RPS drives new scientific approaches to koala population assessment

RPS ecology and spatial data specialists are adopting contemporary scientific techniques to detect and monitor koala populations in Australia’s eastern states.

In New South Wales, RPS Ecologist, Mark Aitkens, is using a combination of contemporary methods to detect and better understand local koala numbers (passive acoustic recordings, detection dogs, DNA analysis and foliar nutritional studies). In North Queensland, RPS Survey Manager, Neil Roberts, is testing how infra-red drone mapping can be used for koala monitoring, in partnership with Mark, and the Magnetic Island Koala Hospital. While the approaches are different, together they represent exciting opportunities for effective, low impact assessment.

Passive acoustic recordings: hearing koala calls

In the Hunter region, Mark and his team have been using sound monitoring equipment called ‘song meters’ to record koala vocalisations known as ‘bellowing’.

An approach based on hearing rather than seeing the animals, our ecologists deploy the song meters in a specific spatial array to detect habitat occupancy. Recent scientific research has shown that this method has detection rates that are three times greater than conventional industry-accepted methods (i.e. Search Area Technique or SAT method).

While the method is not new, recent research supporting its application is compelling. Mark is confident that this passive monitoring technique is superior to the more traditional methods (i.e. SAT method), as it is less resource-intensive, provides a greater probability of detection, and offers greater insight into the kinds of koala activity occurring within the investigation area (i.e. breeding).

Dog detection: finding koala scats and more

A collaboration between RPS and OWAD Environmental is bringing the benefits of dog detection to environmental assessment projects in NSW and Queensland. OWAD Environmental specialises in using dogs to locate threatened species like koala and difficult to find plants such as underground orchids.

RPS has utilised these services to comprehensively map koala activity across a 500ha site in the Hunter Valley that features varying terrain and vegetation cover. The survey was also used to obtain koala faecal pellets for DNA analysis, with the results helping to profile individual koala's biological traits including their sex, relatedness to each other and disease status (i.e. infection of chlamydia and koala retrovirus).

These insights provide valuable knowledge on population dynamics and may be used for population monitoring using the principles of ‘mark – recapture’ without the need to interfere with the animals.

Foliar nutrient studies: understanding koala habitat

RPS, in collaboration with The Nutritional Ecology Lab (Dr Kara Youngentob and Dr Karen Marsh) at the Australian National University, has quantified eucalypt foliage quality across a 500 ha site in the lower Hunter Valley to aid decisions in the management of habitat critical to the koala.

Despite considerable variation across landscapes, forage quality has been largely ignored in considerations of habitat quality and restoration due to the difficulty of completing landscape-scale assessments.

With proven methods now available to rapidly assess the quality of eucalypt forage across wide areas using near-infrared spectrophotometry, it is possible to undertake assessments of the nutritional quality of the trees used as seed sources for revegetation projects and the nutritional quality of the habitats that result.

In the study, available nitrogen was empirically measured from site sampling to create a model revealing areas of high- and low-value browse (the vegetation that animals feed on). Areas of high-value browse were preferentially considered for impact avoidance, while areas within low-value browse have been considered for inclusion in a ‘habitat enrichment’ program to improve the carrying capacity of the forest.

Infra-red drone monitoring: seeing koala heat signatures

In Townsville, Survey Manager and Unmanned Aerial Vehicle (UAV) Pilot, Neil Roberts has been working with Mark, Dr Bee and Mr Bee from the Magnetic Island Koala Hospital to map populations from the air.

Responding to the devastating fires that burned through huge amounts of land during the 2019/20 bushfire season, RPS has combined Mark’s ecological expertise with Neil’s passion for aerial surveying to help the hospital better understand where koala communities are located.

Using a DJI Matrice 600 PRO drone fitted with infra-red detection equipment, Neil has already completed two fly-over surveys to test how tracking koala heat signatures can allow them to be spotted easily in the trees over far larger areas than possible with traditional visual monitoring.

The strategy is proving effective, though Neil notes that in regions where the weather is hot, it is important to survey in the early morning to ensure hot ambient temperatures do not mask the koalas’ body heat.

‘With all of the devastation to native animal populations that we saw as a result of the 2019/20 bushfire season, having the ability to collect and interpret reliable ecological data is more important than ever,’ said RPS Executive General Manager – Place & Environment, Susan Farr.

‘Mark and Neil are pushing the boundaries of ecological monitoring methodology and testing out new techniques with our clients and community partners.

‘Seeing our environmental and spatial disciplines intersect is really exciting. I’m so proud that my team is out there leading the charge on data-driven environmental investigation and management,’ she said.

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