PREVIEW

The endangered Australasian bittern has been spotted for the first time in 40 years at the Lagoon of Islands on Tasmania’s Central Plateau.

Bird expert Geoff Shannon told ABC Radio Hobart that he saw a pair of bitterns with chicks through his binoculars while visiting the area.

“I was amazed, it was pure chance that I decided to stop,” Dr. Shannon said. “It's probably one of the memories of my life in terms of birding, and I've done a lot of birding.”
He added, “It's the best record of breeding in Tasmania we've had for many years I would think.”

Dr. Shannon also recorded the bird’s call for the citizen science project CallTrackers, by the Bookend Trust.

“It was a privilege hearing that booming call on the tapes. It’s been more than 40 years since bitterns have been recorded at Lagoon of Islands,” Hydro Tasmania environmental scientist Bec Sheldon gushed after listening to the recording. “We’re now reaping the fruits of our rehabilitation efforts, seeing this fantastic species move back in and the site become a self-sustaining, productive, natural wetland.”

Also known as the brown bittern, the ‘bunyip bird’, the matuku hūrepo, or by its Latin name Botaurus poiciloptilus, the Australasian bittern is a species of heron found in wetlands which has been listed as endangered in Australia and New Zealand.

The bird is known for its booming call and its camouflage behaviour – standing still, extending its wings, and pretending to be a reed.

An Australasian bittern’s call can carry 500-1,000 metres.

“It's a big bird, it's bigger than the white-faced heron and heavier,” Dr. Shannon described. “If they are frightened they stand up absolutely straight and hold still and the streaking on the neck looks just like reeds.”

Researchers have estimated that fewer than 1,000 Australasian bitterns remain in Australia, while Dr. Shannon specified only 50-100 of those lived in Tasmania.

Dr. Shannon exclaimed that he hadn’t seen the one-metre tall bird since the 1980s.

The Australasian bittern’s decline in Tasmania has been attributed in part to a dam built in 1964 by the Hydro Electric Commission on the Lagoon of Islands, turning a schwingmoor wetlands into an irrigation source.

As work continued into the 1990s and 2000s, the dam introduced water quality problems and killed the wetland ‘islands’ where the Australasian bitterns lived.

Sheldon recalled that the lagoon was drained in 2012 and the dam wall was removed in 2013 – then the real 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.”

She continued, “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.”

The environmental scientist speculated that as vegetation returned over time, the Lagoon of Islands once again became a habitat which the Australasian bittern could return to.

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