The April desert trip had two parts as a first vehicle left Sydney on 31 March and the other three vehicles departed on 8 April.
The first morning was spent opening grids for trapping and setting up Stephanie’s GUD (‘Giving Up Density’) experiment. The latter experiment aims to look at the interaction of predation risk with food choice by offering a variety of seeds of varying palatability in different predation contexts (trays in the open and near cover, and across multiple seasons). Peanuts are offered initially, to get the rodents accustomed to the food supply. Stephanie anticipated many peanut takes by the rodents given that food availability is likely to be low during the current dry period in the desert.
Every morning before the sun came up Stephanie would check the GUD plates for foot prints, count peanuts or collect petri dishes for weighing. Overall, in this experiment more seed was eaten from the open areas rather than the closed. Predator numbers seemed low (evident from the scarce predator prints and scats), it may be that rodents felt it was ‘safe’ in the open areas. As shown on previous trips, the rodents had a preference for Triodia and Grevillea seeds over Trachymene and Goodenia. During the first stage of the experiment while peanuts were offered, the prints left by the tray visitors were obscured by the rain on one night, but overall the experiment ran smoothly.
The trip was very busy with Eveline, Stephanie, Sonny and Chris all running experiments, together with the regular trapping regime. Throughout the trip Chris, Mardi and Sonny checked traps and processed the few captures, then closed the grids after three nights and opened new grids to start the process again.
Chris conducted his own experiments during the trip using GUD dishes at the predator proof tunnel, control ‘sham’ tunnel and control grids. Chris used meal worms hoping to tempt the dunnarts, which ate quite a few, but many non-target species also found the dishes – such as reptiles and ravens! Chris had to get up pretty early to beat the ravens. While it seemed like the local rodents were being spoiled with cashews provided in GUD dishes, it seems that they didn’t appreciate the offerings, as not many were taken.
Eveline spent the trip creating enclosures for her next experiment and conducting a pilot trial. This involved building an enclosure using mesh and attaching rubber on the bottom to stop the dragons escaping the enclosures. Eveline and Sonny also cleared every speck of vegetation in the enclosures so that she could manipulate vegetation cover (this involved a lot of digging)! With the enclosures set up, she caught a few military dragons (Ctenophorus isolepis) and released them in the enclosures. She then set up kites in the shape of hovering raptors to provide an artificial ‘predation risk’. The dragons appeared to recognise the kites as a threat, so this seems like a successful method!
At night Sonny conducted an experiment using dunnarts and rodents in an ‘interview chamber’. This tested the feeding choices of dunnarts using boxes with different numbers of mealworms in each and seeing which the dunnarts ate from.
We ended up leaving a few days earlier than planned but by the time everyone had finished their experiments and work, we were ready to go home.
The weather in western Queensland couldn’t quite make up its mind when our trip rolled around. The swelteringly hot summer temperatures had persisted through March and into the start of April, followed by a ‘cold snap’ that hit right around the time our group joined the first crew at Main Camp on the 10th. Daytime temperatures then slowly climbed back up to the high-30s over the next few days. It was a pretty big surprise then, when the first drops of rain fell one night. Those of us that roused ourselves and put tents up were glad we did though, as the few drops turned into a pretty constant rain for a good few hours. Others slept blissfully in their swags but learnt a lesson about not using plastic tarps underneath swags as it encourages pooling of water and seepage. When the rain passed, it stayed chilly for a couple of days, warming up slightly before plunging into another cold spell before we left – the 7° C nights felt well and truly like winter.
Whether it was the weather or some other mysterious factor, we had a several snake sightings at the start of this trip, which is highly unusual. Chris encountered a brown snake (Pseudonaja sp.) out on a Main Camp grid, and a couple more were spotted hanging around the caravan. Fortunately the snake near the water station disappeared on its own without incident. Dave saw a Yellow-Faced Whip Snake (Demansia psammophis) at South Site, then another one out on the road near Plum Pudding. Finally JP and Eveline came across a Mulga (Pseudechis australis) on the track to the Ethabuka homestead.
For the first few days of our trip, we all stayed at Main Camp while conducting trapping and veg plot surveys at Shitty Site, South Site, Way Site and Carlo. Camp felt pretty crowded with 20 bodies (Figure 5) – the only consolation being that with so much coming and going it seemed that dinner time was the one occasion when everyone was present at once.
On the upside, the large team was highly beneficial when it came to the field work. In addition to the routine surveys we also gathered another year of data (biomass and plant composition) for Glenda’s NutNet experiments at Main Camp and South Site. We still enjoy the process of scattering the nutrients into the treatments and it is fondly referred to as ‘feeding the chooks’.
Last year, fifteen 1 ha Ausplots (see http://www.tern.org.au/AusPlots-pg26979.html) were established at our study sites as part of a national rangelands survey, 5 around Main Camp, 5 at Field River and 5 more up north on Cravens Peak. The full survey is done with standardized protocols for surveying vegetation structure and composition and soils. This year, as part of Glenda’s project to remeasure the AusPlots for the next five years, we re-surveyed them, focusing on the measures that are expected to change most over time; point-intercept records of vegetation structure, plant composition, basal areas measurements and the standard photo panoramas. We also deployed a remote camera at the centre of each plot.
