Diary of a Hills Backyard: The physics bending bee (Jan 2021)

I was taking a couple minute break away from work and the computer screen and wandered outside into a beautiful day. The sun was shining past puffy white clouds as they raced along the blue sky highway. Out of the corner of my eye I noticed something zipping about one of the emu bushes. Immediately I knew it was a Blue-banded Bee. The day before, quite possibly the same bee was buzzing around the same bush. Its movement so fast it almost looked like it teleported between spaces. At the purple tube flowers, the bee stopped midair to inspect, its body so motionless that everything else seemed to orbit around it and that it had stopped in time. So still it seemed, at least momentarily, that you could lean in close and inspect every last detail of its intricate features. All except the wings of course, which beating unfathomably, were barely a blurry distortion of space.

I extended my break and sat down to watch the bee for a while, a bee that appeared to bend the laws of physics and had harnessed quantum mechanics for its own accord. After a little while I noticed a pattern in it behavior. When the sun shone through the clouds the bee was out assessing flowers, occasionally stopping in for a visit. When the clouds came over the bee seemingly disappeared. For one of these brief moments of cloud cover, I saw the bee settle on a kangaroo grass stem, mandibles firmly clamped to the stem, legs and body lifted touching only but itself. The sun returned and the bee vanished into the air.

I did a bit of reading and found that foraging activity in bees may be related to several factors including light levels and temperature. There was certainly a reduction in light when clouds passed and temperature dropped noticeably. So it seems as though the light and/or temperature levels where fluctuating above and below the threshold for foraging in this bee. This too may explain the recent phenomenon of finding Honey Bees on the ground. This summer has been comparatively mild and many days have been cool, though sunny. Maybe these Honey Bees are also getting caught out on their foraging expeditions by a brief cold snap grounding them temporarily.

Compared to previous years there is an apparent lowness to the numbers of Blue-banded Bees in the garden. This, I suspect, has a lot to do with the lack of tomato plants, which have been hubs in previous years. So next year I’ll endeavor to both bump up the veggie harvest and provide these intriguing and lightening fast bees with more flowers to forage at.

Blue-banded Bee settled onto an emu bush leaf waiting for the clouds to pass so it can forage.

Diary of a Hills Backyard: Flycatcher (December 2020)

Early on Christmas Eve day I was in the driveway about to drop my son off at his grandmother’s and was vaguely aware of an anomaly in the soundscape that surrounded me. I was too preoccupied to stand around and search for who was making the sound, but around lunch time I arrived home and noticed the sound again. This time, with my mind no longer swimming with things I had to do, I stood with my son by the fence of the paddock across the road listening to the out of place sound. I could hear an occasional bzzrrrt from the large gum trees in the paddock, though after a little while I could no longer hear the call nor see the animal making it. We went back inside, and I did a few jobs around the house and put my son down for a sleep.

I suspected the orator of this new call might be a Restless Flycatcher, though I was more familiar with the scissor-grinder call they use while foraging. Flycatchers are fabled in my mind, a rare, beautiful bird gleaming with a dark blue-black iridescent sheen, and having slightly anomalous features like a wide-based bill and little crest which deviate from the norms of similar sized birds in the area. The flycatchers have suffered greatly from habitat clearance in the Adelaide Hills and are now Endangered in the region. In half a dozen years birding in the hills, I’ve only seen them a few times in one small reserve containing remnant native vegetation. To add to their intrigue, while doing my undergraduate degree, I remember one of the lectures suggesting the scissor-grinder call caused spiders and possibly other tasty morsels to flee from cover so the flycatcher could swoop down and collect them.

