An aerial survey by UNSW researchers reveals that waterbirds and water have vanished from the northern reaches of Macquarie Marshes wetland, north of Dubbo.
"This year we didn't find a single bird in Marshes' northern region. It was heartbreaking," says UNSW river and waterbird expert Richard Kingsford.
The decline in water and bird life stem from the present drought and long-term effects of over-allocating water for irrigation. These are causing catastrophic changes on the rivers of the Murray-Darling Basin.
It is the worst finding in the 25-year history of annual aerial waterbird surveys of eastern Australia done by UNSW scientists. The Macquarie Marshes wetland is unique to Australia because of its large colonies of breeding ibis and egrets.
"In the 1980s we averaged 20,000 waterbirds from more than 20 species in the Marshes," Professor Kingsford says. "In the 1990s that figure dropped to 5,000 birds from 13 species and since 2000 we have averaged around 600 birds from just nine species."
Kingsford, who has just flown his 22nd year of the survey, believes the internationally-listed wetland is now collapsing. "This is one of Australia's most famous bird-breeding sites but we've had no bird sightings in the past seven years. Usually they breed every second year."
"The 2007 survey revealed that waterbirds and water were virtually absent from the Murray-Darling Basin and few wetlands held large numbers of waterbirds. Anyone who is privileged to see a lake with tens of thousands of waterbirds realises the significant toll that our overexploitation of rivers is causing," Kingsford says.
The survey covers about a third of continental Australia and is done in collaboration with the NSW Department of Environment and Climate Change and other state conservation agencies. Survey teams fly east-west along ten 30km-wide survey bands stretching from Victoria to the Northern Territory border. Two hundred kilometres separates each of the survey bands. The first of these survey bands spans 1,200kms from the Whitsunday Islands across to Mt Isa. The last of the survey bands is south of Melbourne.
Occurring in October each year, the survey counts waterbirds in eastern Australia on about 2,000 wetlands. It is one of Australia's most important long-term data sets on the health and biodiversity of our river and wetland environments, and one of few like it in the world.