An outbreak of avian cholera on the Coorong has claimed the lives of between 800 and 1,000 birds since late January, with a local ecologist concerned that it has the potential to spread to endangered ospreys and other raptors in the area.

Warning: Some readers may find images in this article disturbing.

A South Australian Department for Primary Industries and Regions spokesperson said the government was monitoring the situation in partnership with the Department for the Environment and Water and while the disease was not considered to be high risk for humans, all contact with sick, dying, or dead birds should be avoided.

Coorong fisherman Garry Hera-Singh said he originally noticed two or three dead ducks a day in late January.

But he said he was soon seeing as many as 10 washing up on the shorelines of Pelican Point and the sandbars at Ewe Island.

Garry Hera-Singh says he has been fishing on the Coorong for decades.(ABC South East SA: Caroline Horn)

Mr Hera-Singh said he collected 11 fresh specimens and delivered them to biosecurity officers.

Testing confirmed the presence of Avian pasteurellosis, commonly known as avian cholera or fowl cholera.

A primary industries spokesperson said between 800 and 1,000 bird deaths had been reported, with about 100,000 live waterbirds thought to be in the area.

They said the majority of deaths had been reported in grey teal, hardhead, mountain, and black ducks as well as cormorants, grebes, seagulls, and black swans.

A decaying cormorant lies on the ground at Pelican Point.(ABC South East SA: Caroline Horn)

Outbreak area

Mr Hera-Singh, who has fished on the Coorong for 40 years, said it was the first outbreak of the disease in the area he had seen.

He said the outbreak appeared to have affected a small area around Tauwitcherie and Ewe Island.

The deaths are occurring between Mark Point and Pelican Point.(ABC South East SA: Caroline Horn)

“It’s most unusual, and I’ve been well south of Tauwitcherie looking for dead waterfowl and can’t find anything, particularly in the Long Point, Seven Mile Basin, no dead birds at all and yet every time I come back to Pelican Point you start seeing them straight away,” he said.

He was concerned the disease could be affecting rarer birds feeding on infected or dead birds.

That’s really a concern, a long-term concern because a lot of these birds are in low numbers anyway,” he said.

The outbreak has affected a range of ducks and other waterbirds.(ABC South East SA: Caroline Horn)

What is avian cholera?

University of Queensland Avian and Exotic Pet Service head Bob Doneley said avian cholera was a “nasty” respiratory infection.

Professor Doneley said it was unusual for it to be found in wild birds and was often spread by rodents or directly from bird to bird, including when birds feasted on others that had died from the disease.

Grey teal ducks are among the birds that have been affected.(ABC South East SA: Caroline Horn)

“It can be found in any species of bird,” he said.

“Most typically when I see it, it’s in chickens.”

Professor Doneley said the disease had a high mortality rate and symptoms could include swollen heads, swollen combs and sinuses, sneezing and coughing.

He said it could then become septicaemic and then affect the lining of the heart, leading to sudden death.

What causes an outbreak?

Adelaide University School of Animal and Veterinary Science researcher Darren Trott said newly published research indicated the strains of avian cholera found in wild birds in Australia were very similar, but not identical, to those that caused the same disease in caged or free-laying poultry.

Professor Trott said it was likely that a bird carrying the infection had come to the Coorong and spread the disease, with high-density numbers needed for disease transmission.

“It’s hard to put your finger on why you get these outbreaks in populations but usually it’s a number of factors combining together with a carrier animal bringing it in,” he said.

Professor Trott said the data gathered by primary industries from the specimens collected by Mr Hera-Singh would be of great interest to researchers.

He said the disease had been recorded in raptors in the past, albeit rarely.

Mr Hera-Singh’s concerns for the Coorong’s ospreys and other raptors were shared by ecologist Faith Coleman, who works in the Coorong’s South Lagoon.

Ms Coleman said she went to Pelican Point in late January after hearing of the outbreak.

She said she documented 100 dead birds along the shoreline on that visit.

“What I also saw when I was there was a lot of the raptors eating them and that deeply concerns me,” she said.

Faith Coleman is concerned the outbreak could spread to ospreys and other raptors.(Supplied: Faith Coleman)

Ospreys are endangered in South Australia.

A recovery plan is in place to try to revive the population, which is thought to number less than 50 breeding pairs.

Ms Coleman said she had also seen a number of dead magpie larks.

She investigated their gut contents and found their stomachs to be full of maggots, which she believed were most likely removed from the decaying ducks nearby.

Faith Coleman is concerned that magpie larks may be falling victim to the disease.(ABC South East SA: Caroline Horn)

“Magpie larks are really common; they’re everywhere but it just tells you how far a disease is spreading when you start seeing it with our little resilient magpie larks dying,” Ms Coleman said.

Managing the outbreak

Ms Coleman said she asked biosecurity officers what the plan was to manage the outbreak.

“I went to them to ask why it would be there and what we can do about it and what I got was an identification of the disease but no actual on-grounds action, which was a little frustrating,” she said.

“My concern is that we’re leaving the corpses to lie there, and the bacteria may persist for another year — and that’s what we’re seeing overseas with these outbreaks — is that it persists through seasons, through survival in organic and aerobic sediments.”

Ms Coleman said she had asked primary industries whether it was possible for the carcasses to be collected to remove them from the environment and scavengers but had been told it was too big of a job.

“There’s a technical conversation to be had and I don’t believe it’s happening,” she said.

The department said the reported numbers of wild bird deaths had reduced in number naturally over time, but it remained alert to the situation.

The spokesperson said decomposition was a natural part of the environment and any concerns about the amenity of the area should be raised with the local council.

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