Conservation of Western Ringtail Possums in Margaret River: What the Latest Data Actually Shows

For World Wildlife Day, we explore in this blog what the latest data on Margaret River’s Western Ringtail Possums actually shows and how it helps reinforce our conservation priorities at Passel Estate.

In the Margaret River region, conversations about the Western Ringtail Possum have often centred on decline. Earlier reports suggested very low remaining numbers. Those figures shaped funding priorities, habitat protection decisions and public messaging across the South West.  They also galvanised Passel Estate owners, Wendy and Barry Stimpson, into focusing their conservation projects at the estate around rehabilitating Western Ringtail Possums on the property.

Recent research from Murdoch University has introduced updated data that changes how scale of the population is understood, even if it does not change the conservation status of the species.

The Western Ringtail Possum remains listed as critically endangered. That classification has not shifted. What has shifted is the estimated number of individuals within surveyed areas, which by itself is encouraging.

A revised estimate across the South West

A large-scale field survey completed in 2025 expanded the geographic footprint of previous studies. Rather than relying primarily on localised counts, researchers applied consistent survey methods across 41 sites covering a substantial portion of the possum’s known range.

More than 1,200 kilometres of transects were walked as part of the work.

When analysed, the results suggested approximately 21,800 Western Ringtail Possums within the surveyed footprint. Earlier, widely cited figures had placed the number far lower.

This difference does not indicate a sudden population increase. It reflects broader survey coverage and improved consistency in data collection.

Lead researcher Roy Teale addressed this distinction directly.

“Higher numbers don’t mean the species is safe.”

He also stated:

“With climate change driving more frequent and intense heatwaves, our latest findings show new risks emerging that could still threaten the species’ long-term survival.”

The revised estimate provides a clearer baseline. It does not remove the threats associated with habitat fragmentation, fire risk or climate pressure.

Why earlier numbers were different

Population estimates depend heavily on sampling design. When survey coverage is uneven, assumptions must be made about areas that have not been measured.

The recent survey reduced that uncertainty by expanding spatial coverage and standardising field effort. That methodological shift is significant. It increases confidence in understanding where possums persist and in what densities.

It also highlights the importance of ongoing monitoring. A single estimate, whether high or low, does not define long-term trajectory.

Heat stress remains a concern

Alongside the population survey, Murdoch researchers examined how extreme heat affects possum behaviour.

During the summer of 2024 to 2025, ten possums were monitored using lightweight GPS collars and motion-sensitive cameras. Several days exceeded 40 degrees Celsius.

Researcher Harry Moore described changes observed during hot conditions.

“What really stood out was that the biggest drop in activity happened early in the evening, when western ringtail possums usually do most of their feeding.”

Reduced feeding during peak heat periods can affect body condition and reproduction. One monitored possum died during a heatwave. Others displayed signs of heat stress including panting and paw licking.

The behavioural findings suggest that even if overall numbers are higher than previously thought, climatic pressures remain a real constraint on long-term stability.

What this means for our conservation projects

For properties across Margaret River that retain native vegetation, the updated data reinforces the value of habitat continuity across mixed land use landscapes.

Passel Estate maintains large areas of protected bushland on site and has supported wildlife conservation initiatives over many years, including habitat retention and collaboration with wildlife carers for the soft release of Western Ringtail Possums back into the area.

The Murdoch survey did not evaluate individual properties. It assessed distribution patterns across the broader region. However, the findings imply that remnant vegetation on private land forms part of a larger ecological network supporting the species.

The updated estimate does not imply that conservation work is complete. Nor does it suggest that earlier figures were incorrect in intent. It demonstrates that broader and more systematic measurement produces a different understanding of scale.

For landholders, researchers and conservation groups, that distinction matters. Accurate baselines support more precise planning. Habitat protection remains central to wildlife conservation regardless of population estimates.

Further details about the study are available through Murdoch University:  Western ringtail possums are feeling the heat