After Chris’s group departed to head back to Sydney, the rest of the crew split into three groups. Tom and Emma stayed at Main Camp whilst Dave took JP, Rhiannon and Kristian out to Tobermorey, and everyone else headed out to Field River.
Tom and Emma had a difficult task – to try to trap some cats and attach ARGOS tracking collars. The evidence of cats and foxes has been very sparse in recent months – probably reflecting low prey numbers. “Trapper Tom” put out every functioning soft-jaw trap that he could get his hands on, with a variety of stinky lures to tempt any cats that might be in the area. Every morning the traps were checked, and every afternoon fresh lures were applied. After over a week at Main Camp, things were looking pretty dismal – there weren’t any cat tracks even close to the traps. The only animal trapped was a young dingo.
It’s always nice getting out to Tobermorey and seeing how the Northern Territory is faring. The biggest change from recent trips was the amount of green. Some areas had evidently copped some significant rainfall, resulting in some lush grass growth in some areas. The most extreme example was right near the Tobermorey West weather station where the ground was blanketed in still green grass and a few flowers – a quick look at the data revealed that a dump of approximately 70mm had fallen on a single day in March. Evidence suggested that this was a fairly isolated storm, as only 14 km away our eastern weather station didn’t get any of it. Tobermorey camp must have also got some good rain, and the normally dusty ground was carpeted in thick grass, sedge and nardoo ferns.
Small mammal numbers at Tobermorey reflected the good conditions, with quite a few Sandy Inland Mice (Pseudomys hermannsburgensis) several Spinifex Hopping Mice (Notomys alexis), and even a Desert Mouse (Pseudomys desertor) turning up. The rain hit during this trapping session, so we were treated to the appearance of some desert frogs – the Desert Spadefoot (Notaden nichollsi) which we got in the traps, and the Trilling frog (Neobatrachus sudellae) which we spotted active at night in the swale near camp.
Two vehicles headed by Glenda, Aaron and Bobby made the two-hour journey over 80+ dunes to the camp at Field River. Two grids at Field River North and two grids at Field River South were opened with relatively high capture rates of mammals (including several mulgara (Dasycercus bythyii) and reptiles compared with other sites during the trip. Like the crew at Tobermorey, the 10mm of recorded rainfall during the trapping session also produced some desert frogs in the traps. Four “Boom and Bust’ veg plots were also sampled, the data indicated flowering in some of the dune top species probably due to some localised rainfall. Another goal for the Field River crew was to re-survey the five Ausplot grids that had been established in April 2014. The volunteer crew handled the challenge of the Ausplots with aplomb; they overcame the impaired line-of-sight in the mallee and the coolabahs using the tall poles and pegs with attached flagging tape like veteran surveyors (Figure 2). However, due to the rainfall on previous days only 4 of the 5 Ausplot grids at Field River were surveyed completely with the fifth (QDASSD0010) given an abbreviated survey.
With the second trapping session of our trip completed, it was time to move camp again. Dave’s group relocated to Kunnamuka swamp and opened up four grids in the area. Tom and Emma drove north and set up their soft-jaw traps again around Ocean Bore. The Field River crew stayed another day or two to finish sampling Ausplot grids before also heading to Ocean Bore. Dave’s crew pre-empted their arrival by opening trapping grids near Ocean Bore and out at Plum Pudding – also an opportunity to visit the bore for a quick wash and a group reunion over ‘Mediterranean’ cuisine, along with some extra protein in the form of bush tucker.
Earlier, when leaving the swamp on the way to Ocean Bore, Dave remarked that it might be a good day for Thorny Devils (Moloch horridus) on the road. Only a couple of kilometres down the track his prediction came good, with first one then another of these spectacular little beasts. Interestingly, the first individual had apparently been ‘chomped’ on its spiny false head by a would-be predator.
The predator-trapping team was having some success, though not with the target species – still no cats! Two foxes, however, had been successfully trapped around Ocean Bore, and given the dearth of cats, the decision was made to collar the foxes instead. The third collar was eventually deployed also, when the final trap checked on the final day yielded another fox. We’re now able to download fox location data calculated from messages sent by the collars to ARGOS satellites!
Pitfall trapping at Kunnamuka Swamp was fairly unexceptional; the biggest highlights were probably a couple of Mulgaras (Dasycercus blythii). Across sites this trip, the species seemed to turn up in slightly better numbers than in the last couple of years.
The final job before heading off Sydney-bound was setting up a couple of Droughtnet sites (see http://wp.natsci.colostate.edu/droughtnet/). DroughtNet is another global distributed experiment to determine how drought will influence plant productivity and diversity. We chose to install two sites on Ethabuka, near the Main Camp North weather station where we had access to a burnt area and an unburnt one on either side of the road. Each site consisted of six small plots which as part of the baseline year only required marking out, surveying and sampling biomass. Next year the infrastructure for the treatments will be imposed, which will involve building shelters to impose drought, and irrigating to simulate elevated rainfalls, and the obligatory controls.