The endangered Australasian bittern likes to keep a low profile, and if it feels threatened it’s known to stand still, extend its wings and pretend to be a reed.

It has the nickname ‘bunyip bird’ because its eerie deep hoot is said to resemble that of a bunyip — a mythical creature that is said to inhabit swamps and waterholes.

The secretive, camouflaged bird is partially nocturnal and likes to be heard and not seen.

But the booming call of the bittern has been detected at Lagoon of Islands in Tasmania’s central highlands for the first time in 40 years, in a sign that the environment is healing after damming damage was reversed.

Bird expert Geoff Shannon spotted a pair of bitterns with chicks through his binoculars on a chance visit to the area.

“I was amazed, it was pure chance that I decided to stop,” he told Joel Rheinberger on ABC Radio Hobart.

“It’s probably one of the memories of my life in terms of birding, and I’ve done a lot of birding.

“It’s the best record of breeding in Tasmania we’ve had for many years I would think.”

Dr Shannon said he hadn’t seem a bittern in Australia since the 1980s and said numbers have dramatically reduced in the past few decades.

Bittern call recorded

The elusive bittern is a large heron and can stand about one metre tall.

“It’s a big bird, it’s bigger than the white faced heron and heavier,” Dr Shannon said.

“If they are frightened they stand up absolutely straight and hold still and the streaking on the neck looks just like reeds.”

Scientists think there could be fewer than 1,000 bitterns in Australia, and Dr Shannon said there were probably only 50-100 in Tasmania.

Dr Shannon became involved in the citizen science project CallTrackers by the Bookend Trust that records the sounds of animals at night.

The project was initially focused on bats, but has now also turned to bitterns.

Dr Shannon managed to record a bittern at Longford in the state’s north, and recorders at the Lagoon of Islands have also detected the bird’s mating call.

He said the call could carry 500-1,000 metres.

Damage undone

Lagoon of Islands, 40 kilometres north of Bothwell, was an unusual wetlands known as a schwingmoor, where roots join to make floating reed mats that are anchored into sediment around the perimeter of the lagoon.

It was dammed in 1964 by the then-Hydro Electric Commission, not for electricity generation, but to provide water to irrigators along the Ouse River after water was diverted from the Waddamana Power Station into the new Poatina scheme.

The damming of the lagoon raised the water level, killing the “islands” and creating water quality problems, especially in the 1990s and 2000s.

Hydro Tasmania environmental scientist Bec Sheldon has been working on the restoration of the wetlands since 2019.

She said the lagoon was drained in 2012 and in 2013 the dam wall was removed and rehabilitation began.

“Prior to damming it was an area that had a very significant ecosystem of floating reed mats and floating islands,” she said.

“We looked to re-create the natural hydrology of that system and left it largely alone to do its own thing.

“Wetlands are very dynamic systems and often if you can restore the natural hydrology the rest will look after itself and that’s exactly what we’ve seen happen.”

She said the wetlands’ vegetation started returning over time.

“In seven or eight years we’ve seen it return to about 90 per cent vegetation cover and now we are seeing species like [the bittern] return,” she said.

“Unfortunately the islands aren’t floating anymore, that might be the last piece of the puzzle.”