The greater bilby (Macrotis lagotis) is one of Australia’s most iconic yet at-risk animals — and the last surviving bilby species. Once found across 70% of Australia, its range has contracted by more than 80% since European colonisation.
Today, these nocturnal marsupials, still culturally significant to many Indigenous peoples, are restricted to remote deserts. They face an ongoing threat of extinction.
Local elders, Indigenous rangers and scientists hold valuable knowledge about bilby populations, the threats they face, and strategies needed to sustain them into the future.
Our new study, published today in Conservation Science and Practice, reveals how collaboration between scientists and Indigenous land managers can help yield new and vital information.
In the field, we used two methods – one based on Warlpiri knowledge and one based on standard scientific protocols – to locate bilbies and collect scat (poo) samples in the North Tanami Indigenous Protected Area in the Northern Territory.
By drawing on Warlpiri tracking expertise and Western scientific methods, we uncovered crucial information on bilby populations that could help conserve these rare creatures.
Understanding bilby numbers is important – but hard
Bilbies turn over tonnes of soil each year, helping to improve soil health, help seeds germinate and enhance water infiltration. Their deep, complex burrows also provide shelter for other species.
They’re crucial to the health of desert ecosystems; protecting bilbies means protecting the web of life they support.
To do this, we need to know more about:
how many bilbies there are
how they respond to land management techniques such as planned burning
how they respond to threats such as feral predators.
Yet, bilbies are notoriously difficult to monitor directly via live capture. They’re nocturnal, shy and solitary. And they inhabit vast landscapes, making it very hard to estimate population numbers.
Bilby tracks North Tanami (pen for scale).Hayley Geyle/Author Provided
Luckily, the tracks, diggings and scats bilbies leave behind provide ample clues. DNA from scat (if it can be found) can be used to estimate how many bilbies are present in a particular area.
Systematic ecological surveys, often used to monitor wildlife, can be rigid and expensive, especially in remote regions.
We need flexible methods that align with local knowledge and the practical realities of monitoring bilbies on Country.
A new approach to monitor and manage bilbies
We tested two methods of locating bilby scat for DNA analysis.
The first was systematic sampling. This is a standard scientific approach where fixed lengths of land were walked multiple times to collect scat.
This ensures sampling effort is even over the search area and comparable across sites. However, like most species, bilby distribution is patchy, and this approach can lead to researchers missing important signs.
The second method was targeted sampling, guided by Warlpiri knowledge, to search in areas most likely to yield results.
This allowed the search team to focus on areas where bilbies were active or predicted to be active based on knowledge of their habits and food sources.
Altogether, we collected more than 1,000 scat samples. In the lab, we extracted DNA from these samples to identify individual bilbies. These data, combined with the location of samples, allowed us to estimate the size of the bilby population.
We then compared estimates that would have been derived if we had only done systematic or targeted sampling, or both, to assess their strengths and limitations for monitoring bilby populations.
The deep, complex burrows of bilbies also provide shelter for other species.Kelly Dixon/Author provided
What we found
We identified 20 bilbies from the scats collected during systematic surveys and 26 – six more – from targeted surveys. At least 16 individual bilbies were detected by both methods. In total, we confirmed 32 unique bilbies in the study area.
When it came to population estimates – which consider how many repeat captures occur and where – combining data from both types of surveys produced the most accurate estimates with the least effort.
Targeted sampling tended to overestimate population size because it focused on areas of high activity. Systematic sampling was more precise but required greater effort.
Combining both approaches provided the most reliable estimates while saving time.
In the lab, we extracted DNA from bilby scat samples to identify individual bilbies.Hayley Geyle/Author provided
What this means for conservation
Our research highlights how collaboration that includes different ways of knowing can improve conservation.
By adapting standard on-ground survey techniques to include Warlpiri methods for tracking bilbies, we produced better data and supported local capacity for bilby monitoring.
Conservation programs often rely on standardised ecological monitoring protocols – in other words, doing things much the same way no matter where you’re working.
While these protocols provide consistency, they are rigid and don’t always yield the best results. They also fail to incorporate local knowledge crucial for managing species like the bilby.
Our approach shows how integrating diverse ways of working can deliver more inclusive and effective outcomes, without compromising data reliability.
Their future depends on collaborative efforts that draw on scientific and Indigenous and local knowledges.
This study provides an example of how such partnerships can work – not just for bilbies, but for other species and ecosystems.
As Australia confronts biodiversity loss, this research underscores the importance of listening to those who know Country best.
