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!
Tuesday, 13 June 2017
You might remember a few weeks ago when I was thrilled to find Kala, our sat-tagged juvenile Wailitj hanging out with his parents, and be lucky enough to take some close-up photos of him perched in the morning sun. Today Australian Geographic reported on a recently published journal article about Wedge-tailed Eagle movement ecology (as studied by DNA), and one of these photos of Kala featured as the headline image! You can read the article, which contains some very interesting findings about the ecology of wedgies in Tasmania, at the Aus Geo blog here.
Friday, 2 June 2017
Early last year the City of Armadale gave me the wonderful opportunity of installing a variety of nest-boxes for wildlife throughout several bushland reserves, many of which were designed for Black Cockatoos. I was extremely excited when Tony Kirkby, a cockatoo biologist, who, along with Ron Johnstone from the WA Museum's Cockatoo Care Project, has studied Kaarak's (Forest Red-tailed Black Cockatoos Calyptorhynchus banksii naso) for many years, emailed me through the above photo. This was a fantastic sign that less than a year after installation, one box was being used for breeding!
|Fresh chew-marks on the sacrificial chew-posts provide convincing evidence of cockatoo occupancy.|
Today I was installing more nest-boxes (this time for microbats) in the area and took the opportunity to visit the active cocky box. Under Tony's guidance on the phone, I walked quietly through the bushland to the nest tree, and after observing for a few minutes then 'raking' (knocking on) the nest tree, discovered the female did not emerge. This was a good sign that a chick had hatched because adult Kaaraks are known to only brood their nestling for a week or so, then leave it on its own for most of the day while away foraging. Tony was happy for me to scale the tree and confirm there was a chick present, and also to photograph in order for its age to be estimated. When I reached the rim of the nest-box, I was met with this absolutely remarkable view!
A tiny ball of yellow natal down-feathers huddled in one corner of the nest-box, swaying ever so gently from side to side. This beautiful new gift to the world was only the second Kaarak chick I had seen in real life, and appeared a lot smaller than I expected. I lowered my camera inside the box to snap a few closer photos from a side angle, then film a few short video clips (watch a short one of this beautiful young bird on my Facebook feed here), just as a large flock of Baudin's Cockatoos flew noisily over the treetops. The nestling made a few soft rasping noises and swayed from side to side, but otherwise showed no reaction to the goings on in the outside world. Keen to keep disturbance to a minimum, I snapped some descending gear onto my rope and left the canopy behind, then walked away from the nest tree as quietly as I had come. The only sign of adult red-tails was a single, distant 'kreeee'.
After seeing these photos, Ron and Tony tell me this young Kaarak is just under a week old, and is quite young to be left alone by itself, but it does happen. I am most grateful to Tony and Ron, who mentored me during the successful use by Carnaby's Cockatoo of a nest-box in the Mundaring Shire just over a year ago, and who continue to offer guidance with various ornithological projects I am involved in. What a lucky find - and an awesome way to end the week!
Monday, 29 May 2017
Interactions between Wedge-tailed Eagles and drones are becoming more frequent as humans intensify our land use and make increasing use of aerial vehicles for survey work. In the last few weeks, many people have sent me a link to this ABC News article which featured the above image, taken by Leigh Nairn while using a drone to taking photos of his farming activities, of an eagle just before it attacked the camera. Today I received a timely call from the ABC who were keen for my opinion about possible impacts of such attacks to the eagles, which came just as I was driving to the vet with the carcass of Walyunga, a Perth-born Wedge-tail that flew to the Pilbara region less than a month after beginning juvenile dispersal. Walyunga died suddenly and the evidence suggests this was because his wing feathers were chopped by a small, fast-spinning rotor-blade, like that on many drones (i.e. those larger and with more blades than the typical commercial example of a DJI Phantom or similar, which is what most people imagine when they think of a drone). As I mentioned to the ABC, it's not only drone operators who suffer losses as a result of these interactions, and it places emphasis on the importance of research that may potentially determine ways to minimise their occurrence. Part of my PhD research aims to investigate 3-dimensional space use of territorial adult eagles, but a big gap at this moment is funding. I'm applying for grants but am always keen to hear from anyone that may wish to sponsor my research. If this is you, please email me!
