A project undertaken at the School of Natural and Built Environments, University of South Australia by PhD student Helen Waudby and supervised by Sophie (Topa) Petit
The cracking clay soils that occur in the South Australian rangelands provide shelter for small native animals and support biodiversity. Between 2008 and 2011the biodiversity of these areas and the effect of cattle, at study sites on a station in the arid north of South Australia. We sought to understand the role of cracking clay soils by trapping small vertebrates and invertebrates, radio-tracking, shelter studies, and vegetation assessments. We also surveyed pastoralists living in these areas to understand management issues.
Figure 1. Rainfall was experienced during most field trips.
Figure 2. Gilgais fill with water after substantial rainfall events.
Figure 3. Installing drift fences for vertebrate trapping.
The field work yielded some interesting results and we were able to witness the “boom” in rodents that tends to occur several months after large rainfall events. Many vertebrate species were caught, including plains rats and other native rodents, dasyurids such as Giles’ planigale (Planigale gilesi), gibber dragons (Ctenophorus gibba) and Woomera sliders (Lerista elongata). Many invertebrates were collected as well; their identification is in progress. Shelter use by fat-tailed (Sminthopsis crassicaudata) and stripe-faced (S. macroura) dunnarts was examined in several months. Radio-tracked individuals used a variety of cracks and burrows as shelter. Data loggers also revealed some interesting insights into the sheltering role of cracks.
Figure 4. Gibber dragons were caught in warm months.
Figure 5. Fat-tailed dunnarts were among the most common species caught (photo by Matthew Gill).
Figure 6. We radio-tracked dunnarts to examine shelter use (photo by Alison Fairlamb).
Unusual rainfall patterns occurred during much of the field work and they no doubt influenced the research. We consider ourselves fortunate to have seen the arid zone during a rare “wet” period, even if the excess water made field work difficult at times. Helen Waudby completed her PhD and continues to publish her thesis chapters. We expect that this research will contribute to the knowledge available on the dynamics of small vertebrate populations in the arid zone and the characteristics of cracking clay ecosystems under La Niña weather conditions.