• Charles Sturt University researchers are investigating the impact of environmental water activities on Australasian Bittern breeding
• The research is analysing bird call and water activity data from the last seven years
• Findings of the research could assist in informing recommendations for the delivery of water for the environment to support bittern breeding in the Murrumbidgee

Researchers are investigating how environmental watering actions could promote the breeding of an endangered Australian bird species.

Postdoctoral Fellow in the Charles Sturt Gulbali Research Institute for Agriculture, Water and Environment Dr Elizabeth (Liz) Znidersic is the environmental research scientist and ecologist leading the project.

Funded by the Commonwealth Environmental Water Holder (CEWH), the research is investigating the relationship between the timing and duration of water for environmental deliveries and the calling activity of the endangered Australasian Bittern, or ‘Bunyip bird’.

“The reason the calling activity of the bittern is important to understand is because it’s one of the only ways to assess their numbers,” Dr Znidersic said.

“The bittern is an elusive and well-camouflaged bird, so often difficult to detect among its preferred vegetation of reeds, rushes and rice, but when males are in search of a mate, they have a distinctive ‘booming’ call which can resonate for more than a kilometre across a quiet wetland.

“Consequently, they are more often heard than seen, which provides an opportunity for researchers to gain insight into population and breeding activity, as well as an understanding of the watering needs of this species.”

Researchers are using previously deployed automated call recorders and depth loggers from key Lower Murrumbidgee Monitoring, Evaluation and Research (MER) wetland sites.

The team has been collecting data since 2016 from these wetlands, where Australasian bitterns are known or expected to reside, allowing researchers to evaluate the calling activity in response to water depth and temperature from the last seven years.

Dr Znidersic has developed a call recognition model which identifies Australasian bittern calls, helping to evaluate large datasets and audio collections more efficiently.

“The challenge of detecting Australasian Bitterns is a result of their irregular calling pattern and that they call mostly in the hours of darkness,” she said. “This means we need to record continuous audio data to increase the detection probability which can amount to years of listening.

“Therefore, we use an automated computer analysis technique to detect the Australasian Bittern calls.”

The research team hopes to use their findings to help develop and inform recommendations for the delivery of water for the environment to support bittern breeding in the Murrumbidgee.

The project will also assist in developing guidelines for water managers, helping outline the ideal environmental watering regimes (timing, duration, depth, and volume) necessary to stimulate successful breeding and survival of Australasian Bitterns.

The research is part of the FlowMER program, which monitors the ecological response to Commonwealth environmental water delivery to wetlands along the Murrumbidgee. This includes water quality, vegetation, waterbirds, wetland and riverine fish, frogs and turtles.

ENDS