Record flooding in New South Wales wetlands triggers bird breeding bonanza

Bird breeding bonanza in NSW. (Joanna Woodburn)

It has been a tough few years for Australia's aquatic wildlife with droughts and bushfires. 

But record-breaking flooding in western New South Wales has provided a lifeline.

University of New South Wales river ecologist Richard Kingsford said the conditions were important for a range of waterbird species because they hadn't been getting as much opportunity to breed as they did in the past.

"A big event like this essentially allows them to bring back their numbers," Professor Kingsford said.

The Booligal Wetlands are tucked away on the edge of the Hay Plains. (ABC Central West: Xanthe Gregory)

The flush of floodwater has seeped into wetlands and triggered one of the most widespread bird breeding events in decades. 

Hundreds of thousands of waterbirds have converged on wetlands such as those at Booligal near Hay in far western NSW.

Some chicks become separated from their parents and have to fend for themselves. (ABC Central West: Joanna Woodburn )

The Booligal Wetlands are fed by the Lachlan River which cuts through the centre of NSW.

The river was subject to several months of major flooding late last year. 

"What happens in these big floods is that they produce a tremendous flush of things to eat for waterbirds," Professor Kingsford said. 

"Everything from small invertebrates, to plants, to frogs, to many fish. 

"You're talking about waterbirds like pelicans right through to swans and small wading birds that are feeding across that broad spectrum of food."

One of the tens of thousands of chicks that have hatched at Booligal Wetlands. (ABC Central West: Xanthe Gregory)

Teams from the University of New South Wales in Sydney are visiting Booligal once a fortnight for six months to monitor the bird breeding event. 

They wade up to their necks in water that has created the perfect sanctuary for an array of species to breed.

Tens of thousands of waterbirds have converged on the Booligal Wetlands to breed. (ABC Central West: Joanna Woodburn)

"First you need the flood, then the water needs to stay around [and] the water needs to stay at the right depth," UNSW researcher Jana Stewart said. 

Breeding bonanza 

The team tags nests which will then be checked for eggs and how many chicks hatch. 

Richard Kingsford says bird populations are not as dense because of the expanse of water. (Supplied: UNSW)

Ms Stewart said the wetlands were home to straw-necked ibis, glossy ibis, white ibis, royal spoon bills, ducks, wading birds, as well as fish and invertebrates.

"It feels very special when you come into these places," she said. 

"We have between 30,000 and 50,000 breeding pairs and you're maybe the only person that these birds have seen so far.

"Seeing some of the chicks hatch in front of you, it feels very special."

Clutches of eggs waiting to hatch at Booligal Wetlands. (ABC Central West: Xanthe Gregory)

The birds act as a barometer for the rest of the ecosystem. 

If they can breed and raise their young, it means the water quality is high and other animals are also flourishing. 

"It looks really good; we can see the water is really clear, there's a lot of movement, a lot of chicks around," she said. 

Pelicans perch on slivers of dry ground at Lake Numalla in Currawinya National Park. (Supplied: UNSW Centre for Ecosystem Science  )

Awash with water

The survey is two-fold. 

The teams are also monitoring the health of the water.

They collate the data on behalf of the Commonwealth Environmental Water Holder. 

The information is used to help determine whether or not more releases are needed from upstream to sustain the wetlands and wildlife. 

Storages such as Dartmouth Dam in Victoria have been spilling due to the volume of water.  (Supplied: UNSW Centre for Ecosystem Science)

"The critical thing for these breeding birds is they like to be nesting above water, and that's really so they're protected from predators," Professor Kingsford said. 

"This is such a big flood event that it's not really envisaged that we need extra water to get them through because there's so much water around."

Loic Julliard and Jana Stewart are among the UNSW researchers studying the Booligal Wetlands. (ABC Central West: Joanna Woodburn)

University of New South Wales has also completed its annual aerial bird count which monitors up to 2,000 sites across eastern Australia. 

"They're very thinly spread across the Murray Darling Basin at the moment," Professor Kingsford said.

"We find that the waterbirds are breeding everywhere."

He said the benefits of the major flood could not be overestimated for birds because of the years of drought.

"The capacity to rebound is reduced," he said. 

"If you have got fewer birds in the system to be able to actually take advantage of a big flood like this, that comes down to the big issue that we've got in terms of managing the system. 

"It's those sort of small to medium floods that we've lost a lot of."

The Lachlan River has made a rare connection with the Lower Murray Darling Basin at the Great Cumbung Swamp. (Supplied: UNSW Centre for Ecosystem Science)

Nests drowned

While the recovery has been widespread, there has been too much water in some parts of NSW. 

The state's largest natural inland lake, near West Wyalong, lost a colony of about 10,000 ibis when their nests were flooded.

 Mal Carnegie says there has been too much water at Lake Cowal for widescale bird breeding. (ABC Central West: Joanna Woodburn)

Lake Cowal Foundation projects manager Mal Carnegie said next summer should be more successful.

"If we go back to a more normal sort seasonal pattern, I'd expect those areas further west would be drying up and we'd expect to see greater numbers of birds here," he said. 

"The habitat is going to be in good condition on the back of this flooding and the water level will be more appropriate for nesting."