This shy, reclusive species inhabits shallow and freshwater wetlands in south-east Australia. Australasian bitterns are extremely difficult to detect as they hide among tall vegetation. Luckily, they can be monitored acoustically; their presence is signalled by a booming call made by the male birds.
Unfortunately, this species is in decline. BirdLife Australia reports that there was a decline of more than 50 percent in Australasian bitterns between the late 1970s and early 2000s, undoubtedly exacerbated by the Millennium drought.1
Australasian bitterns prefer shallow ephemeral wetlands with dense emergent vegetation. Many of these wetlands have been lost due to river regulation and water diversion for human needs.
Over the last four years, BirdLife Australia has been assessing the value of rice crops in the Riverina (in south-western New South Wales) for Australasian bittern and has confirmed that a large population of bitterns moved into rice crops, with some breeding activity occurring. The Bitterns in Rice Project also tracks a number of birds to find out where they travel during and after breeding.
In 2015-16, Robbie, the first Australasian bittern to be tracked, made his way to Victoria and headed south-west to the mouth of the Glenelg River, eventually arriving at Long Swamp. He stayed there for months before starting his journey home to the Riverina. In May 2016, Neil, another tracked bittern, left the Riverina and took a 450 km journey east. He was eventually tracked to Moodie Swamp, a Goulburn-Broken wetland which is an important environmental watering site.
"It's great to see Neil arrive at Moodie Swamp," says Jo Woods, Environmental Water Project Officer at Goulburn Broken Catchment Management Authority.
"Interestingly, we'd provided Moodie Swamp with water back in May 2014, primarily to promote the growth of southern cane grass which is excellent habitat for Australasian bittern. We then managed to acoustically record bittern calls the following September. Off the back of this, Moodie Swamp received environmental water in the summer of 2014-15 and again in late autumn of 2016, coinciding with Neil arriving at Moodie Swamp. The fact that Neil chose to head to Moodie Swamp this year gives us an excellent signal that the watering is doing its job!"
1 Silcocks, Webster & Herring, cited in Birds of the Murray Darling Basin, 2014, BirdLife Australia.