The number of little penguins being found dead along South Australia's South Coast over the summer has raised concerns for local volunteers and researchers.
Researcher Stephen Hedges has collected the remains of eight penguins over a three-week period.
He said he would normally expect to be notified of one dead little penguin a week on average.
The spate of deaths has coincided with the floodwaters from the Murray River entering Encounter Bay.
The floodwaters have made the marine environment murky, and have result in a die-off of sea cucumbers and other bottom-feeding marine species.
Millions of juvenile carp have also been flushed into the seawater and the remains have been deposited on local beaches.
Mr Hedges said three of the eight birds found were whole specimens and "very fat".
"These are the fattest birds I've picked up in the past 10 years," he said.
"One weighed as much as 1.4 kilograms when 1kg is average for a little penguin."
Mr Hedges said one of the penguins found had new, very blue feathers, indicating it may just have finished moulting.
Penguins moult for about three weeks and during this time will not go to sea or feed.
Mr Hedges said while it was not yet known whether the deaths were linked to the floodwaters coming out of the Murray River, the increase in dead penguins has raised questions.
"Until we can get them tested it's hard for me to guess but it is unusual, if I can put it that way, to have very fat birds that have died and look in a whole, healthy condition when we find them.
"They look well-fed.
"The two things are happening at once, so we'll have to wait and see."
Mr Hedges has been involved with monitoring the little penguins that come ashore at Granite Island for nearly 30 years and has seen their numbers decline from more than 1,500 in 2001 to an estimated 22 today.
He said he was frustrated that the survey information relating to penguin numbers in the area was outdated.
"We don't know what the base number is," he said, adding that this made it impossible to know whether the number of animals being found now was indeed a significant percentage of the remaining population.
He has called many times for a curfew on tourist visitors to the island from dusk to dawn, particularly during the breeding and moulting season from spring to January to try and help the population to recover.
"In my opinion these are some of the most stressed penguins in the world, due to human disturbance," he said.
"Since the new causeway opened it's often busier than the Adelaide Oval bridge."
Ikuko Tomo is an honorary research associate with the SA Museum and has carried out many of the necropsies on little penguins found in the past.
She said while she has not yet seen the recently collected remains photographs indicated that the penguins were in good condition and likely experienced a quick death.
She said the lack of funding to support little penguin research made it difficult to understand what was happening when there was a cluster of deaths.
"We need to know what is usual, to quickly identify when things become unusual."
A Department for the Environment and Water spokesperson said a ranger has collected the remains and testing would be conducted to try to ascertain a cause of death for the birds.
The spokesperson said the department was not considering implementing a curfew and that an improved fox gate was preventing foxes from getting to the Island and protecting the penguin population.
Nine little penguins were killed in a fox attack on the Island in June 2020 and since then the department has also used electronic fox deterrents and baits when necessary.
A draft Granite Island Recreation Park Visitor Experience Plan was released for public consultation in 2021 but a final plan has not yet been released.
The spokesperson said it expected the final plan to be available in the first half of 2023.
Flinders University researcher Diane Colombelli-Negrel said she also supported the call for a curfew on Granite Island during the breeding season to protect the remaining little penguin population.
"We must provide a safe place on land for them," she said.
Dr Colombelli-Negrel said there had been a small but very slow increase in little penguin numbers since the 2020 fox attack.
"We are hoping this will continue."
She agreed there was a shortage in funding for research into the penguins.
"For example, what they eat is a big missing gap in our knowledge," she said.
Dr Colombelli-Negrel's past research has indicated that the Millennium drought and lack of Murray River flows into Encounter Bay had a detrimental affect on the colony.
She hopes that the floodwaters entering Encounter Bay will eventually have a positive effect on penguin numbers.
In the meantime, Mr Hedges and his band of volunteers will keep watch.
Each night the volunteers come to what they jokingly refer to their office; a fenced-off area shared with bins from the local cafe, that serves as a storage area for their forms, torches and high-vis jackets.
Researchers said despite the fall in penguin numbers and the stress the birds face from interactions with tourists, the were hopeful the colony would survive.
"They keep hanging on," Mr Hedges said. "Despite everything."