Jobs complete and attention undivided, I went back out into the driveway to search again for the mystery singer. To my surprise I could hear the bzzrrrting and the scissor-grinder call being emitted from a tree not 15 meters from me! I bobbed and ducked with my binoculars until I got a clear view of the luminous flycatcher. Having got a good view, I raced inside to get my camera. I couldn’t let a momentous event such as a flycatcher at home be left to my word and memories without conclusive proof. Camera in hand, back into the hallway, I flicked the camera on. Damn, no memory card. Back to the study for the card, then back outside. Mercifully, the flycatcher had not moved far. It was perching in young river red gums and hawking above the dry yellow grass projecting the scissor-grinder call down to the ground with an open beak. I snapped a few photos. Then, moments later, an indignant Willy Wagtail swooped in and chased the newcomer away. I was ecstatic at having seen the flycatcher and a warm glow sat within me, though a little resentful of the Willy Wagtail for chasing it away. However, what more could be expected from the original angry bird, one with the grit to assault a hawk much larger than themselves that would surely eat them if it got the chance.

The next morning, Christmas morning, I awoke to a burgeoning of bird song. Among the peeps of honeyeaters, the lonesome treecreeper and the chatter of parrots, was the incongruity of the bzzrrrting flycatcher. I went outside to find the sunlight as brilliant beams of soft lemon flowing lowly across the hills igniting the dry grass. Very nearby the flycatcher dipped and swooped between our yard and the paddock across the road, perching briefly and illuminated by the gentle sunlight, its satin shimmering. The moment was again shattered by the local residents, White-plumed Honeyeaters who vehemently chased the flycatcher away. Although I’ve seen the white-plumes chase other birds away, often New Holland Honeyeaters, these chases seem less sustained or primed with emotion. Why the flycatcher is so disliked by the other local birds I do not know. This matter will remain a mystery to me and a subject of my mere speculation, though, perhaps not to the honeyeaters and wagtail.

A gentle positive warmth from seeing this lovely creature lingered in my soul for more than a day, a feeling that I lapped up. I am so lucky to have had this encounter, and I hope that someday the flycatchers will return.

Illustration of a Restless Flycatcher perched in River Red Gums by Diana Koch.

This work was commissioned for this blog post in part to pay homage to A Sand County Almanac by Aldo Leopold and illustrations within by Charles W. Schwartz which inspired Diary of a Hills Backyard.

If you would like to contact Diana about her artwork please email dianakoch@westnet.com.au

Talbots Reserve

When I first got into birding many years ago, I would travel around Adelaide visiting different reserves and parks looking for birds I had not seen before. It was such a thrill to see something new. Back in those early days of birding my cousin mentioned a little patch of remnant vegetation out in the Murraylands called Talbots Reserve. My Uncle had been there with a group which was led by a knowledgeable birder. This birder had shown them several interesting and rare birds, many of which we had not seen before. So, without hesitation we decided to visit.

The reserve was fascinating and packed with about six dozen native plant species. There were patches of Southern Cypress Pine rich in greens and standing in their lovely pinnate form. South Australian Blue Gums and Mallee Box Gums thrust their leaves to the sky on twisted and bent branches, though some weighed down by the lurking and uncanny mistletoes which hung their red and green flowers among their own fleshy leaves. The flowers of Sticky Hop-bushes would draw a multitude of insects and the doo-le doo-do of calling Peaceful Doves would waft calmly through the warm air. The reserve did indeed have birds that we had not seen before, particularly species which occupy drier habitats away from the more mesic Adelaide Hills where I spent most of my time. Diamond Firetail Finches with their scarlet rumps, white diamonds on their black flanks and their red becks coupled with a tiny black mask were one of the most beautiful and delicate of the new bird prizes. Then the Restless Flycatcher, attired with a dark satin sheen on the upper parts with brilliant white on the lower, projecting their scissor-grinder call to their yet unseen prey.

A Peaceful Dove perched quietly in Talbots Reserve.

The most memorable new bird I saw was the White-browed Babbler. I remember a group of these peculiar birds jumping around in low dense shrubs with big tails and decurved beaks making an array of interesting noises. Once I got a good look at one, I said to my cousin, “I think that’s a babbler”. At the time I did not fully understand how I knew that. I was not the sort who went through the field guide and knew every bird I could possibly see before I went out into the field. I would go out, see what birds I saw, and check back with the field guide after the fact. When I was five, I got a field guide from my cousin’s family for my birthday. Back then I looked at a few birds in the backyard but did not delve deeply into the avian world. In hindsight, what I think happened that day was that I dredged up information deposited deep in my mind from flicking through the pages of that field guide when I was five, around 15 years earlier. Nowadays, babblers still bring me joy and curiosity when I see them, and sometimes I ponder the workings of my own mind.

