last year. Will she stay here longer, or will she continue to move on? The only way to know is to check in again soon!

Don't forget to view the video to the Crowdfunding Campaign I launched just over 2 weeks ago, where you can pledge your support to help this eagle tracking project continue.

Kuyurnpa's journey south south-east, showing 4 days travel.