Monday, August 2, 2021

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HomeIssue 10A touch of light: citadels of the Tanami

A touch of light: citadels of the Tanami

By MIKE GILLAM

Photos © Mike Gillam

Memories of last summer are agreeable, for me the best on record. Thank you La Nina. Autumn continues, protracted and the epitome of human comfort. The vociferous birds and basking lizards are in heaven.

At 17 C the early morning sun is delicious and I begin to appreciate that reptilian fondness for lingering, body pressed flat against the surface of a warm rock. The sensation of a suboptimal body temperature being raised by external heat is bliss.

Until I’ve fully absorbed this early morning pleasure, my brain and body seek sunlit distractions, refusing to be shackled to the writing desk. In a semi trance, I invest my time instead watching birds, appreciating the light and the warmth. 

A great many birds are enjoying an extended breeding season courtesy of the rain and a bounty of seed and insects that followed. Grasses are heavy with ripe seed that will remain available to granivorous birds for months after it has fallen to the ground.

Even now budgerigars are exploring river gum hollows so it looks certain they will breed once more. Remarkably the Yeperenye caterpillars are still about searching for food, their numbers like the hawk moths dwindling now as winter approaches. The battalions of small pesky ants have retreated from the cold and even the flies are subsiding.

 

Last month in the Tanami I drove very erratically and slowly through a blizzard of birds, mostly diamond doves, including innumerable naive fledglings, in numbers I’ve never seen before.

Rounding a bend in the mulga we flushed a feathered huddle engaged in some surreal, middle of the road, ritual. As I braked the crowd of several hundred doves rose in panic. I stopped and climbed onto the roof rack in the hope they might return and reform.

After five minutes they did return in lesser numbers and this gave me the opportunity to take some photographs and try to analyse what they were doing. This unusual aggregation, joined by a dozen or so zebra finches and a couple of curious budgerigars, was also beginning to attract the attention of brown falcons so the flock dispersed in panic and reformed many times as I watched. Why were they leaving the security of the dense mulga on either side of the road and risking such exposure to predators?

The doves seemed to understand the falcons were not really serious, having already feasted on the carnage of road kill doves; both predator and prey were simply going through the motions.

Heads down, the doves were clearly eating something but even with the benefit of a long lens realisation came slowly. Tickweed and a variety of native grasses had produced a profusion of tiny seeds, now gathered together by a strong wind and captured in the troughs of the heavily corrugated road.

The prevalence of the diamond doves and flocks of insectivorous woodswallows added hours to our journey and our itinerary was soon in tatters. We only just made our chosen campsite before sunset, a sand plain with unusually high densities of knee high termite mounds. 

In December 2020, at the end of the three year drought, I’d photographed the lightly vegetated site from a height of about 15 metres using a drone. Following recent heavy rainfall, I anticipated a rich infill of desert foliage; flowering spinifex and Sennas, tendrils of intertwined legumes, rosettes of succulents and even sedges.

With unique termite mound arrangements providing perfect photo points I’d planned to fly the drone once more to capture this exuberant desert to accompany the earlier impoverished image. Wrong footed, I wasn’t prepared for the dense metre-high vegetation that dominated the landscape of now invisible termite mounds.

The sun waits for no-one and we decided to continue our journey, the drone undisturbed in its box.

Sunset brought little respite with spotted nightjars, a common feature of this desert, trawling for insects that crowded around the vehicle headlights as we swept through the darkness – just slow down and enjoy the ballet.

In drier times, the nightjars are an even greater hazard because they seem to spend much more time on the ground, bounding after their prey and flying up at the last second as vehicles bear down on them. On one such occasion I had the opportunity to marvel at the incredible beauty of a nightjar’s plumage and examine the elongated whiskers at the corners of its wide beak, so useful in detecting prey as the hunter lunges, mouth agape.

The bird in hand had collided with the vehicle bonnet, regurgitating a large hawkmoth on contact. After a period of rest, I encouraged it to consume the moth and we parted company, both of us a little wiser.

Apart from the blue grey clumps of sprawling melaleucas and the occasional spindly dogwood, the landscape was eerily treeless. Several hours later we located the next campsite, a vague side track linking to the gas pipeline that supplies the Granites gold mine. Here we settle down for the night amongst large brooding shapes.

An hour after sunrise, a heat haze transformed the vista of giant termite mounds. Aided by the bare expanse of a rapidly heating Tanami track, distant mounds were distorted and stretched into tall vertical columns.

The mirage recalled a time before trees, when giant fungi dominated the landscape. The genus Prototaxites occurred worldwide from 420 to 350 million years ago and fossils measuring eight metres in height and 1.5 m. width have been recorded.