I did multiple trips to the reserve over the years and it was only after perhaps half a dozen trips that I began seeing only birds I had seen before. As well as the reserve containing the interesting and new birds, other aspects of the reserve began to catch my attention. The array of plants of various forms, the large ant holes a few centimetres in diameter punctuating the sandy soils at frequent intervals, ferns and occasionally orchids nestled into rocky crevices on granite outcrops, and interesting wasps and other busy insects visiting bushes flush with flowers.

Over these trips something else developed within me. A peacefulness, something almost spiritual related to this place. I found I could stand among the trees listening to the gentle whooshing of the breeze through the leaves and the calls of the plentiful birds and my mind could rest. This place could provide respite from daily life and the ordinary churnings of my mind. I’ve been to plenty of wild places and only a few have really provided me this sensation. I have pondered why this is, and there are several facets.

People: I have never seen another person walking around in the reserve that I do not know. I have some level of social anxiety, particularly in large crowds but also when I am out in the bush and there is someone else walking around that I don’t know. The barriers I put up within myself to deal with social interactions, or the potential of, are costly. To let these barriers fall away is a huge relief.

Space and composition: Talbots Reserve and the reserve across the road are only about 22 ha combined, but I can stand within them on the sides of the low hills and imagine what the whole landscape looked like before much of the land was cleared for agriculture. This is something that is pretty special in these parts as most of the areas have been cleared, at least at some stage.

And finally, sound: the sound of an environment is something that often gets forgotten about, or at least the less conspicuous things, like the rustle of a skink in the leaves or the buzz of an insect flying by. But sound to me is as vivid as sight and often it tells me more about what is going on in a place. At the reserve there are very few sounds that can be attributed to humans. There is a dirt road, though cars pass infrequently. This may seem relatively unremarkable. If you get far enough away surely there are not human derived sounds. However, there could be the rubble of a car off in the distance on some remote track, a plane flying high in the sky or even the vibrating of a wire fence in the wind. It is amazing how far sound travels particularly from highways. On a clear night I hear trucks on the freeway over 2 km from my home. In the bush, I can pick out the high-pitched calls of secretive birds from among the calls of other birds and the wind that others cannot hear. However, my perception of soundscapes has boundaries. In a crowded restaurant, I have difficulty holding conversations because my brain cannot separate the background conversations from those of the people I am conversing with. This can make for some awkward situations and why nightclubs were never a good place for me to meet people when I was younger. At Talbots, though, I can sit and listen to the wind through the trees, the birds calling, with whistles of a Crested Pigeon’s wings as it flutters from its perch, the buzzing of a little black wasp as it inspects a stick, without intrusion.

A female Purple-backed Fairy-wren sits in its nest in a jumble of sticks on the ground in Talbots Reserve.

I recently went back to the reserve after several years of not visiting and the magic has not worn off. Not only were interesting birds doing interesting things, but still I got my moments of peace and tranquillity to recharge. A group of Varied Sitellas fluttered around in their frantic way with their almost needle like upturned beaks collecting food for a nestling that sat in its tiny nest in the V of a dead branch silhouetted against the overcast sky. A female Purple-backed Fairy-wren popped into its nest in a pile of sticks on the ground surrounded by dry grass. Two coloured males diligently bringing food. A juvenile Hooded Robin perched on an old dead tree trunk, which, grey with age, was topped with lime green lichen. And one of the Brown Treecreepers loudly protested our presence.

Brown Treecreeper making in known that we should be somewhere else.

Wild places do not always have to be great swathes of untouched wilderness, not to say these places should not be protected, or even created. But small reserves like Talbots can provide many of the sensations and feelings that wilderness can provide. Additionally, and most importantly, they provide a refuge for the plants, animals and other organisms that live there, a growing necessity in our current world.

Diary of a Hills Backyard: Flies and the spinach plant (November 2020)

It’s the first really nice day we’ve had in a while. It’s a La Nina year and the weather’s been pretty cool and wet for some months now. Normally it’s warmer and drier this late in the year, but everything needs respite and an opportunity to grow and thrive after the hot dry few years we’ve had.

