Bird experts cover 38,000km looking for signs of H5 bird flu

The annual aerial eastern Australian waterbird survey has not identified an impact from bird flu.

Researchers flew 38,000 kilometres across a third of the continent, including more than 1,000 wetlands, for the count.

Ecologist Richard Kingsford says it's "a matter of time" before more bird mortalities are recorded.

Every year ecologist Richard Kingsford takes to the skies, and counts birds.

He describes it as something like a race call, spoken into a dictaphone.

"We count them in packages of tens, fifties, hundreds, sometimes even thousands and as you can imagine there's more than 50 different water bird species that we're identifying so it's pretty taxing, particularly where you've got a lot of birds on a wetland."

Researchers fly at low levels across wetlands and rivers conduct the race call count for the annual eastern waterbird survey, covering 38,000 kilometres across about a third of the continent.

The University of New South Wales study, supported by the Queensland, New South Wales, Victorian and South Australian governments, has been going for 44 years.

Professor Kingsford has been on board for almost all of the counts, and said over the decades he had seen a 60 to 70 per cent decline in bird populations.

"We've put that down to the major changes that happened in the Murray Darling, particularly the diversion of water which meant that those wetlands, which birds breed in, weren't getting the floods they used to get," he said.

Professor Kingsford said populations had stabilised in more recent years due to higher rainfall from La Niña weather patterns, and the returns of some environmental flows to river systems.

But the birds now face another big threat — the spread of H5 bird flu into Australia.

Professor Kingsford said the survey was uniquely equipped to monitor that threat.

"Because we're surveying something between a thousand and two thousand wetlands, more than 50 water bird species and we know bird flu is going to impact them more than anything else."

When bird flu reached Australian shores in June, the researchers developed a protocol for reporting any bird deaths they see.

They have not observed an impact from bird flu.

Professor Kingsford said hundreds of dead pelicans had been seen inland, around the Kati Thanda-Lake Eyre region, but those deaths were likely a normal part of a boom and bust breeding season.

"So we've probably got a few hundred pelicans that have died, nothing to indicate anything like bird flu because you don't see any sick birds, you also see these pelicans with other birds like straw necked ibis and they all seem to be fine but what it is showing us is we've got a good way of measuring whether we've got a bird flu incident."

The survey's observations matched those of scientist Vidya Bhardwaj from the CSIRO's Australian Centre for Disease Preparedness.

She said outbreaks of H5 bird flu so far appeared to be largely confined to Australia's coastline, and even those cases had slowed down.

But while initial dire predictions had not eventuated, Dr Bhardwaj said the disease had not gone away.

"It's arrived, it's in our wild bird population so we now have a situation of coastal smouldering avian influenza," she said.

"What we do know is that avian influenza virus survives for a much shorter period of time in hot conditions than it does in cool wet conditions so coming into summer you would expect that there is less around.

"What it will look like when the season changes again or even during summer is really hard to predict."

Professor Kingsford said numbers of birds in some wetlands had not been as high as he might have expected, but that could be due to the amount of water still present inland from major flooding events.

"There's still quite a lot of birds spread out, we've had a couple of really big boom years," he said.

One of the last legs of the survey was along South Australia's Coorong, a wetland considered internationally important for migratory birds.

"We only saw a few hundred and I think what's happening there is there's a lot of habitat in central Australia so we've got the water birds quite spread out at the moment."

Professor Kingsford said as the inland waters dry out, those populations would become more concentrated, but that created its own risk.

He expected it was only a matter of time before he would be counting the toll of bird flu in his annual survey.

"All we can go on is what's happened overseas and it's been devastating there," he said.

"Many rookeries have had huge impacts like 50 per cent loss.

"Because we haven't seen many this year doesn't mean it's not there.

"It's coming, it will spread, it's inevitable and I think over this next year or so we'll start to see that, a lot more bird deaths and as they spread throughout the water bird community."