
Waterbird numbers in eastern Australia have plummeted by 50% compared to 2023 due to drier conditions, according to one of the country’s largest wildlife surveys.
The eastern Australian waterbird aerial survey, conducted annually since 1983, is one of the world’s longest continuous bird counts, covering a vast area of 2.7 million square kilometres—equivalent to 11 times the size of the UK.
This year’s survey recorded 287,231 birds, a sharp drop from the 579,641 observed in 2023. It marks the 22nd highest total in the survey’s 42-year history, falling well below the long-term average. The survey tracks more than 70 waterbird species, monitoring their distribution, breeding, and changes in the major rivers and wetlands of the Murray-Darling Basin.
Prof. Richard Kingsford, director of the Centre for Ecosystem Science at the University of New South Wales and leader of the survey, expressed cautious optimism after recent wet years driven by triple La Niña events. However, the expected sustained boost in bird numbers has not materialised.
“In 2021 and 2022 there was a lot of flooding everywhere, and we know that there were a lot of birds breeding, but we just haven’t seen the same sort of recovery,” he said.
Three of four key indicators of waterbird health—overall population, breeding activity, and wetland area—showed declines, continuing a long-term downward trend. Breeding abundance was particularly low, falling well below historical averages, while the total wetland area recorded, 122,283 hectares, was significantly below the long-term norm.
“The areas that these birds breed in and rely on are floodplain areas,” Kingsford said. “So much of what we’ve done in building dams and diverting water has [affected] that flood water that’s so critical for the wetlands.
“We’re also increasingly worried about the effects of climate change in terms of the drying out of the south-east of the continent.”
Kingsford attributed the drying wetlands to the intensifying climate crisis but acknowledged the Murray-Darling Basin Plan as an essential restoration initiative for rivers. “What our data are indicating is probably there’s been some decrease in the rate of decline, not necessarily a complete restoration. We’re definitely making a difference in terms of putting water back into rivers.
“But it’s the big floods that are very important for these systems and the biodiversity. We’ve got to think about that in terms of the next review of the Basin plan.”
This year, the team also monitored for signs of avian influenza outbreaks, particularly the H5N1 strain, which has caused mass mortality in wild bird populations globally. No significant instances of mass mortality were observed.
“We didn’t find any, which is always a relief,” Kingsford said.
The most abundant waterbird populations were found in the temporary wetlands of the Georgina-Diamantina river system in north-western Queensland. Notably, Lakes Mumbleberry and Torquinnie accounted for 17% of the total birds observed, with approximately 50,000 individuals.
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