Saturday, 15 June 2013

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?"

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