Menindee Lakes: Ecologist finds 400 dead pelicans at Lake Cawndilla

Hundreds of native pelicans have dropped dead at a highly significant wildlife wetland, with authorities left scrambling to explain what killed them.

Wetland Revival Trust Ecologist Damien Cook made the shocking discovery at Lake Cawndilla in NSW, which is part of the Darling River’s Menindee Lakes system near Broken Hill, earlier this month.

The area is an important bird and fish habitat in the Kingchega National Park that attracts rare waterbirds such as brolgas, water fowls, freckled and blue-billed ducks, about 1070km west of Sydney, according to the NSW National Parks and Wildlife Service.

Authorities found there was no evidence of H5 bird flu in any of the the samples that were tested, and it was not possible to further investigate the pelicans’ deaths because of the state of their carcasses.

It is possible the mass deaths were caused by botulism, a fatal disease in waterbirds, which can occur when a neurotoxin from a bacteria in the water is ingested.

The bacteria can develop when oxygen levels are low, water temperatures are high or decaying matter is in the water.

Mr Cook said he was “pretty shocked” to find 400 dead pelicans at the lake.

“It didn’t come back as bird flu, but I think it’s quite hard to get a positive identification if the birds have been dead for a while,” he said.

“Bird flu or not, it was still pretty shocking to find there.”

Mr Cook said it was not unusual for pelicans and other rookeries to die in large numbers when their food sources ran out.

He said when parents could not feed their chicks through fledging, younger birds could not fly off with their parents and perished.

“That sometimes happens at Lake Eyre, and it happened last year at Cawndilla, but it didn’t seem to be the case because there was still lots of healthy pelicans,” he said.

“There were young pelicans that had just made it through and were obviously fledged and hanging out with the adults, and there were still lots of other lots of other fish-eating birds.

“I even found a few, little fish called bony bream in in the lake there.”

Mr Cook said Lake Cawndilla was fairly remote so it was unlikely the pelicans died from pollution or toxins.

“Perhaps another disease, although other birds at the wetland seemed healthy,” he said.

Authorities urged members of the public to continue reporting unusual events such as multiple dead birds, sick bird or significant increases in mortality.