Welcome to the News section of the iNSiGHT Ornithology website (
www.simoncherriman.com). This blog contains updates about various things I've been up to, interesting environmental issues and observations I make regularly while going about my day. It is designed to be fun AND educational, and inspire you about our wonderful natural world. Happy reading!

Friday, 29 September 2017

Darlyininy


In the Noongar language, the word 'Darlininy' means 'to go swiftly' ('iny' at the end of a Noongar word is the equivalent to the English suffix 'ing', but it is pronounced with a 'y' as in onion: 'in-ye'). Why is this relevant to eagles? Today, while extracting from a handling bag the young eagle who owns the fearsome-looking feet pictured above, I somehow managed to misjudge an attempted grab at one of his legs, then felt a sharp pain as a foot grabbed my hand sideways and a well-aimed talon punctured my palm (don't worry, it was just a flesh wound!). This happened in the blink of an eye, and I thought "Wow, that eagle moved swiftly!". This stuck in my brain until tonight, when I was considering a suitable Noongar word to use for the first juvenile Wailitj / Wedge-tailed Eagle to be fitted with a GPS/Satellite Tranmitter for the 2017 season. The name stuck. So where was this being carried out?

Juvenile eagles are removed from their nest and lowered to the ground in a canvas bag.

Whiteman Park, a recreation and conservation reserve located 18 km north of the Perth CBD, is fortunate enough to have two breeding pairs of wild Wedge-tailed Eagles residing in bushland. I have monitored with interest the breeding behaviour and diet in one home range since the first year of my university Honours project in 2004, recording 17 juveniles fledgling in 12 years. A second pair established a breeding home range quite recently (in 2015), the result of a particularly high density of Yonga / Western Grey Kangaroos living in this area (lots of eagle food). I refer to them as the Cullacabardee pair, named after the Noongar word and nearby suburb.

In June 2016, Whiteman Park staff found an adult female Wedge-tail dead beneath powerlines, nearly 5 km from the 'nest centre' of the Whiteman pair. The discussion below a post by the Western Australian Birds of Prey Centre regarding this death contains many assumptions about individual eagle identity, pair composition and breeding chronology which paint an inaccurate picture of what was actually happening in the wild. The dead bird may well have been a female from one of the resident pairs, but we have no way of identifying individual birds without marking them with leg bands or wing tags, and there was no such proof of 'who' this bird was. It may have been a local resident, or quite possibly a 'floating' (i.e. unattached) adult female from elsewhere. While the Cullacabardee pair was present constructing a new nest, I recorded no breeding activity in any known nests belonging to the 'original' Whiteman pair, nor did I locate a new nest, but did make several observations of an adult male eagle perched alone. This meant two things: 1) 'his' female had indeed died just prior to breeding (albeit a long way from 'home') and he was alone in his breeding home range, or 2) an adult female was still present, was attending a new nest that had escaped my detection during nest surveys, and the male was seen alone while the female was busy with 'mothering duties'.

It late 2016, I was carrying out some tree-climbing work for the Park when I flushed 2 juvenile Wedge-tails from the ground about 2 km from the Whiteman pair's existing nest sites. These birds were also captured on motion-sensing cameras nearby in subsequent weeks, confirmation there was definitely a successful breeding event in this home range and the death of an unknown female had not impacted productivity in the Whiteman home range. I now knew for sure that there was a 'missing' nest, so I set out in the 2017 breeding season determined to find it.

One August afternoon I located the Whiteman pair circling high above the Banksia woodland, then watched them simultaneously plummet from the sky to disappear below the tree-line. I followed my compass to a small 'valley' in between two sand dunes and suddenly came upon the nest, built very low in a dead Marri. This nest was atypical in that it was small, low down and not visible using traditional searching methods of scanning trees from a distance, proof that even massive raptors can be hard to find! I scaled this tree and was delighted with the scene in front of me!

The second egg in this clutch failed to hatch: it was infertile.

The news of this successful hatching in their conservation area, and the preparation of a new nest by the Cullacabardee Wedge-tails, prompted the wonderful Whiteman Park staff to agree to sponsor two transmitters for my PhD research. As well as helping me answer questions about juvenile dispersal, this would allow more detailed information about the Whiteman eagles' use of various habitats at the Park to be gathered.

Six weeks after locating the nest, this tiny eaglet had transformed into a well-feathered juvenile eagle. At first glance the nest appeared empty, but soon after sorting my camera I was met with the glorious sight of the eaglet standing up and lifting his new wings into the westerly wind! It was wonderful to see him doing so well and approaching a size suitable for satellite-tagging.

An 8 week-old Darlininy stretches his new wings.

When he had reached the age of 10 weeks, I was joined by Perth bird-banding mentors and good friends Mike and Mandy Bamford (whose wonderful enthusiasm for banding allowed me to begin colour-banding Perth wedgies in 2015), Sarah Stevenson from Whiteman Park and a few university students to visit the nest and fit a transmitter to Darlyininy. He was smoothly captured on his nest, lowered to the ground in a handling bag and (after his initial aggression at my palm!) held calmly in place while I adjusted his harness and began to stitch the Teflon.

Wailitj birds have a strong Aboriginal background!

Haemostats hold the Teflon in place in preparation for stitching the week-link harness.

The above image shows how a cardboard template is used to position all four straps of the transmitter harness evenly across the eagle's breast-bone. Once adjusted, the Teflon straps are crimped in place with haemostats, then a single 'weak link' is stitched through all four pieces where they meet in the centre. I am most grateful to Ewan and Jenny Weston from the Scottish Raptor Study Group, with whom I have been privileged to spend time learning raptor ringing and tagging techniques in Scotland, for teaching me this method.

It was fantastic to finally band an eagle with Mike and Mandy.

With metal and colour-rings/bands and a GPS/Satellite tag fitted, it was time to return Darlyininy to his nest. He posed for a quick image of his amazingly beautiful set of new wing feathers before being placed back in the handling bag and hoisted back up the tree.

Juvenile eagles' have conspicuously banded primary and secondary feathers.

Darlyininy assumes the threat posture typical of nestling wedgies.

It was wonderful to see Darlyininy back on his eyrie with a transmitter safely attached, and know we will be able to follow his first movements when he takes to the sky! For more information on satellite-tagging and to follow this and other eagles' progress, check out the Wedge-tailed Eagle Tracking website here.

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