Drier conditions across many parts of Australia have led to a drop in waterbird numbers by nearly 50 percent.
UNSW’s annual waterbird survey found that following the wet La Niña years, drier conditions in 2024 resulted in a drop in waterbird numbers and breeding.
Professor Richard Kingsford said researchers spotted 287,231 birds in this year’s survey, down from 579,641 birds in 2023.
Professor Kingsford said the study covered a third of the continent and provided one of Australia’s most important long-term datasets on the health and biodiversity of the country’s river and wetland areas.
He said the 2024 numbers were in the middle of the range across the 42 years that the survey had been running.
“We know that when it is starts to dry up, the floodplains dry up and waterbirds do not have the food to breed in large numbers, so they concentrate on remaining lakes and swamps, which is what we saw this year.”
Professor Kingsford said this year’s data on overall numbers, number of species breeding and wetland area, three of the four major markers of waterbird health, had also continued to show significant long-term declines over time.
“We had a good bounce in numbers after good breeding in the flood years of 2021 and 2022, but numbers have now dipped below the long-term average again, with little breeding in 2023 and 2024.”
He said the scientists found waterbirds were most abundant in the temporary wetlands of the Georgina-Diamantina River system in northwestern Queensland, with Lakes Mumbleberry and Torquinnie supporting more than 50,000 waterbirds, which was 17 percent of all birds observed this year.
“Drier conditions have continued to develop over eastern Australia, exacerbated by higher temperatures in the context of climate change. This is contributing to a faster drying out of wetlands.”
Professor Kingsford said this year’s total area of wetlands was 122,283 ha, a decrease from the previous flood year of 2022 and well below the long-term average.
“In the south-east of Australia, there has been a decrease in April to October rainfall of around 9 percent since 1994, and more frequent periods of below average rainfall.
“This has meant decreasing stream flows at most gauges across Australia since 1970, particularly in the Murray-Darling Basin, as recorded by CSIRO this year.”
