More than 200,000 birds have been sighted in the wetlands, north of Hay in a major breeding event. 

Office of Environment and Heritage director Graeme Enders said he and other experts haven’t seen an event anything like it for over for 20 years. 

Mr Enders said significant rainfall had made the once-in-a-generation event possible. “

“(The rain) filled dams, boosted water allocations and brought some of the most significant environmental benefits experienced in years”.

“The high water flows over the past five months have inundated swamps and wetlands in the Lachlan River valley and we are now seeing a major colonial waterbird breeding event,” he said. 

“It’s mainly Straw-necked Ibis, but we are also seeing the return of migratory and nomadic birds, and some threatened species like the Blue-billed Duck. 

“Monitoring indicates the Booligal Wetlands are supporting more than 100,000 Ibis nests.

With an average of three eggs per nest we can expect to see at least 200,000 Ibis fledge to adulthood well above natural mortality.

“This breeding event is a significant increase on the last event at the end of the millennium drought in 2010-11, when ecologists counted around 64,000 nests in the same area. 

“The majority of the young here now are either close to or have fledged, and … are now busily putting on weight to support their dispersal across (the country).

“As part of the monitoring we are also looking at what food the birds are eating by doing a ‘scat analysis’.

(They) look at their droppings to see what they are feeding on and how far they travel to find that food source.”

While environmental water is usually responsible for the maintenance of the wetlands, the unusually high migration numbers are believed to be a result of the Lachlan flood. 

Commonwealth Environmental Water holder David Papps said the event was a “recovery of bird populations as well as the regeneration of native vegetation”.

“In the event the system begins to dry out too soon, follow up environmental watering may be provided to support the birds,” he said. 

Mr Papps said environmental water would help ensure bird breeding was completed, with chicks able to reach maturity. 

The birds’ progress will be monitored across summer.