In the vast, arid landscapes of South Australia's northeast, on the lands of the Adnyamathanha and Wilyakali, a surprising discovery is changing our understanding of one of Australia's most endangered birds.
Authors
- Saskia Gerhardy
PhD Candidate, School of Biological Sciences, University of Adelaide
- Steven Delean
Lecturer in Biostatistics and Ecology, University of Adelaide
The plains-wanderer (Pedionomus torquatus) has long hovered on the brink of extinction . Conservation efforts focus on protecting its known grassland habitats, mainly in Victoria and and New South Wales. But our new research shows more than 250 of these birds are thriving in habitats previously considered unsuitable, on the western edge of its range.
We used tracking devices - attached to a harness resembling a tiny backpack - to discover that this new population prefers open shrublands to grasslands. This could change how we conserve one of Australia's most unique birds.
Studying the Goldilocks bird
Most people agree Australia is home to some pretty special birds, but the plains-wanderer often goes unnoticed. This small, mottled brown, ground-dwelling bird is the sole surviving member of an ancient lineage. It's often called a "living fossil" because its closest relatives died out long ago.
It's so unique that in 2018 the Zoological Society of London put the plains-wanderer on top of its "evolutionarily distinct and globally endangered" bird list . Fewer than 2,000 plains-wanderers remain in the wild.
Known as a habitat specialist, the plains-wanderer has been nicknamed the " Goldilocks bird " because its survival depends on conditions being just right .
Historically, this included well-managed native grasslands in Victoria and NSW, while habitat in SA was considered too degraded or unsuitable.
Our new research challenges this view, uncovering a population thriving in habitat nobody expected the species to use.
Strap on the birdie backpacks
Against all expectations we found 272 plains-wanderers living in Boolcoomatta Station Reserve , 100km west of Broken Hill in semi-arid rangeland.
To learn more about this new population, we used miniature GPS data loggers to track their movements for a month. Then we used VHF (very high frequency) devices to locate the birds, so we could retrieve and download the information.
Both devices are lightweight and designed to sit comfortably between the birds' wings, like a tiny hiking pack. Researchers conducted extensive testing with captive birds to ensure the fit was safe and comfortable.
Once we had ethics approval in place, we fitted 29 plains-wanderers with these miniature backpacks. Then, like following breadcrumbs through the bush, we traced the steps of our tracked birds to find the habitats they selected.
Choosing shrublands over grasslands
We found this new population of plains-wanderers consistently selected open shrublands dominated by a low-growing woody herb, Sclerolaena.
This prickly, hardy, drought-tolerant plant does not seem like particularly hospitable habitat. It's more often associated with grazed rangelands than endangered birds. But time and again, our GPS-tracked birds chose these sparse, open areas. Their preferred habitat featured about 55% plant cover with large patches of bare ground. The plants were an average 11cm tall.
Grassy places could also be found in the landscape. But these areas were particularly dense, providing the wrong kind of cover for plains-wanderers. The birds' consistent avoidance of these denser grasslands suggests vegetation structure, rather than just plant species, is key.
This challenges decades of ecological thought. The plains-wanderer, long considered a "grassland specialist", may actually be more selective about vegetation structure than species composition. In other words, habitat use is not solely about grass cover but the right mix of plant height, density and bare ground.
Unanswered questions
Our discovery of more than 250 so-called grassland specialists in shrubland raises important questions about the management of this threatened species.
For decades, conservation efforts have focused on protecting core habitat of the plains-wanderer in NSW and Victoria. While these areas remain crucial, our findings suggest the species lives in a broader range of habitats than previously thought. Interestingly, the habitat we found is widespread in SA's arid interior, opening up new possibilities for conservation in areas often dismissed as unsuitable.
Peripheral populations of threatened species are often overlooked, but they remain vital for survival of a species. These populations may have unique traits, behave differently, or buffer declining core habitats.
Our findings show conservation shouldn't focus solely on assumptions about habitat. If we only search where we expect to find a species, we risk missing important parts of the bigger picture - or, in this case, vital parts of the population.
Yet, there is much we still do not know about this population. Where did it originate? How far does its range extend? How will it cope with droughts and climate change? Our discovery raises more questions than answers.
To better understand this population, we are now conducting genetic analyses to explore how it interacts with the core population. The results should tell us more about how closely they are connected.
We are also incorporating this new data into computer models to identify other possible hidden populations, refine the species' range, and aid in population discovery.
Perhaps most importantly, this research allows us to protect not just the places we've always looked - but the places we've overlooked.
Keep searching for more surprises
It's uncommon to write a positive story about a species listed as critically endangered, especially when they're in better condition than expected.
Even as biodiversity loss accelerates, discoveries like this remind us nature still holds surprises.
This find serves as a strong reminder to keep searching, not just in the usual spots, but in the misunderstood areas at the edges of a species' range. Because sometimes, hope can be found in the most unexpected places.
This research was made possible through Bush Heritage Australia funding, and with the support of the Grubb foundation, BirdLife Australia, Nature Conservation Society of South Australia, and the Schultz Foundation.
Steven Delean 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.