You can read more about tracking eagles using GPS/Satellite technology at the Wedge-tailed Eagle Tracking website here, and also listen to the interview on the ABC's Country Hour website here (the segment on eagles and drones starts at 32 minutes). Let's hope we are able to combine eagle tracking and drone operations to help find a solution to this human / wildlife conflict.
Thursday, 20 April 2017
While out in Wailitj (Wedge-tailed Eagle) Kala's home range today, I came across this dead Yonga (Western Grey Kangaroo), a common prey item for eagles during this time of year. Closer inspection reveal some fresh scats (the white blotch in the bottom left of the photo), and footprints in the sandy gravel told me eagles had fed on the carcass very recently. Suddenly, some crumbling bark falling from above made me look up, and THERE, peering down at me with gimlet eyes, was Kala! The hairs on the back of my neck stood up, and I rush to get my camera, but the eagle launched and flew to another tree and I only managed a fleeting snap as he let out a begging call to his mother, who was perched on the other side of the river, and disappeared behind the trees. The next morning, however, I woke up in the dark and headed back to see if I could catch the family back at the 'roo at first light, and sure enough, Kala's golden juvenile feathers were the first thing I saw glowing in the rising sun's rays.
|Kala's PTT aerial and yellow colour-ring are clearly visible in the morning sunlight.|
|These beautiful blonde wing covert feathers provide a great example of the wide dorsal wing-bar typical of juvenile wedgies.|
Juvenile eagles like Kala have in their first year a very golden or even blonde appearance. While their breast and belly is often dark brown with pale flecks, the crown, nape (back of the neck), mantle ('shoulders'), and the 2 main layers of wing coverts (median and lesser primary and secondary coverts) are very pale in colour. As the bird ages, its overall appearance becomes brown after 3-4 years, then black after 6-7 years. The 4-5 rows of very pale covert feathers on the dorsal surface of the wing, as seen clearly in the above photograph, are a key feature which allows the bird's age (within a year or two) to be determined, thanks to the detailed observations of Michaels Ridpath and Brooker, who published this information in the 1980's. Despite looking at eagles for so many years, I have not been able to take a photograph of a wild bird which shows this detail so clearly.
What was also very interesting was to notice how Kala's pale feathers had become much lighter in colour since fledging. When I watched him take his first flight from the nest nearly 5 months ago, his juvenile feathers had quite a reddish-brown appearance. Check the last photograph on this news post to see the amazing change!
After walking right beneath Kala, who this time seemed much more accepting of my presence, I spotted his parents perched in a dead tree on the side of the rugged valley slope. Sneaking closer, I was thrilled to be able to photograph both birds together before they slunk away.
|Kala's parents, a classic pair of dark, adult Wedge-tailed Eagles. The male is on the right.|
The first thing I noticed about this pair was how dark the female (on the left in the above photo) had become since I last saw her 5 months prior. Here's a closer image of this magnificent bird, which shows her overall black appearance, with evidence of some pale nape feathers and a few 'blonde' covert feathers on her wings.
|The pale 'lump' in this eagle's throat is her bulging crop, half full of the kangaroo on which she had fed earlier.|
When Kala was still a nestling, I managed to photograph the same pair perched near their eyrie, and back then the female had a much paler nape and her wing. This suggests she has undergone a significant moult since her chick fledged at the end of 2016.
Winding back the clock a little further, the same female was even paler in 2015 when I first noticed her as a particularly young bird and a 'new addition' to the territory. After successfully breeding in 2013 (when I managed to capture quite a bit of footage of this pair's nesting behaviour), the resident (very dark and mature) female had gone missing, and I'd seen the male on his own on a couple of occasions. Then I spotted him with a very pale bird, at first thinking this could be his offspring from the previous breeding season. I soon realised it was his new mate, however, when I observed him 'showing her the real estate' by performing exhilarating dives from above the valley and landing on several eyries. She followed him closely and the pair perched together in several nest trees, keeping a close eye on me while scanning the valley below. On that day I didn't have a zoom lens with me, but did manage to capture a few distance photographs (in very low light!) that show how pale the female was in August 2015.
|Kala's mother was very pale in August 2015 when she first paired up with the resident male.|
|The new female's nape was very pale in 2015 when I estimated her to be ~3 years old.|
Although Wedge-tailed Eagles do not normally enter the breeding population while immature, there are certainly records of birds breeding before reaching the normal 6-7 years of age, when they can be more or less considered 'full adults'. Kala's mother was certainly in immature plumage when she joined the resident male in this home range, and it has been amazing to see her darken over the past 3 years and attain her stunning adult appearance now.
