The pervasive presence of shorebirds, coupled with their intrinsic reliance on littoral and marshy ecosystems, confers upon them the status of potent paleoclimatic indicators. While avian wading species are seldom encountered in the paleontological strata, Pleistocene formations unearthed within the Naracoorte Caves World Heritage Area in South Australia have unexpectedly yielded a significant concentration of shorebird remnants. A recent scrutiny of fossilized remains from the Naracoorte Caves elucidates the former prevalence of wetlands and their subsequent attenuation as global temperatures escalated approximately 60,000 years ago. The researchers posit that a period of marked aridity, commencing around 17,000 years ago, was the probable catalyst for the decline observed in numerous of the nine or more extinct shorebird species identified within a single Naracoorte Cave.
The red knot (Calidris canutus), juvenile, near Gourinet, Brittany, France. Image credit: Stephan Sprinz / CC BY 4.0.
“The scarcity of shorebirds in the fossil record renders the discovery of such an abundance within a single cavern (Blanche Cave) a remarkable occurrence,” commented Karl Lenser, a doctoral candidate at Flinders University.
“This finding underscores the significantly greater extent of marshlands and intertidal zones, vital feeding grounds for birds such as plovers, sandpipers, and snipes, within the region during the concluding glacial epoch.”
Contemporary shorebird populations across Australia are experiencing a reduction, attributed to the dual pressures of climatic shifts and habitat degradation.
Gaining insight into the adaptive responses of these species to past climatic fluctuations may prove instrumental in forecasting their future population trajectories.
Lenser and his investigative team were particularly intrigued by the fossilized fragments of a specific avian species.
The plains-wanderer – a diminutive, endangered bird sparsely distributed in specific locales within Victoria and New South Wales – emerged as one of the most frequently identified species in the analysis.
In excess of half of the nearly 300 avian bones meticulously examined by the researchers were attributable to plains-wanderers.
“Current plains-wanderers exhibit a pronounced degree of habitat selectivity, yet complementary fossil evidence from Naracoorte suggests the area was likely forested… a stark contrast to the treeless open grasslands that plains-wanderers inhabit in the present day,” Lenser stated.
Naracoorte stands as the sole paleontological site in Australia where plains-wanderers are discovered in such prolific numbers, indicating that environmental transformations over the last 14,000 years precipitated a substantial diminution in the populations of this distinctive avian group.
This population decline coincided with a restriction of the plains-wanderer’s habitat preferences to more confined, treeless environments, a significant divergence from the woodland ecosystems it frequented over the preceding hundred millennia.
“This collection of shorebird specimens is exceptionally noteworthy, as it documents migratory species that undertake an annual journey from the Northern Hemisphere to winter in Australia,” observed Dr. Trevor Worthy of Flinders University.
“Among these are three species of sandpipers belonging to the genus Calidris, along with the Latham’s snipe (Gallinago hardwickii).”
“Furthermore, the double-banded plover, which embarks on a migratory route from Australia to New Zealand for breeding purposes, is also a common constituent of the fossil assemblage.”
“The remains of two individuals, both less than a year old, indicate they had journeyed as fledglings the approximate 2,000 km distance from New Zealand, only to be predated by an owl in proximity to Blanche Cave at Naracoorte,” Dr. Worthy elaborated.
“While our understanding of Australian avifauna during the last Ice Age remains incomplete, fossil discoveries from subterranean sites such as those at Naracoorte are instrumental in bridging this knowledge gap,” Lenser added.
“The Naracoorte Caves preserve a half-million-year chronicle of the biodiversity present in southeastern South Australia,” stated Dr. Liz Reed from Adelaide University.
“As unequivocally demonstrated by this research, these caves offer a valuable portal into pre-European landscapes and furnish crucial data pertinent to the contemporary conservation efforts for endangered species.”
“Visitors to the Naracoorte Caves have the opportunity to observe ongoing excavations and deepen their comprehension of the scientific significance of South Australia’s sole World Heritage Area.”
The research findings have been officially disseminated online through the journal Palaeontologia Electronica.
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Karl M. Lenser et al. 2026. Fossil shorebirds (Aves: Charadriiformes) reveal trends in Pleistocene wetlands at Naracoorte Caves, South Australia. Palaeontologia Electronica 29 (1): a2; doi: 10.26879/1608