By valuing and respecting local expertise, we can build a stronger future for bilbies and the landscapes that are their home.
Hayley Geyle is employed by Territory NRM, who receives funding for threatened species projects from the Australian government through the Natural Heritage Trust. She also works on the Digital Women Ranger project. She is affiliated with Territory NRM and the Northern Institute (Charles Darwin University).
Cathy Robinson is employed at CSIRO and is Group Leader in the Agriculture and Food Sustainability Program and Research lead for the Digital Women Ranger Program which is supported by the Telstra Foundation. Cathy is also an Adjunct Professor at Charles Darwin University, Chair of IUCN Australian Expert Advisory Panel for the Green List, and Executive Advisor for the Liveris Academy for Innovation and Leadership at the University of Queensland.
Christine Schlesinger does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
Helen Wilson does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
After trespassers vandalised Koonalda Cave on the Nullarbor Plain a round-the-clock surveillance system was installed to help protect the nationally significant heritage site.
If you go walking in the wild, you might expect that what you’re seeing is natural. All around you are trees, shrubs and grasses growing in their natural habitat.
But there’s something here that doesn’t add up. Across the world, there are large areas of habitat which would suit native plant species just fine. But very often, they’re simply absent.
Our new research gauges the scale of this problem, known as “dark diversity”. Our international team of 200 scientists examined plant species in thousands of sites worldwide.
What we found was startling. In regions heavily affected by our activities, only about 20% of native plant species able to live there were actually present. But even in areas with very little human interference, ecosystems only contained about 33% of viable plant species.
Why so few species in wilder areas? Our impact. Pollution can spread far from the original source, while conversion of habitat to farms, logging and human-caused fires have ripple effects too.
Conspicuous by their absence
Our activities have become a planet-shaping force, from changing the climate through our emissions to farming 44% of all habitable land. As our footprint has expanded, other species have been pushed to extinction. The rates of species loss are unprecedented in recorded history.
When we think about biodiversity loss, we might think of a once-common animal species losing numbers and range as farms, cities and feral predators expand. But we are also losing species from within protected areas and national parks.
To date, the accelerating loss of species has been largely observed at large scale, such as states or even whole countries. Almost 600 plant species have gone extinct since 1750 – and this is likely a major underestimate. Extinction hotspots include Hawaii (79 species) and South Africa’s unique fynbos scrublands (37 species).
But tracking the fate of our species has been difficult to do at a local scale, such as within a national park or nature reserve.
Similarly, when scientists do traditional biodiversity surveys, we count the species previously recorded in an area and look for changes. But we haven’t tended to consider the species that could grow there – but don’t.
Many plants have been declining so rapidly they are now threatened with extinction.
What did we do?
To get a better gauge of biodiversity losses at smaller scale, we worked alongside scientists from the international research network DarkDivNet to examine almost 5,500 sites across 119 regions worldwide. This huge body of fieldwork took years and required navigating global challenges such as COVID-19 and political and economic instability.
At each 100 square metre site, our team sampled all plant species present against the species found in the surrounding region. We defined regions as areas of approximately 300 square kilometres with similar environmental conditions.
Just because a species can grow somewhere doesn’t mean it would. To make sure we were recording which species were genuinely missing, we looked at how often each absent species was found growing alongside the species growing at our chosen sites at other sampled sites in the region. This helped us detect species well-suited to a habitat but missing from it.
We then cross-matched data on these missing species against how big the local human impact was by using the Human Footprint Index, which measures population density, land use and infrastructure.
Of the eight components of this index, six had a clear influence on how many plant species were missing: human population density, electric infrastructure, railways, roads, built environments and croplands. Another component, navigable waterways, did not have a clear influence.
Interestingly, the final component – pastures kept by graziers – was not linked to fewer plant species. This could be because semi-natural grasslands are used as pasture in areas such as Central Asia, Africa’s Sahel region and Argentina. Here, long-term moderate human influence can actually maintain highly diverse and well-functioning ecosystems through practices such as grazing livestock, cultural burning and hay making.
Semi-natural pastures preserve many different plant species. Pictured: the Hulunbuir grasslands in Inner Mongolia, China.Dashu Xinganling/Shutterstock
Overall, though, the link between greater human presence and fewer plant species was very clear. Seemingly pristine ecosystems hundreds of kilometres from direct disturbance had been affected.
These effects can come from many causes. For instance, poaching and logging often take place far from human settlements. Poaching an animal species might mean a plant species loses a key pollinator or way to disperse its seeds in the animal’s dung. Over time, disruptions to the web of relationships in the natural world can erode ecosystems and result in fewer plant species. Poachers and illegal loggers also cut “ghost roads” into pristine areas.
