News release

From: Flinders University

Flinders University palaeontology researchers - with local fossil experts - have discovered how prolific shorebirds, including the Plains-wanderer, once lived across South Australia’s South-East during wetter times up to 60,000 years ago.

The experts link a phase of pronounced drying from about 17,000 years ago as being the likely cause for the decline of many of the nine or more fossil shorebird species found in just one of the World Heritage-listed Naracoorte Caves.

“Shorebirds are rare in the fossil record, so finding so many in one cave (Blanche Cave) was a surprise,” says Flinders PhD candidate Karl Lenser, the lead author of the study published in Palaeontologia Electronica.

“This shows that the wetlands and mudflats, where birds like plovers, sandpipers and snipes feed, were much more common in the region during the last Ice Age.”

Climate change and shrinking habitat are causing living shorebird populations in Australia to fall. Understanding how these species responded to past climate change may be key to predicting how populations will be affected in the future, researchers say.

Researchers were particularly puzzled by the fossils of one bird. The Plains-wanderer – a small, endangered bird which is found predominantly in small populations in Victoria and New South Wales – were one of the most common species of bird identified in the study.

Over half of the nearly 300 bones examined in the study were identified as Plains-wanderers.

“Living Plains-wanderers are now very selective about their habitat, but other fossils from Naracoorte show that the area was probably a woodland … a far cry from the treeless open grasslands Plains-wanderers inhabit today,” says Mr Lenser, from the Flinders College of Science and Engineering Palaeontology Laboratory.

Naracoorte is the only fossil site in Australia where Plains-wanderers are found in such high numbers, suggesting that events in the last 14,000 years caused a large decline in populations of this intriguing bird.

This decline was associated with the Plains-wanderer becoming limited to a narrower range of habitats where trees are absent, rather different to the woodlands it occupied during the last hundred thousand years.

Study co-author, Flinders University Associate Professor Trevor Worthy, says: “This sample of shorebirds is also extra special as it documents migratory species that annually fly from the Northern Hemisphere to spend the boreal winter in Australia.

“These include three species of Calidris sandpipers and Latham’s snipe Gallinago hardwickii. Also common in the fossil assemblage is the Double-banded plover which migrates from Australia to New Zealand to breed.

“Two birds were less than a year old indicating that they had flown as fledglings the 2000 km distance from New Zealand only to be captured by an owl near Blanche Cave at Naracoorte,” says Associate Professor Worthy.

The Naracoorte Caves form part of the Australian Fossil Mammal Sites UNESCO World Heritage Listing.

“There is still a lot we don’t know about birds in Australia during the last Ice Age, but fossils from caves like those at Naracoorte are helping to fill this gap,” adds Mr Lenser.

Co-author Dr Liz Reed, from Adelaide University, adds: “The Naracoorte Caves preserves a half million-year record of biodiversity in southeast South Australia.

“As this study clearly demonstrates, the caves provide a window into pre-European landscapes and yield information relevant to the conservation of threatened species today.

“Visitors to Naracoorte Caves can view the excavations and learn more about the science of South Australia’s only World Heritage Area.”

The Naracoorte Caves are located on the Traditional Country of the Boandik, Potaruwutij, Jardwadjali, and Meintangk Peoples.

The new article, ‘Fossil shorebirds (Aves: Charadriiformes) reveal trends in Pleistocene wetlands at Naracoorte Caves, South Australia’ (2025), by KM Lenser, EH Reed and TH Worthy has been published in Palaeontologia Electronica DOI: 10.26879/1608.