I’m sitting outside by the spinach plant, who’s tiny green flowers are just starting to crack open revealing yellow pollen clad anthers. The air is thick with moisture and a fragrant botanical smell wafts through the air. Among the sun and shade of the foliage, sitting on leaves and stems, or zipping about, are flies. The flies are incredibly variable, perhaps spanning 100 orders of magnitude in mass. The largest, a bulky and clumsy fly maybe a centimeter long with a dark bronzed abdomen and black hairs. Slightly smaller are the iridescent dark green flies with deep red eyes (from the right angle), which are meticulously checking the tiny flowers. Inspecting one of these beauties up close, so close my eyes can only just focus, I see tiny pollen grains stuck to the hairs on its body. Next down the line are the hoverflies, who’s wings, when grounded, sit out like a fighter jet’s, while their yellow and black stripped abdomen bobs up and down. There are smaller hoverflies too, much the same. A brightly coloured lady beetle catches my attention for a moment. Further down the size scale is the darkly iridescent gold fly whose apparent role is to bother the bigger flies by zipping about then landing on them. Its abdomen is a slightly stubby bullet shape which I can’t quite comprehend. I shift my legs to shade myself from the sun to find a much larger fly than any I have seen yet resting on my foot. After a moment’s hesitation, it flees at the disturbance. This fly’s wings sit in a triangular shape above the gunmetal blue abdomen. I focus back on the spinach plant. There are numerous tiny flies as varied as the big ones which include some fruit flies and flies that are as big as two dots made by the pen I am writing with. I can barely see their form, let alone colour, though a fruit fly lands close in view revealing its cream body and racing stripes running down its length.

Some may want to rid the world of flies, and sometimes I do too. Well at least the ones that get into my eyes. However, these flies on the spinach plant are not the ones I have qualms with. These flies give me joy at their antics, wonder at their fine details and beautiful colours, and make me ponder the diversity of life. If half a dozen species of fly can exist in this microcosm of a spinach plant in this one moment of time, the number of other species that exist in the world now and throughout history is incomprehensible. These flies shine a tiny light on the interconnectedness of the world. They sip the nectar from the flowers and plant that has sucked energy from the sun. They transport the pollen to fertilise another flower, and then, if unlucky enough, might get snapped into the bill of a fairy-wren, which then feeds the fly to its nestling who may one day grow old and snap flies of their own.

Diary of a Hills Backyard: Big Hawk, Little Hawk, Compassionate Hawk (January 2020)

During the time we’ve lived here I’ve got many short glimpses of hawks. They occasionally land in trees in the backyard, or drift and swirl through the air, wings unmoving, before disappearing as promptly as they came. I would scramble to get my camera or binoculars so I could confirm their exact identity, but never fast enough. There are two possible hawks in the area, the Collared Sparrowhawk and Brown Goshawk. They look remarkably similar especially when getting only distant views. Although female goshawks are much larger than either the males or sparrowhawks, the diagnostic differences between species come down to things like position of the first knuckle of the middle toe, the shape of the tail and where the powder blue is on the beak. There are people out there who can tell the different between the narrow silhouette of this or that raptor in the dwindling evening light from a mile off, but I’m not one of those people. However, this month was more fruitful for my hawk identification attempts.

In the evening of New Year’s Day, while sitting in the lounge room I heard the rising franticness of alarm calls which signals the arrival of a hawk. Often the hawks fly over before disappearing down the valley, while the chorus of alarm travels with it. Every bird valuing its continued existence and of a size that would make a delectable dinner dive into the depths of a bush or tree. Today though, the alarms remained, along with the occasional “kek” emitted by a hawk. I postponed my dinner to investigate. I found up in the branches of a stately old elder gum, a hawk pulling the feathers off a decapitated, bloodied bird carcass. I thought the ill-fated bird may have been a Crested Pigeon but couldn’t be sure as they were so high up in the tree. Even with some distant photos, the hawk’s identity could not be resolved. I consulted a friend who suggested that if the unfortunate bird was a Crested Pigeon then this was a female goshawk. The Crested Pigeons had nested in the backyard and had a bundle of sticks, which suffices as their nest, hidden in a bush not far away. The Willy Wagtails were none too happy and were complaining fiercely, ensuring the hawk was under no illusions about that fact. The wagtails were game enough to thrust their sharp claws into the hawks back, ruffling and removing some of the nicely manicured feathers. The wagtails were such a pestilence that the hawk moved to another perch in a lumbering flight hauling its meal. The New Holland Honeyeaters, not as game as the wagtails, sat carefully watching the lethal predator, keeping a safe distance.