Other causes include fires started by humans, which can threaten national parks and other safe havens. Pollution can travel and settle hundreds of kilometres from its source, affecting ecosystems.
Our far-reaching influence can also hinder the return of plant species, even in protected areas. As humans expand their activities, they often carve up natural areas into fragments cut off from each other. This can isolate plant populations. Similarly, the loss of seed-spreading animals can stop plants from recolonising former habitat.
What does this mean?
Biodiversity loss is not just about species going extinct. It’s about ecosystems quietly losing their richness, resilience and functions.
Protecting land is not enough. The damage we can do can reach deep into conservation areas.
Was there good news? Yes. In regions where at least a third of the landscape had minimal human disturbance, there was less of this hidden biodiversity loss.
As we work to conserve nature, our work points to a need not just to preserve what’s left but to bring back what’s missing. Now we know what species are missing in an area but still present regionally, we can begin that work.
The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.
Australia is a place of great natural beauty, home to many species found nowhere else on Earth. But it’s also particularly vulnerable to introduced animals, diseases and weeds. Habitat destruction, pollution and climate change make matters worse. To conserve what’s special, we need far greater care.
Unfortunately, successive federal governments have failed to protect nature. Australia now has more than 2,000 threatened species and “ecological communities” – groups of native species that live together and interact. This threatened list is growing at an alarming rate.
The Albanese government came to power in 2022 promising to reform the nation’s nature laws, following a scathing review of the laws. But it has failed to do so.
But scientific evidence suggests much more is required to protect Australia’s natural wonders.
Fighting invaders
Labor has made a welcome commitment of more than A$100 million to counter “highly pathogenic avian influenza”. This virulent strain of bird flu is likely to kill millions of native birds and other wildlife.
The government also provided much-needed funding for a network of safe havens for threatened mammals. These safe-havens exclude cats, foxes and other invasive species.
But much more needs to be done. Funding is urgently needed to eradicate red imported fire ants, before eradication becomes impossible. Other election commitments to look for include:
national coordination and leadership to stop the indiscriminate use of poisons that can spread through ecosystems and food-chains, killing non-target animals such as owls, quolls, Tasmanian devils, reptiles and frogs.
Stopping land clearing and habitat destruction
The states are largely responsible for controlling land clearing. But when land clearing affects “matters of national environmental significance” such as a nationally listed threatened species or ecological community, it becomes a federal matter.
Such proposals are supposed to be referred to the federal environment minister for assessment under the Environment Protection and Biodiversity Conservation (EPBC) Act.
Only about 1.5% of the hundreds of thousands of hectares of land cleared in Australia every year is fully assessed under the EPBC Act.
This means our threatened species and ecological communities are suffering a “death by a thousand cuts”.
How do we fix this? A starting point is to introduce “national environmental standards” of the kind envisaged in the 2020 review of the EPBC Act by Professor Graeme Samuel.
Habitat destruction at Lee Point, Darwin.Martine Maron
Protecting threatened species
For Australia to turn around its extinction crisis, prospective elected representatives and governments must firmly commit to the following actions.
Stronger environmental law and enforcement is essential for tackling biodiveristy decline and extinction. This should include what’s known as a “climate trigger”, which means any proposal likely to produce a significant amount of greenhouse gases would have to be assessed under the EPBC Act.
This is necessary because climate change is among the greatest threats to biodiversity. But the federal environment minister is currently not legally bound to consider – or authorised to refuse – project proposals based on their greenhouse gas emissions. In an attempt to pass the EPBC reforms in the Senate last year, the Greens agreed to postpone their demand for a climate trigger.
A large increase in environmental spending – to at least 1% of the federal budget – is vital. It would ensure sufficient support for conservation progress and meeting legal requirements of the EPBC Act, including listing threatened species and designing and implementing recovery plans when required.
Show nature the money!
Neither major party has committed to substantial increases in environmental spending in line with what experts suggest is urgently needed.
Without such increased investment Australia’s conservation record will almost certainly continue to deteriorate. The loss of nature hurts us all. For example, most invasive species not only affect biodiversity; they have major economic costs to productivity.
Whoever forms Australia’s next government, we urge elected leaders to act on the wishes of 96% of surveyed Australians calling for more action to conserve nature.
