Friday, 17 October 2014

Cute Chicks

Wedge-tailed Eagles are now well into their breeding season at Lorna Glen, and over the last few days we have been checking nests for breeding success. So far five nests have had large chicks! The one pictured above is the same chick shown at the start of the previous blog post, just 6 weeks later - isn't the change incredible!? To gather data on their dispersal I am ringing/banding the eaglets with coloured and numbered leg rings. This will hopefully make them recognisable in the field when the eaglets fledge and leave their natal territory, and give us information on where these young birds disperse. 

Kuyurnpa is an eagle chick that was fitted with a satellite tracker in 2013, and while ringing cannot provide as much detail as satellite tracking, it does at least create an opportunity for a re-sighting at some stage in the future.

Lowering down an eaglet from a particularly small Wedge-tailed Eagle nest. Don't worry - I'm harnessed in!

To fit the rings, eagle chicks are removed from their nests and lowered to the ground in a closed bag. They are then placed gently on a folded sheet where they sit quite happily as they are processed. I followed the same methods used by Golden Eagle researchers Ewan Weston, Rab Rae and Stuart Rae in Scotland, whom I accompanied on several ringing forays in the highlands earlier this year. This method allow for efficient processing and minimal impact to the birds.

Neil Hamilton holds an eagle chick as I attach the leg rings.

Once on the ground, the first step is to fit the rings to the eaglets' legs. An Australian Bird and Bat Banding Scheme (ABBBS) band is fitted to the right leg, then a unique colour band (right) is placed on the left leg. Bands do not harm the bird in any way - they have been designed to fit the leg comfortably: loose enough so they don't cause damage, but tight enough so they don't come off or get caught on vegetation. Furthermore, all banding conducted at Lorna Glen is licensed under the West Australian Wildlife Conservation Act and has been approved by an Animal Ethics Committee. The colour bands I am using are also the same design as those being used by my friends in Scotland. I am hoping they will be visible enough to be seen by any keen bird-watchers or photographers who can report sightings to me once these eaglets take to the air and leave home!

After the ringing is done, several measurements are taken from the bird, including weight, head length, wing, leg and talon length - these can be used to age and sex the eagle at a later date.

An eaglet aged ~7 weeks sits calmly as it is fitted with an ABBBS band.

The head-bill measurement is taken after fitting both leg bands (you can see the blue colour band on the eaglet's left leg.

When the banding and measuring are complete (the whole process takes about half an hour), the eaglet is placed back in the handling bag and hoisted back up to its eyrie. Here it sits and waits for its parents to return to the nest, hopefully with food. The adults have more than likely been watching the whole process from somewhere up high, but our presence at the nest does not significantly alter their behaviour. At this stage of the nesting period it is common for the parents to spend most of the day off the nest and away hunting. Their chick sits on the nest, keeping to the shade when it can, and watches over the surrounding Mulga shrubland, honing its skills at spying moving objects, and occasionally standing for a practice at wing-flapping.

Removing an eaglet from the handling bag to return it to its nest.

Several days after ringing each wedge-tail chick, I returned to check up on their progress, to ensure their parents had returned with food since the disturbance, and to check the rings were still in the right place. All were doing well. This one, the smallest (probably male) eaglet, was sitting up waiting to greet me as I poked my head over the edge of his eyrie.

Below you can see an ~8-week old eaglet with its new rings. This was the oldest chick we banded and it had quite large wings and very well-developed body feathers compared to the others. It should be easily recognisable with the blue colour band '005'. Where in WA will this young wedge-tail turn up next?

Thanks to Neil Hamilton, my 'eagle handling mentor', for overseeing the process of eaglet ringing. I would also like to thank John Angus, Pam Cherriman, Gill Basnett, Mark Jeans, Ayla Wilson, Bruce and Kaye Withnell and Tammy Elliott and her family for their assistance during the past few weeks.

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