A couple of weeks later, on a beautiful evening the hawk alarm calls began again. This time the identity of the perpetrator was more obvious, as the hawk landed on a low branch in the backyard with its prize. This was a Sparrowhawk and much smaller than the bird I’d seen previously, confirming that both hawk species stalk the skies above our house. This time a young White-plumbed Honeyeater was the hawk’s sustenance, feathers plucked before the meal began. The Willy Wagtails were again making their disdain felt. Even a Black-faced Cuckoo-shrike joined in the beratement of the hawk, swooping low above its head.

Collared Sparrowhawk with a young White-plumed Honeyeater

Though the scene of a hawk with dead bird in its talons maybe challenging to some, like seeing a pride of lions take down a wildebeest on the African plains. These animals are symbols of strength, agility, speed, cunning and determination in human culture. We should not forget why these animals have come to symbolise these attributes, and remember that the powerful predatory symbols we idolise are not the compassionate hawks who let their meals fly away.

Diary of a Hills Backyard: One smouldering tree (and a hundred more) (December 2019)

On the morning of the 20th of December a bushfire broke out in catastrophic weather conditions approximately 20 km from our home. The fire moved quickly razing much in its path including trees, bushland, houses, sheds and animals. By early afternoon we had evacuated our home as the fire headed directly for our town. Fortunately for us, but not so for many others, the wind changed direction and took the fire with it. My uncle’s farm was not so fortunate, and the wind took the fire there and beyond. Luckily, they were safe, as well as the house, sheds, hay, and by some extraordinary luck, the sheep and cattle.

After a couple of days I made my way into the fire ground to help fix fences to keep stock in. One thing that struck me was the number of big ancient-looking gumtrees that caught fire and collapsed, or were still on fire. The fire had got into the exposed heartwood and in some cases smouldered or burnt for weeks. Many of the younger gums remained relatively unscathed (I’m unsure if some may die later). One smouldering River Red Gum stood out to me. Broad-based, narrow topped, very gnarled. It had half a dozen small hollows on the side I could see.

The gnarled old gum still smolders four days after the fire went through surrounded by blackened bare ground.

In the canopy, a pair of Crested Shrike-tits foraged among its parched leaves. Shrike-tits are fascinating birds. They sport a little black and white crest which becomes erect when something catches their attention or they are in a dispute with some other bird. Though this is not to say they get into raucous encounters often. Most of the time they are unobtrusive, flitting through the canopy looking for food. Sometimes the only reason you know they are there is because you hear them tearing bark off trees with their can opener-like beaks. We have a pair that lives around our house and I know when they are about because I hear their little giggling or chuckling-like call. If you aren’t paying attention to the soundscape you could easily miss them. In addition to their fancy head and crest, they have a black or olive bib (depending on whether male or female, respectively), a yellow belly, and an olive back and wings making them a rather striking looking bird. Shrike-tits are vulnerable in the Mt Lofty Ranges and I’ve been told they have home ranges as large as 100 ha, so even if you are within their territory you still might not come across them often. They are no doubt my favorite backyard bird and I always get a thrill from their presence, no matter if I just hear them giggling or see them up close splashing in the birdbath.

An old photo of a Crested Shrike-tit which wrenched open this tube of bark to extract a spider. His handy work can be seen at the top of the bark.