I took a photograph across the shimmering plain, termite mounds in the foreground  appearing to dwarf a road train and the stretched forest of columns in the background (image at top). For further information on these impressive fungus monoliths I can recommend this article.  

The Tanami Desert is a highly variegated landscape, both striking and subtle, complex and parched. Through the windscreen of a LandCruiser, travellers often complain that it’s a boring desert, its subtlety lost on them as distance and corrugations take their toll.

Certainly there’s not much elevation to satisfy those who only have eyes for sensational mountain peaks. If you can’t name the plants and recognise them as old friends, then the essence of the Tanami will escape you.

There are of course occasional modest creeks, ridges and extensive shallow basins, colonised by impressive trees such as river red gums, ghost gums and bloodwoods. Most prominent is the desert walnut, Owenia reticulata, straight trunked, wide canopy with broad leaves and dense green shade, not to be confused with the typically multi trunked black gidgyea, Acacia pruinocarpa.

Owenias look completely out of place in the arid zone. They have the characteristics of a subtropical relict clinging to the margins of paleodrainages, a stately signifier of ground water in much the same way as desert oaks find shallow groundwater in the sandplain and dune deserts further south. We collected some seed from the roadside and included a bag of leaves and soil, replete with fungus spores we hoped. 

Equally impressive are the huge termite mounds constructed by Nasutitermes that also favour the relative moisture stability of paleo environments. Close examination of the three+ metre high mounds revealed a honeycombed surface with galleries left open at various points, presumably ventilation intakes and outlets that are important for drawing cooler air from the subsurface.

PhD research by geoscientist Anna Petts, studying with the School of Earth and Environmental Sciences at the University of Adelaide reveals that mound building termites can recover material from a depth of up to 30 metres.

After dark and with the aid of a head torch I searched for life on the surface of the still warm mounds. Spotted geckos, Gehyra pilbarensis were very abundant on some mounds, the tiny insects attracted to our lights encouraging the small hunters to reveal themselves (image at bottom). The geckos are not without enemies and I could well imagine the nightjars snatching them expertly from the surface.

Cave crickets and occasional striped legged spiders were also observed but after searching many times over the years, I’ve been unable to locate the mound dwelling pygmy python, Antaresia perthensis that occupies similar environments in Western Australia. In fact, this story carries so many apologies and conspicuous gaps that I’m beginning to wonder if my decision to write is a decade premature.

During the day I’d encountered a spectacular pygmy goanna, Varanus acanthurus living in a short burrow beneath a fallen chunk of termite mud but I was taunted by the presence of regularly used ‘toilet’ sites belonging to a mystery termite mound lizard. That is, until I mentioned my confusion to Herpetologist, Greg Fyfe.

He suggested a robust and spiny skink might be responsible. Egernia depressa inhabits mounds in neighbouring WA and Fyfe has anecdotal evidence of the species observed by an Alice Springs Desert Park contractor who worked in the area.

On the journey home we continued to search for viable images among the termite mound landscapes. Clouds were building in our wake and the endless distractions of birds, lizards and plants at the roadside slowed our progress. We were plagued by windy conditions and a reluctant drone sending plaintive messages about unacceptable working conditions and requesting immediate return to terra firma.

As light levels fell in the late afternoon worker ants began to frantically move eggs and pupae to a new location while a high speed spider worked furiously to sandbag its burrow perimeter with silken packages of sand hauled up from the depths.

The spider was an old familiar and with two flashes at the ready I waited crouched over its hole. Every couple of minutes it emerged with a fresh package. I immediately depressed the shutter and more often than not, I missed most of the action, barely capturing the spider on its return sprint from the outer reaches of its flood levee.

We stopped at one point for a couple of hours to stalk and photograph a pure white bird flying within a mob of masked wood swallows (above left). I’m still not sure if it was a true pink eyed albino but the white wood swallow, not to mention a black and tan dingo variant were unexpected compensation for an agenda mostly unrealised.

Every square metre of the landscape was crowded with multiple species of plants, many in flower. A week of freedom from the smothering buffel grass plague had lifted my spirits greatly.

Pristine desert country after rain is a good place to be reminded how little I know and what we have already lost in Centralia. I fantasise about the future rise of virulent pathogens that will take out buffel grass.

 

Recently in this series:

A touch of light: intriguing slime mould

For the complete series of “A touch of light” go to the Features button on the home page menu bar.

 

1 COMMENT

  1. Only a person who has spent years immersed in the landscape in all seasons, and trying to draw conclusions from the hundreds of hours of painstaking observations, could produce photographs and commentary such as those in this series “A touch of light”.
    Lucky are we who receive them!

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