Invaders?

This morning I collected a motion-sensing camera which I had set up on the kangaroo carcass we used to catch Wallu just over a week ago. The 'roo had now been dragged out of the trap and the trap closed, to ensure we didn't catch any other eagles. Setting the camera up had indeed paid off - it gave us the first close glimpse at Wallu with his transmitter we've had since we released him!

This video shows Wallu's mate Wurru feeding at the carcass, then looking up and calling softly as he dropped down from the perch to join her, offering the camera a good glimpse of his PTT (shown circled in the picture above). You can see he's still very wary - the last time he fed on this carcass he was caught by some researchers!

Then something really interesting happens. Wurru is disturbed by something, looking skyward and running out of shot before taking off. Wallu soon follows, and only minutes later, a THIRD eagle lands to investigate the carcass! This one is a sub-adult male. You can see this from his much paler nape (neck feathers) and more golden wing-bar that he is a younger bird, and his sex is revealed by his relative size (smaller than the female), and shorter head and bill. There is also a Willie Wagtail in shot - but somehow I don't think he is the reason the eagles flew away :-D




Eagles Caught on Camera from Simon Cherriman on Vimeo.

Is this bird an invader? Why does his presence disturb Wallu and his mate so much? Maybe they left instantly to defend their territory. And maybe Wallu's relationship is being tested by the presence of a younger, more hansom male! We will find out further into the breeding season if Wallu remains in his territory and fathers offspring. More updates soon!

Tracking them Down

The excitement out bush continued today when we spotted an eagle perched in a dead tree not far from Trap 2, the location at which Wallu was trapped last week. A closer look at the bird revealed it was a large female – Wallu’s mate Wurru! I knew he couldn’t be far away, and minutes later I saw him perched in a live gidgee tree on an adjacent hill. He flew as soon as I left the vehicle, as did the female, but we noticed both birds settled in another dead perch tree a few hundred metres off the road. Although the odds were it was Wallu, I needed to sight his PTT (transmitter) to confirm. Neil and I stalked them, keeping hidden behind a small ridge, and managed to get within about 100m.

I set up my long zoom-lens and framed both birds – Wurru facing sideways, the male facing us front on. Where was the PTT!? I couldn’t see his back! As though hearing my thoughts, he suddenly turned around and revealed his back… and I saw it! The PTT sat perfectly, aerial probing skywards. He was alive and well!

Wallu's PTT is visible as he turns to fly from the perch tree.

A sighting of Gidjee earlier that morning revealed she was also doing fine, flying low over the pen not far from her release site. We now had a couple of records of our eagles since their release, making us confident they’ve resumed their normal lives. Tracking information from the PTTs also confirmed this, and for the first time we have been able to view the birds’ movements and ‘see’ what they got up to after we released them. Here’s a map of Wallu’s story…

 

You can see from this amazing imagery (thanks to Google Earth!), Wallu roosted on a hill about 1km from the trap site (green circle). First thing the next morning, he flew straight to an area bordering the lake system and spent a few hours there (blue circle). (Later inspection revealed this site was a rabbit hotspot, littered with piles of dung, diggings and a few large warrens. It wasn’t surprising – the day after trapping, Wallu was hungry, and flew nearly 4 kilometres to exactly where he knew he could get a meal). He then returned to the ridge to the north of the trap site and spent some time at one of his nest sites, roosting that night close by. The next day was spent close to this nest site, possibly because he was helping Wurru gather lining for it in preparation for the upcoming breeding season. Yesterday at mid-morning, Wallu again made a beeline to Rabbit Ridge, probably for another feed, before flying to perch near the road where we sighted him

'Rabbit Ridge', showing one of the perch trees Wallu has been using on the right.