Pondering the smoldering tree with the shrike-tits reminds me of the gumtree in our backyard. So many things happen on that one tree. Tiny psyllid insects sit on the leaves producing their waxy sugary little domes (lerps). The lerps attract Striated Pardalotes, who specialise in such delicacies and have nested every year in a small hollow in one of the branches. When its been a good year and the tree is flush with leaves the White-plumbed Honeyeaters build their nest within the green drooping masses. Willy wagtails, more confident in their ability to fend off undesirable company, place their nest on a exposed dead stick. Ants march up and down the trunk. Spiders face off with each other on a sunny day, seeking refuge under the bark when disturbed. And of course the shrike-tits ripping bark off to find a juicy invertebrate. By night Ring-tailed and Brushtail Possums stride along its branches looking for a vegetarian feast, where a Boobook or Tawny Frogmouth may have alighted only moments before. There are so many interactions between this one tree and the organisms around that it could be someones life’s work to record all such interactions and never record all that there is to record.

These fires, by burning down these trees, are erasing the history of the landscape, and with increasing frequency and intensity of fires our landscape will become poorer and poorer. With each tree lost we lose the history each tells in it gnarls, twists and hollows. It represents the disappearance of a node in a complex web of interactions that each tree has. When we loose hundreds of these magnificent trees in one brief inferno, it immeasurably increases the value of those that are left. We should cherish and protect those that are left, and help propagate more of these scribes of the landscape and nodes of complexity.

Diary of a Hills Backyard: The weed patch, and always listen to what fairy-wrens have to say (because your life might depend on it) (December 2019)

This year has been a busy year, with our son arriving, and plenty of travel and work. This busyness resulted in the garden being somewhat neglected and weeds in some areas reaching lofty heights. Towards the end of the year we got onto most areas except one of the slopes by the back veranda. We noticed a couple of months ago the Superb Fairy-wrens collecting nesting material and taking it into the weed patch. The fairy-wrens did indeed build a nest and successfully fledged three chicks, resulting in the weed patch being conserved temporarily. In December, the fairy-wrens built another nest, and were again successful in fledging chicks.

As well as providing refuge for the fairy-wrens, the patch also acted as a fort in which a rabbit, dubbed the “Nibbler”, made its home. The Nibbler has damaged new plants we put in and, along with blackbirds, dug small holes in the garden. The Nibbler remains at large, but in the hot weather I have called a truce and I have ceased my attempts to catch it.

Grasses make up the greatest proportion of the weeds in the weed patch, and have matured and dried producing copious seeds. A few weeks ago I noticed the appearance of mouse holes nearby. Given most other areas in our yard and in the paddocks next door have been mown or grazed, the weed patch probably has a higher abundance of seeds than elsewhere. Good encouragement for mice to move in. The next logical resident to appear in the weed patch is one to keep the mice in check.

One day, in the throngs of a heatwave, I was outside trying to keep plants hydrated, and the fairy-wrens and New Holland Honeyeaters alerted me to the arrival of the new weed patch resident. I went to investigate the peeping alarm call, which is less frantic than the one used for a hawk. I peered under the bushes and over the weeds, looking at where the birds where looking. It wasn’t long before I found a meter-long brown snake sliding up against the fence, which promptly disappeared at my arrival. There have now been four occasions that fairy-wrens, mainly, and New Holland Honeyeaters, have alerted me to the presence of snakes.

Always listen to what fairy-wrens have to say, your life might depend on it.

Highlights of Mt Isa via Birdsville Track 2019: Part 2 Grey Grasswrens and the green outback

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A Grey Grasswren (Subspecies diamantina) on Birdsville Track hiding in saltbush.

Grey Grasswrens are somewhat of a legend in my mind. They are a mysterious, elusive creature that lives in the remote arid interior of Australia where the tales and names of early European explores abound. Grey Grasswrens are peculiar among grasswrens in both looks and habitat. They have striking black and white markings compared to earthy browns, rufous and greys of many of the other species, and they live in tangled clumps of lignum (sometimes with saltbush), compared to hummock grasses (Trioda), chenopods (e.g. saltbushes, blue/black bushes) and canegrass that the other grasswrens reside in.