When Kala's parents met in 2015, the pair only inspected and refurbished nests and did not attempt to lay eggs until 2016. This behaviour is quite typical of long-lived birds that do not necessarily breed every year anyway, and it has been very exciting to have a bird that is recognisable and allowed me to follow the pair's progress. The changeover in females provides good evidence that when existing birds die or leave a breeding home range, they can be replaced quite quickly and the home range can continue to be productive. Knowing that we will be able to follow with satellite tracking the movements of Kala, the beautiful eagle that is (almost certainly) his mother's very first offspring, is indeed an exciting feeling!
My last view of this eagle family was seeing Kala swoop in to join his parents on a tall, dead perch tree, and begin to preen his feathers. With this magic sight in my mind, I glanced at my phone to check the time. 8 am. Perfect time to start my day!
You can see more images of these and other beautiful eagles, and a short video from this exciting find, on my Instagram account here. Happy eagling folks!
Saturday, 15 April 2017
It's never pleasant to find dead animals killed by vehicle collisions along our roads, but taking the time to investigate a carcass can lead to important scientific data being gathered. Peter Jephcott, who was recently crossing the Nullarbor, had stopped to take a closer look at a dead Wedge-tailed Eagle when he noticed it had a yellow ring/band on its left leg. He then took the time to locate the second stainless-steel ring on the bird's other leg, obtain the contact details of the ABBBS, and report the recovery. As it turns out, this bird (#003) was one I ringed as a nestling 15 months ago in the Avon Valley east of Perth, a location ~960 km away from where Peter found it!
While it is sad that the bird was found dead, it is wonderful to have obtained the information about it travelling such a huge distance, considering this was only the third wedgie marked as part of the current colour-banding study. This recovery is now the longest movement recorded (by ringing/banding) for a Wedge-tailed Eagle, with the previous longest distance of 821 km being recorded in 1965 after an eagle banded in Canberra during 1964 was recovered in Cunningham, Queensland, after being shot. It is truly amazing to continue learning how far juvenile birds can move over such (relatively) short periods of time. Thank you so much Peter for your fantastic contribution to eagle research! I'm hoping that this discovery will inspire others to sharpen their 'eagle-eyes' and make more reports of banded and colour-banded wedge-tails - dead or alive!
Sunday, 29 January 2017
I've recently returned from Tasmania where I spent the last 2 weeks volunteering with University of Tasmania student James Pay, who is also studying Wedge-tailed Eagles for his PhD. Some of James' work has involved satellite-telemetry, so I was thrilled when he gave me the opportunity to visit Tassie and assist with the attachment of transmitters to juvenile eagles, something I have been slowly gaining experience doing since Wallu was satellite-tagged in 2013.
More information is coming soon, but for now I wanted to post a few images of the magnificent bird that is the Tasmanian Wedge-tailed Eagle (Aquila audax fleyii), a subspecies of wedgie that, as I was totally amazed to discover first-hand, is so much bigger than its mainland cousin!
