Out there: An Australasian bittern in wetlands.
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The endangered Australasian bittern is being heard in near-record numbers in the Barmah-Millewa Forest, giving hope to bird enthusiasts and scientists alike.
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Around 30 per cent of the nation’s remaining bittern population is estimated to live in reedy wetland habitats in Barmah and Millewa.
With only 1300 estimated to remain, this elusive night-calling, well-camouflaged bird is nationally endangered.
The bird, which is part of the heron family, blends in to its natural environment and is described as having a booming call.
One of the reasons for the species’ decline is the changing water levels, including last October’s floods.
The Living Murray Program, run by NSW Parks and Wildlife Service and Victorian partners, has monitored the Barmah-Millewa Forest bittern population for the past seven years.
This has included recording a series of deep growls when males are in a search for a mate.
NPWS project officer Brady Cronin said the number of male bitterns calling this year was among the highest ever recorded.
“Monitoring data has identified changes in the timing of the bittern calling as a result of the 2022-23 flood, one of the largest of the decade, where water levels rose and dropped by around three to four metres in the Barmah-Millewa Forest,” Mr Cronin said.
The NSW Government’s Water for the Environment Program is playing a critical role in supporting Australasian bittern population recovery within the inland wetland systems.
Senior environmental water management officer Paul Childs said the NSW Department of Planning and Environment’s environmental water managers worked with river operators to deliver water for the environment annually into sites where bitterns were known to breed.
“These flows are designed and timed to mimic the natural flow regime and provide ideal conditions for a range of other waterbirds and wetland-dependent plants and animals too,” Mr Childs said.
“This outcome highlights the importance of long-term monitoring that helps to inform the adaptive management of environmental water and site-based management activities such as predator control, which are essential components for building Australasian bittern populations.”
Recent research conducted by Dr Elizabeth Znidersic and her team from the Gulbali Institute at Charles Sturt University has provided insight into the secretive life of the Australasian bittern by deploying sound recorders throughout the forest.
“The research shows that male Australasian bitterns started their breeding calls before the peak of the flood, stopping during the peak month, then resumed calling after flood waters slightly receded, and nesting habitat became available again,” Dr Znidersic said.
Home surrounds: Reed beds in the Murray Valley National Park are a key habitat for Australasian bittern.
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To ensure bittern chicks successfully fledged so late in the season, additional water for the environment was delivered into the wetlands.
The NPWS and Parks Victoria bittern project is funded by the Murray-Darling Basin Authority TLM Program and the Victorian Government Sustainability Fund Community Action for Biodiversity (Icon Species) project.
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