In 2017 we were fortunate enough to have a wonderful encounter with these birds. However, this year when we went looking for them again on Birdsville Track, we where blown away by the experience. The floods that had come down from Queensland fueled by cyclones had reached out and turned the Grey Grasswren’s habitat green and spurred on abundant new life. There were Crimson Chats foraging, small flocks of brilliant green budgies flying over, Zebra Finches and Diamond Doves drinking from a small pool of muddy water, all surrounded by a verdant green carpet of herbaceous plants speckled with the bright colours of wildflowers. Within minutes we heard the grasswrens calling from all around us, from this or that clump of lignum or saltbush. We waited and wandered around quietly and after not too long the grasswrens were zipping between bushes and climbing to the top of clumps of vegetation to have a look at the visitors on their patch. It was clear that the grasswrens, like the other birds, were benefiting from the floods, as we saw a fledgling hopping around on the ground with its still as yet ill-defined markings. It was wonderful to see these grasswrens again and their habitat in such fine condition. It has been a bucket list item for me to see the desert in bloom and this trip certainly ticked that box.

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Wildflowers blooming in Grey Grasswren Habitat.

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Crimson (top) and Orange Chats (bottom) were some of the more colourful outback residents benefiting from the floods.

Grey Grasswren habitat 2018
Grey Grasswren habitat on Birdsville track in 2017

Grey Grasswren habitat 2019
Grey Grasswren habitat on Birdsville track in 2019 after flooding

 

Highlights of Mt Isa via Birdsville Track 2019: Part 1 Eyrean Grasswrens

A brief intro.

Each year Ali and I do a longish trip somewhere around Australia. This year (2019) we decided to head up to Mt Isa. ‘Why Mt Isa?’ I hear you say. Well Mt Isa and surrounds is home to two species of grasswrens, the Kalkadoon and the Carpentarian Grasswren. This year’s trip was going to be different for several reasons. The biggest was that we had a new team member for our adventure, Otto our four month old son. We were also doing a three week trip, rather than the usual two weeks, and we would be heading back from Mt Isa along the same route as we got there, along Birdsville Track.

Highlight 1: Eyrean Grasswrens

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An Eyrean Grasswren with grasshopper west of Birdsville

Eyrean grasswrens live on the top of sand dunes in the Simson and Strzelecki Deserts where there is plenty Sandhill Canegrass to hide among. They are very much a boom and bust species who’s numbers dwindle when conditions are dry and the vegetation on the dunes deteriorates, but in good seasons you almost can’t walk on a dune without tripping over them.

We started searching for Eyreans on the southern part of Birdsville Track, and were successful in finding them. However, the dunes were relatively dry and the grasswrens were proving elusive. The canegrass on many of the dunes was very dry and grey despite there being some wild flowers present (certainly in less favorable condition than back in 2017 when we were there last). Despite this, further north the dune vegetation was in better condition and Little Red and Big Red dunes west of Birdsville were looking good. We saw Eyreans at both Little and Big Red, and the ones at Little Red were carrying around grasshoppers to feed to their young. However, one Eyrean grasswren on Big Red provided me with one of the most outstanding grasswren experiences I have ever had.

I spotted this Eyrean a bit further along the dune from where I was, and I went and followed it quietly. I managed to get very close to it, within a few meters, while it was foraging in a clump of canegrass. I could hear it moving around and it was well aware of my presence. It would forage in a clump of canegrass, come out to the edge for a look around, then move swiftly to the next clump were I followed it too, quietly and carefully. For about 10 minutes this went on, and it was fascinating to watch the bird so close, at one point picking up a meal worm looking insect. After the grasswrens was finished in one clump of canegrass, and to my absolute surprise and awe, the Eyrean hopped out into the open about 1 m from my leg and watched me for several moments. Grasswrens are generally very secretive and will keep their distance watching a viewer from within bushes (where you can’t see them) or perching several tens of meters away to have a very quick look at you (if you’re lucky). And there was one right there! By my leg! In the open! It was absolutely wonderful seeing this animal so close, seeing the detail in its feathers, its face and the way it stood in the sand. Great pictures are one thing, seeing the details with your own eyes and being so close to such a generally elusive animal, is just next level. I thank that little grasswren for proving me with one of the best wildlife experiences I have had in my life. I wish it all the best for its future endeavors.

