Introduction
The Thompson River expeditions are explorations of koalas and their habitat in the northwestern extent of their range.
Queensland koalas occur as a widespread low density population although local high density populations occur in places. They are found in moist coastal forests, in southern and central western sub-humid woodlands and in the semi-arid west (Melzer et al. 2000).

The western, mostly semi-arid, populations are poorly understood reflecting their regional remoteness and low settlement density. The region is relatively uncleared and the contemporary koala distribution is considered to be the least disturbed by European activity and more reflective of habitat and environmental factors than koala populations elsewhere. Further their occurrence at the north western extent of the species distribution is likely to have produced distinct genotypic and phenotypic characteristics. Consequently these populations are of scientific interest and are considered likely to be of national conservation significance (Sullivan et al. 2004).

There have been few studies of western koalas. Gordon et al. (1988) described the koala’s dependence on riverine drought refugia and vulnerability to extreme events in inland southern Queensland. Munks et al. (1996) showed an association with the better watered riparian systems in north western Queensland. Sullivan et al. (2003, 2003b) found a similar pattern with the distribution associated with, and diet derived from, the riverine communities and also with headwaters and springs in adjacent ridges, mesas and plateaus. These populations appear to be widespread and low density (Sullivan et al. 2003b, 2004). Indeed, Munks et al. (1996) did not sight a koala during their study. So understanding the koala’s population dynamics and conservation biology in this environment is difficult at best.

There are indications that the koala’s distribution has contracted eastwards during the 20th century (Sullivan et al. 2003, Gordon et al. 2006) although the reasons are unclear.

Travelling the country
This was the third expedition to the Thomson River over the last eight years. Previous trips were in early spring 2000 and 2003. On those occasions the team travelled to Longreach and then up the river via Muttaburra to Iona Station and Moorrinya National Park. This expedition diverged from that route. We were able to visit a property in the Tambo district. So our itinerary was to include a few days at Tambo before travelling directly to Iona Station near Hughenden.

The team consisted of experienced volunteers Carman Drake, Mary McCabe, Shirley Hopkins travelling with me in one vehicle and new volunteers, but experienced bushies, John Rideout and Barbara Howard in a second vehicle. John and Barbara left a few days earlier. The second vehicle departed on the 28 August.

We left Rockhampton and travelled via Emerald to Springsure. From there we followed the Dawson Development Road up the Nogoa River Valley and crossing the Great Dividing Range near Castlevale to reach Tambo for the night. John and Barbara were waiting for us there. The following day we travelled together about 40km south to Stirling Downs – our first study location in the headwaters of the Ward River.

The Ward River flows south to join the Warrego River which, in turn, flows to the Darling River.

We spent a few days on Stirling Downs as well as a “flying” visit to the nearby Bayrick Station. This excursion was cut short by threatening rain and greasy black-soil tracks. Rain eventually delayed us a day at Stirling Downs, but this was spent profitably trudging through black-soil paddocks to the creeks in search of koalas. We were warmly received by property owners Jenny and Jim Skelton. They kindly allowed us to use their shearer’s quarters -providing us with a well equipped base for our field work, property maps and reports as well as a very tasty fruit cake.

A day behind schedule we travelled west through heavy rain to Blackall then north to Barcaldine and then under clear skies to Muttaburra on the Thomson River. Here we set up camp in time for a wet and windy storm. Roads remained open and next morning we travelled north through the Landsborough Creek catchment to Hughenden and on to Iona Station. We set up camp on the banks of Walker Creek in time for another very wet night.

Walker Creek flows west to Landsborough Creek which flows to the Thomson River. The Thomson flows via Cooper Creek to Lake Eyre.

Weather cleared during the following morning but left us with some heavy black clay to walk through for a day or so. We spent the next week working on the creeks and hills around the property before John and Barbara left on the 9th September. The second vehicle departed on the 10th September. It was good to see Bill and Rhonda Rogers and their family after a few years and we enjoyed their kind hospitality, excellent company and fine cooking during our stay.

We travelled to the township of Torrens Creek (in the headwaters of the Flinders River that drains to the Gulf of Carpentaria) and then south following Bullock and Torrens creeks before turning east and passing Lake Galilee and crossing the Great Dividing Range, for the second time, near Lou Lou Station. We camped by the roadside in silver leafed ironbark woodlands before descending into the Burdekin basin, crossing the Belyando River and on to Clermont on the eastern slopes of the Drummond Range. From here we travelled across the Fitzroy basin on the high quality sealed roads busy with industrial traffic. We arrived in Rockhampton late that afternoon on the 11th September.

The trip lasted 15 days and we covered 3025km – mainly on dirt roads and in high range 4wd. We crossed five of Australia’s major drainage basins (Fitzroy, Murray-Darling, Lake Eyre, Carpentaria and Burdekin basins) all supporting koala populations.

