Cycles of weeds & fat budgies

Before managing Naree Reserve for us in NW NSW, Dave Akers worked in the channel country west of Longreach. In 2018, Dave and Sue returned to that big sky country as Bush Heritage volunteers to undertake buffel grass surveys on Pullen Pullen Reserve which they completed during a second visit in March this year.

In 1994, a colleague and I camped at the base of a mesa on Brighton Downs Station in Queensland’s Channel Country. Working for the Department of Natural Resources, we were en route to survey weed infestations along Spring Creek on the western floodplain of the Diamantina River. Fast forward to 2018 – Sue and I were in a side by side (SXS) Polaris four-wheeler skirting around the same mesa on the margin of the Diamantina floodplain.

As Sue eased the Polaris over a stony ridge, I pointed out our campsite from 23 years earlier. Again, the mission was a weed survey – this time on the Bush Heritage Australia property Pullen Pullen. We were taking time out, having recently completed a five-year stint managing Bush Heritage properties in north-west NSW, and had volunteered to do the weed survey project. The survey data would contribute to management planning for the new reserve. 

Originally part of the 420,000ha Brighton Downs holding, Pullen Pullen was purchased in 2016 from the Britten family as part of a national strategy to conserve the endangered Night Parrot (Pezoporus occidentalis). Pullen Pullen is the name given to the night parrot by the traditional owners for the area, the Maiawali people. The mysterious little bird is also referred to by the unglamorous title of 'fat budgie'.

Pullen Pullen is only 50km from Old Cork Station – immortalised by Redgum in their 1983 ballad 'The Diamantina Drover'.  Mesas and stony outwash areas of the Mayne and Nisbet ranges dominate the eastern part of the property with extensive areas of spinifex (Triodia spp.) grassland and mulga (Acacia aneura) woodlands.

The tall spinifex hummocks are considered critical habitat for the Night Parrot. The drainage lines, which are rough and steep-sided, flow westward onto the Diamantina River floodplain where they become shallower and more divided. On the alluvial floodplain soils the dominant vegetation becomes gidgee (Acacia cambagei) riparian woodland with adjacent Mitchell grass (Astrebla spp.) plains.

After settling into the Brighton Downs ringers’ quarters, we spent the first day in the Polaris four wheeler familiarising ourselves with the property boundaries, access tracks and drainage lines, as these would determine our strategy for the survey.

Satellite imagery on a GPS-enabled tablet made locating our position on the property simple and accurate. Buffel grass (Pennisetum ciliare) was our main target, as this invasive grass could potentially degrade key habitat areas for the Night Parrot. Other invasive exotics likely to occur in the area were the thorny shrub species Prickly Acacia (Acacia nilotica), Mesquite (Prosopis spp.) and Parkinsonia (Parkinsonia aculeata).

The actual survey work would be carried out on a motorcycle as it was simply not possible to get a four wheel drive vehicle or even the four wheeler into the rough drainage lines and dense riparian areas that needed to be surveyed in detail, and the distances are such that walking was not a practical alternative.

Even a drone is not a viable option due to the dense canopy cover in many areas, so once we'd determined the methodology Sue worked in a support/backup role from the quarters.

All drainage lines and flood-out areas, and places of disturbance such as tracks, fence lines, opal mining sites, stockyards and dams were surveyed. The locations of weed infestations were recorded as GPS waypoints and further detail entered into hard copy datasheets.

The track log was also recorded so that the areas surveyed could be clearly defined. As well as the GPS and tablet, a SPOT tracker was carried which sent a regular GPS location to Bush Heritage managers, and a satellite phone was used for emergency contact. A data sheet holder, first aid/snake bite kit, hydration pack with 4 litres of water, enough food to maintain energy levels for a day and a small tool kit were also on board.

Surveying in this manner is both physically and mentally demanding as the motorcycle operator is scanning continually for target species while finding a path through, over or around obstacles, and keeping the whole show upright.

The motor tends to get very hot, as does the operator, so it's important to have hourly breaks or concentration will start to fade and the required work standard will not be maintained. That's also when an accident is likely to occur.

Eight days were spent surveying, covering over 450 kilometres. Buffel grass was the only weed species recorded, which is a credit to the previous property owners and managers. About 200 infestations were recorded, although many of these were small, isolated and easily controllable. The only incident was a single puncture which was remarkable given the terrain covered.