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Thank you to this little Eyran Grasswren for proving an outstanding wildlife experience, Big Red dune near Birdsville.

The Subterranean Diving Beetle

P. macrosturtensis K. Jones and M. Haase
The subterranean diving beetle Paroster macrosturtensis from the Sturt Meadows aquifer in Western Australia. Photo: Karl Jones and Mark Haase.

The Goldfields region of Western Australia is covered in arid shrublands, where mallee eucalypt and acacia bushes reach into the sky in their lowly fashion, and the yellow afternoon sunlight spills through bluebushes, illuminating the red sandy soil. Vibrant wildflowers, including bush tomatoes, mulla mallas and daisies, spring from the ground, showing off iridescent purples, yellows, and whites. Eremophila bushes provide watchtowers for dusty White-fronted Honeyeaters and a drink of sugary nectar from the abundant purple flowers. However, this area was not always this dry and arid. Once rivers flowed through the region, filled with numerous aquatic animals, however, as Australia became more arid over millions of years these surface waters began to dry out. But now, below the red sandy surface, water still resides and some of the ancestors of those surface dwelling aquatic inhabitants remain.

A scientist wanders along the sandy surface looking for a PVC pipe sticking out of the ground. These pipes line boreholes drilled into the water filled aquifers formed by porous calcrete rock. The scientist has half a fishing rod with a reel, and a small plankton net attached to the line which is dropped down into the borehole and the water below. Down in the water, numerous small creatures zip about, swimming, or crawling along the pale creamy coloured calcrete rock. There are numerous types of animals, including various crustaceans like amphipods, copepods and charismatic haloniscus, as well as tiny diving beetles. In this aquifer, the Sturt Meadows aquifer, there are three species of diving beetle, Paroster macrosturtensis, Paroster mesosturtensis and Paroster microsturtensis. The largest, P. macrosturtensis, is only 4.2 mm long. These little beetles look odd compared to their surface dwelling cousins and have many traits typical of subterranean animals including reduced or no eyes, a lack of pigmentation, long hair-like sensory structures, and they have lost their ability to fly.

The scientist is looking for these beetles because their presence poses an interesting question. How do these beetles breathe in these underground waters when they may not be able to find air? Most surface dwelling diving beetles go to the surface to collect a bubble of air under their wing covers (elytra), which they take underwater to supply oxygen for their dive. However, the surface beetles need to return to the surface when the oxygen runs too low in the bubble. The subterranean beetles may not have access to air because they may get stuck in crevices or cracks underwater and there may not be an air-water interface over much of the aquifer because of water infiltrating into the soil and stone above the aquifer.

The subterranean diving beetles overcome this problem by using cutaneous respiration, breathing through the “skin”. Oxygen diffuses through the water to the beetles’ surface, and then through the hard cuticle either into the gas-filled respiratory system, the tracheal system, or directly through and into the tissues and cells to where the oxygen is needed. The subterranean beetles, P. macrosturtensis and P. mesosturtensis and a species from a different aquifer, Limbodessus palmulaoides, also differ from some submergence tolerant surface dwelling diving beetles, in that they do not have microscopic structures on their surfaces like pores or hair like-structures to help oxygen diffuse into their bodies.

There is, however, a trade-off for these subterranean beetles between body size and being able to successfully use cutaneous respiration. Western Australia has the most diverse assemblage of subterranean diving beetles in the world with more than 100 described species from approximately 50 isolated aquifers, but none of the beetles are greater than 5 mm long. As the beetles become larger their body surface area relative to oxygen demand decreases, and their cuticle becomes thicker and more resistant to oxygen diffusion. This makes it more difficult for the larger beetles to successfully utilise their environment by limiting the amount of energy that could be used for activities like finding food and mating.

This blog post is based on research that Roger Seymour, Steve Cooper and I conducted during my PhD and is now published in the Journal of Experimental Biology. See here for the full research paper: https://doi.org/10.1242/jeb.196659

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Many subterranean diving beetles are found in the Goldfields region of Western Australia.