The map from Gidjee’s territory also reveals her movements, shown in close proximity to the fenced enclosure (blue line) containing many reintroduced native mammals… 

We know Gidjee roosted not far from the trap the night of her capture (shown by the red circle just above 'Trap 1' in the above map). The next day she spent the morning on the ridge overlooking the enclosure, before perching in a tall patch of eucalypts on the plains below (yellow circle). Roosting nearby that night, she began her Monday morning with a flight above the nearby ridge, then spent the afternoon perching in patches of tall eucalypts, both in the enclosure (near an active Boodie warren), and then another patch further south of the enclosure. This behaviour may well be associated with investigating possible prey areas: these eucalypt areas are productive, usually supporting good numbers of rabbits, kangaroos and birds.

Later on we visited the area of tall eucalypts inside the pen and discovered Gidjee and her mate Mulga had built a new nest here! This is probably in response to an increase in prey density inside the fenced enclosure, as the native marsupials thrive in the absence of feral cats and wild dogs. More light will be shed on Gidjee and Mulga's breeding in this new nest as the year progresses.

Where Do Eagles Dare?

AND AGAIN!!! Today marks another day of incredible excitement in our eagle capture mission. During mid afternoon, another adult eagle from a neighbouring territory near that of the male we trapped last night was seen perching on one of our crow traps. We waited an hour then approached the trap in gripping suspense. At first glimpse there were no birds to be seen, but a few seconds later we saw two eagles take off from the ground near the trap. They were both outside, peering in at the bait. We aborted again and drove to a nearby wetland area to kill time. The sun was disappearing and light was fading fast. I began to hope that the eagles had left the trap alone - it would be much better to catch one fresh in the morning, rather than last thing at night.

Just after sunset we approached the trap for the third time. I was as nervous as ever. Nothing moved in the spotlights as we slowly drove up. Neil and I got out of the car and walked slowly to the trap. I saw a small glint. Eyeshine. Then a large shape moved - another eagle was trapped! We burst into action and raced to the cage, with nets ready to secure the bird. This one, a very large adult female (and JUST the bird we had on our target list!) was much easier and within minutes she was caught, blinded and calm. (You can tell she is a female by her much larger head and enormous talons, visible in the above photograph).

After processing and securing the second transmitter (known as a PTT - Platform Transmitter Terminal), the bird was ready to be released. With massive wing-beats and a crop full of kangaroo and feral cat (both carcasses used as bait), she flew into the night and landed in a low bush. It was a bit of a worry to leave her in this position overnight, but interfering now would do her no good. We wouldn't be able to re-capture her without a lot of effort and a risk of causing her an injury. And we instantly ruled out the thought of holding her over night due to the amount of stress this would cause her. Besides, eagles had often been recorded roosting on the ground in treeless plains. Who would dare mess with our largest avian predator!?

In morning darkness Gill and I set out again to attempt to locate the bird at sunrise. A heavy fog prevented us from seeing more than 50 metres but when the sun had burned most of it off at around 10am, I caught a glimpse of a shape perched in a tree on the nearby ridge. It was the female, and through binoculars we sighted her preening her new backpack. She was alive and well!

EAGLE MOVEMENTS

I'm REALLY EXCITED to give you a preliminary look at the first set of location data from our GPS PTTs, which reveals some fantastic information. Below are two maps showing the movements of each eagle several hours after release. The first maps our male, who will now be dubbed Wallu (a variation of the traditional Martu name for Wedge-tailed Eagle, 'Wallu-wurru'). After release from outside crow trap number two, Wallu flew about a kilometre to roost in a tree on top of a ridge, not far from several of the nests in his territory (the nests are not shown). From this point he also has a great view over the lake system to the south, visible on the map. The lake is currently dry but in good seasons attracts hundreds of waterbirds.

Looking at the second map, we can see the very first movements of our female eagle, who I will now announce is named Gidjee (named after a local tree in which eagles most commonly build their nests). Although we arrived at her release site before sunrise today, we did not sight her until mid morning, and the satellite information was not available until later this evening. This meant our only means of detection was to sight her in the flesh. By the time we had walked up the ridge on which she was perched, both her and her mate (who had been hanging around the trap area all morning and eying off the dead kangaroo which we removed from inside the trap!), flew away to the north-west. Some quick detective work revealed the tree she was perched in, which had several fresh scats beneath and a few feathers. We recorded this perch tree with a handheld GPS, and were thrilled to later find it matched perfectly with the location shown below, as recorded by Gidjee's harness-mounted PTT.