|Tasmanian Wedge-tails are normally very wary but this female was an exception to the rule.|
|The eagle's habitat in this southern-most part of its range is usually tall Eucalypt forest.|
|Eyries like this one built in a tall Mountain Ash (E. regnans), are very camouflaged in the canopy.|
|The characteristic pale head and dark bill of a juvenile Wedge-tailed Eagle.|
|Woldja, an 11-week old Tasmanian Wedge-tailed Eagle that I was thrilled to capture.|
|Bill Brown holds Woldja while James Pay fits a harness-mounted satellite transmitter to her back.|
|Woldja's feet were eNORmous (nearly the same size as my hand!) - an adaptation for taking the larger prey animals like possums and paddymelons found in Tasmania.|
|All juvenile eagles have a pale head but Woldja's was an incredibly beautiful blonde colour.|
|A beautifully calm 8-week old Wedge-tail with a transmitter being fitted.|
|The incredible tree-climbing skills of Dave James allowed access to some very high eyries!|
Thursday, 5 January 2017
As the warmer season of Birak takes shape and rising thermal air-currents become more frequent, last year's Wailitj / Wedge-tailed Eagle fledglings are beginning to gain experience in the sky. My local eagle Yirrabiddi (above), who was named by Noongar elder Noel Nannup when she was satellite-tagged in late November last year, has made wonderful progress since she first fledged in early December. Below is a photo diary of her progress, which shows her well on the way to living up to her beautiful, magical name, that translates to 'trail in the sky'!!
When I checked Yirrabiddi just after fledging, she sat confidently on a sturdy limb on the outer reaches of the nest tree.
A week later I found her perched in a tall Marri about 50 m from her eyrie. She only remained perched for a minute before launching on her massive wings.
When I followed her flight path, I was amazed to see Yirrabiddi perched high in a live Jarrah tree at the edge of the open paddock near the centre of her natal territory. You can see her golden head glowing in the beautiful afternoon light.
Before I had a chance to step into the clearing, she took off again and set sail in a long glide across the paddock. A mob of Yonga / Western Grey Kangaroos were grazing in the open, and it was incredible to see several react to the oncoming eagle by standing up tall and throwing their arms skyward. Barely able to fly (let alone hunt!), she is not yet a threat to them at all, but her parents are frequent hunters of this mob, especially the smaller joeys like the one pictured here.
Just after Christmas I visited Yirrabiddi with friend and fellow Parkervillian Brendon Gough, who kindly gave me easy access with a lift on his quad bike. We found her perched near the nest again, sitting proudly in the golden sunlight, with the antenna of her PTT just visible.
We watched as she made a confident flight to a tall perch tree over 1 km from her nest. I managed to sneak around behind her and snap this photo, in which you can just make out the PTT between her shoulder blades, partially covered with feathers.
Yirrabiddi took to the wing once more, but this time really showed me what she was made of! Instead of making a direct flight back towards another perch, she glided into a clearing above the paddock, then began flapping powerfully and wheeling around in big circles, taking advantage of the strengthening westerly wind to gain height.
It was truly amazing to think that this bird, which I had seen as a tiny white nestling only months earlier, was now performing some of the most powerful flights in the animal kingdom! I can't wait to continue following Yirrabiddi's movements as she makes further progress and leaves even more magic trails in the sky.
Thursday, 1 December 2016
The rapid growth of Wailitj / Wedge-tailed Eagle nestlings never ceases to amaze me. The above photo was taken in mid-September, when one of the Perth Hills nest sites I regularly monitor celebrated the arrival of a new nestling. This discovery was particularly exciting as the eaglet's mother, a 'new' immature female, was first recorded on this territory in 2015 and this was her first ever breeding event! In this photo the eaglet is only 2 days old, and has hardly a hint of predatory bird about it.
One day short of being a fortnight old, this eaglet had more than doubled in size, but still maintained its white, fluffy appearance:
Nine weeks later, however, the same bird had made a rapid transformation, and at 65 days old, possesses the powerful wings and piercing stare of a formidable hunter.
This photo was taken early last week when I visited the eyrie to check the bird was fit, healthy and suitable for satellite-tagging. Two days later I was extremely excited to return with my PhD supervisors Trish Fleming and Jill Shepherd, members of Murdoch University's Animal Ethics Committee Moira Desport and Margot Seneque, who have been wonderfully helpful in assisting me obtain the appropriate approvals for my research, and Parks and Wildlife ecologist Geoff Barrett, to fit a satellite transmitter. It was a thrill to be out bush on a fine, sunny Kambarang (spring) afternoon with an enthusiastic bunch of fellow conservation-minded scientists, and share the sights and sounds of an eagle site that I have visited annually since first discovering it 12 years ago. After a short hike through some beautiful open Jarrah forest, we began the scramble down slope into the rugged Helena Valley, wading through shin-scratching patches of granite heathland and peering past the canopies of wonderful Wandoo trees. Soon we were looking onto the eyrie, where a beautiful juvenile Wedge-tail, three days shy of turning 10 weeks old, sat sunning itself.