Euan Ritchie receives funding from the Australian Research Council and the Department of Energy, Environment, and Climate Action. Euan is a Councillor within the Biodiversity Council, a member of the Ecological Society of Australia and the Australian Mammal Society, and President of the Australian Mammal Society.
John Woinarski is a Professor at Charles Darwin University, a director of the Australian Wildlife Conservancy, co-chair of the IUCN Australasian Marsupials and Monotremes Specialist group, a councillor with the Biodiversity Council, and a member of the science advisory committee of Zoos Victoria and Invertebrates Australia. He has received funding from the Australian government to contribute to the management of feral cats and foxes.
Martine Maron has received funding from various sources including the Australian Research Council, the Queensland Department of Environment and Science, and the federal government's National Environmental Science Program, and has advised both state and federal government on conservation policy. She is a member of the Wentworth Group of Concerned Scientists, a director of the Australian Wildlife Conservancy, a councillor with the Biodiversity Council, and leads the IUCN's thematic group on Impact Mitigation and Ecological Compensation under the Commission on Ecosystem Management.
The damage climate change will inflict on the world’s economy is likely to have been massively underestimated, according to new research by my colleagues and I which accounts for the full global reach of extreme weather and its aftermath.
To date, projections of how climate change will affect global gross domestic product (GDP) have broadly suggested mild to moderate harm. This in part has led to a lack of urgency in national efforts to reduce greenhouse gas emissions.
However, these models often contain a fundamental flaw – they assume a national economy is affected only by weather in that country. Any impacts from weather events elsewhere, such as how flooding in one country affects the food supply to another, are not incorporated into the models.
Our new research sought to fix this. After including the global repercussions of extreme weather into our models, the predicted harm to global GDP became far worse than previously thought – affecting the lives of people in every country on Earth.
Weather shocks everywhere, all at once
Global warming affects economies in many ways.
The most obvious is damage from extreme weather. Droughts can cause poor harvests, while storms and floods can cause widespread destruction and disrupt the supply of goods. Recent research has also shown heatwaves, aggravated by climate change, have contributed to food inflation.
Most prior research predicts that even extreme warming of 4°C will have only mild negative impacts on the global economy by the end of the century – between 7% and 23%.
Such modelling is usually based on the effects of weather shocks in the past. However, these shocks have typically been confined to a local or regional scale, and balanced out by conditions elsewhere.
For example, in the past, South America might have been in drought, but other parts of the world were getting good rainfall. So, South America could rely on imports of agricultural products from other countries to fill domestic shortfalls and prevent spikes in food prices.
But future climate change will increase the risk of weather shocks occurring simultaneously across countries and more persistently over time. This will disrupt the networks producing and delivering goods, compromise trade and limit the extent to which countries can help each other.
International trade is fundamental to the global economic production. So, our research examined how a country’s future economic growth would be influenced by weather conditions everywhere else in the world.
What did we find?
One thing was immediately clear: a warm year across the planet causes lower global growth.
We corrected three leading models to account for the effects of global weather on national economies, then averaged out their results. Our analysis focused on global GDP per capita – in other words, the world’s economic output divided by its population.
We found if the Earth warms by more than 3°C by the end of the century, the estimated harm to the global economy jumped from an average of 11% (under previous modelling assumptions) to 40% (under our modelling assumptions). This level of damage could devastate livelihoods in large parts of the world.
Previous models have asserted economies in cold parts of the world, such as Russia and Northern Europe, will benefit from warmer global temperatures. However, we found the impact on the global economy was so large, all countries will be badly affected.
A warm year across the planet causes lower global growth. Pictured: wilted corn crops during drought.wahyusyaban/Shutterstock
Costs vs benefits
Reducing emissions leads to short-term economic costs. These must be balanced against the long-term benefits of avoiding dangerous climate change.
Recent economic modelling has suggested this balance would be struck by reducing emissions at a rate that allows Earth to heat by 2.7°C.
This is close to Earth’s current warming trajectory. But it is far higher than the goals of the Paris Agreement, and global warming limits recommended by climate scientists. It is also based on the flawed assumptions discussed above.
Under our new research, the optimal amount of global warming, balancing short-term costs with long-term benefits, is 1.7°C – a figure broadly consistent with the Paris Agreement’s most ambitious target.
Our new research shows previous forecasts of how such warming will affect the global economy have been far too optimistic. It adds to otherrecent evidence suggesting the economic impacts of climate change has been badly underestimated.
Clearly, Earth’s current emissions trajectory risks our future and that of our children. The sooner humanity grasps the calamities in store under severe climate change, the sooner we can change course to avoid it.
Timothy Neal does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