Finding koalas and hugging trees
On Stirling Downs Jenny Skelton gave us an orientation property tour and then guided us to a well preserved koala skeleton. We quickly found fresh signs of koalas but walked a lot of creek lines before finding one elusive and somewhat ginger koala (Carmen did the spotting above Mary’s head!). Managers Matt and Jenny Peters kindly allowed us a flying visit to Bayrick Station. This was a short but productive trip and within an hour Mary spotting a well camouflaged koala in the forest canopy.

At Iona Station Bill Rogers directed us to areas where he had most recently seen koalas. After many kilometres of creek-walking we found three koalas (two males, one female).

But it was not all fun. The team spent many hours measuring trees so that the koala habitat can be described meaningfully. While they did that I wandered amongst the trees counting the number with koala pellets beneath them and measuring their girth so that I can have a measure of koala activity within the different plant communities and see if there was any size pattern in the trees with koala pellets beneath them.

In summary we found five koalas, collected one skeleton, measured almost 1,500 trees and collected three dozen bags of koala pellets. We also became experts in distinguishing koala pellets from possum pellets and aging the koala pellets by colour, texture and smell. The koalas used mainly river red gum and coolabah but also gidgee, boree, napunyah (less frequently), and rarely narrow leafed ironbark.

Enjoying “the bush”
Hardly an appropriate heading when refereeing to the Mitchell grasslands. However, you cannot spend days looking on the ground for koala pellets, in the canopy for koalas or across the paddock for the best path without encountering the richness of the landscape. So Barbara and John collected bird lists for both localities; Mary admired attractive rocks that could fit well into her garden; Carmen looked greedily at rocks, timber and abandoned and rusty bits of metal in old property rubbish dumps that held potential for transformation to works of art. She did find a very little time for sketching and wate colours. And then there was the excitement of encountering unexpected fossils in the mudstone and sandstone of the ancient inland sea. The undulating grasslands, stream fringing forests, gidgee and boree woodlands and the spinifex and ironbark uplands all held their own appeal especially in the warm light of sunset and sunrise. Red and grey kangaroos, wallaroos, swamp wallabies, emus and bustards were abundant and added to the excitement of driving on rural roads.

Ongoing work
We have brought back a large amount of data and specimens that require analysis and interpretation. The tree measurements will be used to develop a description of the composition and structure of the koala habitats at each location. The koala pellets will be analysed to discover the species of tree eaten by the koalas. It will take some time to complete this work but we should have some results by the new year.

We now have a better understanding of where to find the koalas and some guess as to how far they move each night. So we are now planning our next campaign. More on that in the future.

Thanks to our supporters
Jenny and Jim Stirling, Matt and Jenny Peters and Bill and Rhonda Rogers kindly allowed us access to their land and facilities. Dave Akers from the Queensland Environmental Protection Agency went out of his way to facilitate property contacts for us.
The Harvard Travellers Club provided funding towards transport costs for this expedition. The Central Queensland Koala Volunteers provided field equipment and some travel costs. CQUniversity Australia provided administrative support as well as access to laboratory and computing facilities to be used soon. The support of the team participants in running the trip and providing resources is gratefully acknowledged.

References
Gordon, G., Brown, A. S. and Pulsford, P. (1988) A population crash during heatwave conditions in southwestern Queensland. Australian Journal of Ecology 13, 451 – 461.
Gordon, G., Hrinda, F. and Patterson, R. (2006) Decline in the distribution of the koala (Phascolarctos cinereus) in Queensland. Australian Zoologist 33(3) 345 – 358.
Munks, S. A., Corkrey, R. and Foley, W.J. (1996) Characteristics of arboreal marsupial habitat in the semi-arid woodlands of North Queensland. Wildlife Research 23, 185 – 195.
Sullivan, B. J., Baxter, G. S. and Lisle, A. T. (2003) Low-density koala (Phascolarctos cinereus) populations in the mulgalands of south-west Queensland. III. Broad-scale patterns of habitat use. Wildlife Research 30, 583 – 591.
Sullivan, B. J., Baxter, G. S., Lisle, A. T., Pahl, L. and Norris, W. M. (2004) Low-density koala (Phascolarctos cinereus) populations in the mulgalands of south-west Queensland. IV. Abundance and conservation status. Wildlife Research 31, 19 – 29.
Sullivan, B. J., Norris, W. M. and Baxter, G. S. (2003b) Low-density koala (Phascolarctos cinereus) populations in the mulgalands of south-west Queensland. II. Distribution and diet. Wildlife Research 30, 331 – 338.

Alistair Melzer
18 September 2008

 

 

This entry was posted on Thursday, September 18th, 2008 at 10:01 pm and is filed under Alistair Melzer. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.