It wasn't long before I was scaling the nest tree and lowering the juvenile male eagle down in a handling bag to Jill, who held him while I took measurements, applied leg-bands and fitted the Platform Terminal Transmitter (PTT). To continue the theme of using Noongar names for all satellite-tagged Perth region Wedge-tails, and to use a name relevant to the area in which this eagle hatched (Kalamunda, which is also the Shire in which I hatched 32 years ago!), I decided to name him 'Kala', which in Noongar translates to 'fireplace' or 'home/hearth'.
|Moira inspects Kala's beautiful new primary feathers, which are close to lifting him skyward.|
When the transmitter attachment was complete I re-climbed the nest and hauled the handling bag aloft, taking care to ensure its precious contents remained unharmed. Placing Kala back on his nest allowed me a quick glimpse of a recently delivered prey item, a large Karda / Gould's Sand Goanna (Varanus gouldii), whose leathery skin had been partially torn open and some of the head and torso consumed. It was great to know the eagle would have ample food until the next morning, when his father would likely be delivering another vertebrate from the surrounding ecosystem as breakfast. As deep shadows gradually engulfed the valley, we hiked back up the slope and across a large slab of granite, marvelling at the sight of Kala's parents who hung overhead, riding the gentle westerly wind with ease. They had no doubt been watching our every move from the heavens, and I felt excited to know we would soon be able to satellite-track their son when he first soared up to join them.
|Reptiles like monitor lizards can be favoured prey for Wedge-tailed Eagles, especially in arid ecosystems where they are relatively abundant and conspicuous from the air.|
Today, 77 days after he entered this beautiful world, I returned to Kala's eyrie to see how he was getting on. Looking level with the nest from a steep slope behind it gave me a good view of the eagle's back, and I was able to see straight away how he had now preened the harness into his body feathers, which made the PTT sit comfortably between the shoulders, partly shielded by scapular feathers and almost invisible. Photos of newly attached PTTs can create a skewed perception of how seemingly large and heavy these devices are (they are actually relatively small and only weigh 70g), so it was great to be able to capture a few images of a 'settled in' transmitter, which accurately reflects how it looks on the eagle after it is released.
|The PTT aerial casts a thin shadow across Kala's left scapular feathers.|
As I walked down towards the base of the nest tree, Kala hopped over to the edge of his eyrie, glancing back at me, forward across the valley, then back at me again. I decided to sit and watch, fully aware that my presence had prompted this evasive behaviour, but eager to observe him for a few moments and see if I could guage how close he may be to that first big moment. I was transfixed at the scene in front of me. Kala continued to head-bob, looking across the valley, and shuffling as gentle gusts of wind attempted to unbalance him. Suddenly he leaned forward and launched onto a large limb, then clambered up and away from the eyrie, continuing to survey the valley scene before him. My anticipation grew. The nest-tree glowed in magic light from the season of Birak's first setting sun.
Another gust of wind, slightly stronger this time, prompted Kala to partly open his wings, still shuffling on his legs, but gripping firmly with his mighty talons. More head-bobbing. Then another leap forward, this time onto an even thinner branch that probed out into the valley, placing him further away from the eyrie. I could feel the eagle's keenness to fly. I knew if I turned around to walk away, I would miss something special. More peering across the valley, like a nervous human waiting to take the plunge on their first ever bungee-jump. Then suddenly, with one last glance back at me, he stared forward at an unknown point on the hill opposite his eyrie, leaned forward, squirted a jet of white back at the nest tree, then spread a mighty wingspan against the open air and threw himself at it. A faint sound of several powerful wingbeats reached my eardrum, and Kala sailed downwards and outwards, disappearing behind some foliage. This was it. Kala was airborne!
Kala is the third juvenile Wedge-tailed Eagle to be satellite-tagged in the Perth Hills this year. More information about the others, and their progress, will be uploaded as it comes to light.