By Dr Holly Sitters, Senior Wildlife Ecologist; Dr Liana Joseph, National Science Manager; Dr John Kanowski, Chief Science Officer
The Ecohealth Monitoring Program underpins AWC’s effective model of science-led conservation management. The program aims to address fundamental questions relevant to the achievement of AWC’s mission, such as ‘Are species persisting?’, ‘Are habitats being conserved?’ and ‘Are threats being managed adequately?’
Each year, an immense effort by AWC staff, interns and volunteers goes into monitoring biodiversity on sanctuaries and partnership areas nationwide. In 2022, the Ecohealth program comprised over 280,000 trap nights (camera and live trapping) and almost 2,000 bird surveys, making it Australia’s most extensive field monitoring program. In July, AWC released the 2022 Ecohealth reports and scorecards, marking the third consecutive year of publication.
AWC’s Ecohealth program uses established, targeted techniques to collect detailed information on species of high conservation value, such as threatened and reintroduced species. It is crucial, however, that we also monitor and evaluate conservation outcomes for the broader species assemblages.
A key issue is that changes in the abundance or distribution of a species reflect a combination of responses to threats, to management and to a range of natural phenomena, such as fluctuations in weather patterns. This is particularly evident in Australian ecosystems, where species increase and decline in response to pulses of rainfall and drought; such boom-and-bust dynamics are a natural feature of arid, semi-arid and sub-tropical environments. Deciphering which declines are of concern, because they reflect a threatening process, from the declines that occur naturally is a key challenge in evaluating monitoring data. If we can disentangle these factors, the data can provide early warning of declines that are of conservation concern, enabling timely action to mitigate threats and promote the persistence of species.
AWC’s National Science Team has been working on ways to address these issues, utilising long-term datasets collected on AWC sanctuaries.
Long-term monitoring at Kalamurina Wildlife Sanctuary
AWC has 15 years of Ecohealth monitoring data on birds, mammals, reptiles and frogs from Kalamurina, a vast desert landscape adjacent to Kati Thanda–Lake Eyre National Park and Munga-Thirri–Simpson Desert Reserve in South Australia (together protecting an area larger than Tasmania). Analysis has shown that several species were thriving in 2022, after persisting at very low densities during drought conditions in previous years. In 2022, Crest-tailed Mulgara abundance was much higher than in most previous years, the Mayaroo (Long-haired Rat) was caught for the first time in 10 years, while a dozen Dusky Hopping-mice were caught – by far the most since surveys began. At the same time, the activity of feral cats and foxes on Kalamurina remained low. Based on this evidence, the increased abundance of mammals in 2022 is likely a reflection of AWC land management, prevailing wet conditions and low densities of introduced predators.
Long-term monitoring at Buckaringa Wildlife Sanctuary
At Buckaringa in semi-arid South Australia, AWC has 12 years of Ecohealth monitoring data. This long-term dataset was used to test the application of two methods for evaluating changes in abundance of 15 bird species (the threatened Southern Whiteface and 14 common species) and the threatened Yellow-footed Rock-wallaby. We first examined whether abundance was correlated with rainfall over the baseline period (roughly the first 10 years of data). If it was, we compared the 2022 abundance results with predicted values based on a rainfall model derived from the baseline data, to determine whether abundance was higher, lower, or similar to expectations given recent rainfall. For species where abundance was not well correlated with rainfall, we compared 2022 results with the range of values observed in the baseline data.
Abundance of the Yellow-footed Rock-wallaby was strongly associated with rainfall; it declined over the 2018–19 drought but has since stabilised, indicating that higher rainfall since 2020 has benefitted the population. However, abundance in 2022 was at the lower end of the range predicted from rainfall, implying the population has been suppressed by threatening processes. Survey results showed that foxes and feral cats have been maintained at low to moderate densities, but that the Euro (Common Wallaroo) population has increased. Euros may compete with rock-wallabies for food, particularly during dry periods when resources are scarce. AWC will continue to carefully monitor and manage threats that may affect the sanctuary’s rock-wallabies.
The Southern Whiteface was among seven bird species that returned a ‘within baseline’ evaluation in 2022. The Southern Whiteface is generally considered sedentary but may move outside its normal range during drought; it was not recorded on Buckaringa in the 2018–19 drought but was abundant in 2022. In contrast, the White-winged Fairywren and Rufous Whistler returned a ‘below baseline’ score and several other species were not detected at all in 2022. Of particular concern are two species, the Purple-backed Fairywren and Inland Thornbill, which have both declined at Buckaringa since 2009. While the Purple-backed Fairywren is considered stable across its range, the Inland Thornbill is among many species of woodland birds that are declining regionally.
Cues for conservation action
Both the Kalamurina and Buckaringa long-term-monitoring datasets are a testament to the expertise and commitment of Senior Wildlife Ecologist, Keith Bellchambers, who has led field data collection and reporting at both sanctuaries since 2008. A network of AWC scientists, like Keith, and volunteers are working tirelessly to ensure we are equipped with the knowledge required to take prompt action for the benefit of wildlife. These methods of evaluation will continue to be refined using other datasets, before being implemented across the AWC estate.
Many threatened species were once common. Long-term monitoring is helping us to understand why declines happen. Being able to identify early warning signals of decline will provide opportunities for rapid conservation action to prevent more species from becoming imperilled or extinct.
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