While this data is only the tip of the iceberg, it bodes well for a great future of further records. It is incredibly exciting to reveal that this is the FIRST TIME EVER adult Wedge-tailed Eagles are being tracked by satellite!! Never before has anyone been able to look at a map and view the location of our largest bird of prey from a remote location. If you are reading this, I thank you for sharing this exciting time with me! Please keep your eyes on this blog for more updates on Wallu and Gidjee's progress, and for news of the documentary film which will be released in the near future.

When you next glance skyward at an eagle, just think if you have ever before wondered: "Where Do Eagles Dare?"

The Eagle Has Landed!

It's not every day you get to make a boyhood dream reality!!! After arriving at Lorna Glen for our eagle capture mission on Tuesday, I was absolutely ecstatic today when we were successful in capturing an adult Wedge-tailed Eagle (this one a male) after less than 24 hours of trapping. Fitted with a long-term solar GPS/Satellite transmitter, this bird will allow us to track its movements over the coming years. Today is a day I will never forget - suspense, excitement, nervousness, and capped with raw emotion and happiness. I must start by saying a huge thankyou to all my wonderful support crew - Gill behind the camera and at my side as always, Neil H the extraordinarily calm and wise eagle handler, my close friend Judy who first introduced me to this study area, Mum and Dad here with me in spirit in everything I do, my Aunty who left us so suddenly last week and is now looking down on us all, everyone who has helped in the preparation.... and most importantly, these majestic, MAGIC eagles which continue to bring me inspiration, as they have done for much of my lifetime. Here's how the day went...

We baited the 'crow traps' (a large wire cage) yesterday arvo with a few road-killed kangaroos, and on our way out to prepare another trap site after lunch today, we saw an eagle circling near one. We slowed down to get a closer look and our binoculars confirmed this was a dark adult bird. Just what we wanted. This pair was not the primary target but (I think) the neighbouring pair towards the east. A little further down the road and we found a second adult bird perched in a tree. (This was almost certainly the mate of the bird just seen, and also very dark). We carried on to continue with our trap setup and worked for about an hour, when a call on the radio excited us. It was Judy saying that she'd just driven past an adult eagle perched right above one of our baited traps! Knowing how alert and suspicious adult eagles are, I just didn't believe they would go into a crow trap... but we held our hopes. To be honest I wasn't feeling the best and didn't feel like catching an eagle - I wanted my headache to have cleared before the big moment. But it is often at the strangest of times when these rare moments descend upon us.

Half an hour later we left our tools and drove down the road towards the the trap where the eagle had been sighted. My nerves rushed as we slowed down for the last 50 metres, then stopped. I glanced out the window. BOTH BIRDS were at it - the male inside the cage and the female sitting on the ground outside. She launched into the air and flew as Neil and I dashed to the trap. I expected the male bird to try and fly out - he didn't. He  just stayed on the ground and tried running into the wire. I wanted to pin him urgently and Neil hadn't yet got the gate open, so I just dived over the fence and secured the bird with my net. Soon Neil was in and also placed his net over the eagle, then grabbed his legs. Even before we had it caught, I was amazed at how calm this bird seemed. The eagle had hardly flapped and only jumped at the side of the cage a couple of times. When secured it was totally uninjured - not a scratch. And it became even calmer when I had it blinded (thanks a million to Nick Stanton for making me such a perfect fitting falconry hood!).

The rest they say is history (although you can watch the whole thing when my documentary comes out!), but it took about 40 minutes to fit the transmitter, then band, weigh and measure the eagle, before it could be set free. Just before sunset we released him, and had tears welling in our eyes as he flew away down the road beautifully, not a feather out of place, with the transmitter firmly on his back, flapping his huge wings and lifting himself above the mulga scrub. A dream come true. But only the first phase complete. We still have one more bird to catch...