Scientists discover why 3 million shearwater birds washed up on Australia's east coast in 2013


A chance encounter between two very different scientists has solved the mystery of why three million dead birds washed up on the Australian east coast eight years ago.

There was a mass fatality of short-tailed shearwater birds in 2013, which researchers have now discovered was caused by starving birds eating volcanic rock and plastic out of desperation. 

CSIRO scientist Lauren Roman, a researcher on plastic congestion in seabirds, said it was an odd coincidence the hundreds of ocean birds that washed up on a beach right next to her research station were full of pumice.  

‘Very close to the research station where I was working at the time, there was more than 100 birds dead and dying … along every kilometre of this very, very long beach,’ she told Daily Mail Australia.

Working at Moreton Bay Research centre at the time on North Stradbroke Island, Ms Roman recruited science students to collect the birds and put them in a freezer to look at later.

Researchers found dead birds washed up on the Australian east coast eight years ago

Researchers found dead birds washed up on the Australian east coast eight years ago

After a few weeks, she realised the dramatic mass death wasn’t just happening in her backyard, but across thousands of kilometres on Australia’s the east coast, from  Fraser Island up north to Tasmania down south.

Even more unusual was what researchers found inside the birds when they conducted auto-necropsies – four or five pumice stones, which are floating aerated volcanic rocks.

‘Occasionally you do find a pumice stone or two in a seabird, but you don’t often find many of them. And they don’t find them in the stomachs of just about every single bird,’ said Ms Roman.

There mass fatality of 3 million short-tailed shearwater birds in 2013 (pictured)

There mass fatality of 3 million short-tailed shearwater birds in 2013 (pictured)

The shocking discovery raised more questions than answers, especially because veterinary autopsies showed the birds were in bad condition and possibly starved to death.  

There was no way Ms Roman could solve the riddle on her own, but another coincidence connected her with just the expert she needed.

One of the students enlisted to collect the birds with Ms Roman had Scott Bryan as her supervisor – who just happened to be an expert in pumice rafts, which are mass floating rocks on the ocean after volcanic eruptions.

The birds were found to be full of pumice, a volcanic rock (pictured), stunning researchers

The birds were found to be full of pumice, a volcanic rock (pictured), stunning researchers 

‘Scott and I were each from very different disciplines … you wouldn’t find us in the same building together or talking to each other,’ said Ms Roman. 

‘But neither of us would have been able to solve this mystery without the expertise of the other.’

In a team that included Dr Kathy Townsend, Dr Natalie Bool and the then-third year student who connected the two researchers, Leah Gustafson, a question was formulated.

Did the birds die because they ate the volcanic rock, or did they eat it because they were starving?

An eight year investigation into the mystery uncovered where the rock came from

An eight year investigation into the mystery uncovered where the rock came from

First the group would have to work out where these birds had been – luckily for Ms Roman, a woman she sat next to as a student had spent years tracking the migrating patterns of this particular bird species, which was consistent each year.  

Next, Mr Bryan and Ms Gustafson had to identify the rocks origins, and they used satellite systems to discover it was from the 2012 Havre eruption in the Kermadec arc north of New Zealand. 

Usually the ocean birds would feast in the Artic circle before migrating for ten days to the southern hemisphere, where they would breed in Victoria or Tasmania, and occasionally even as far down as Antarctica.  

‘We realised that the birds could have only interacted with that pumice in the few days before that they died,’ said Ms Roman.

‘So they must have been already in very bad condition and already very, very hungry at the time that they interacted with the with the pumice raft.

‘If they were in fat condition, they just would have flown straight past that. They wouldn’t have stopped to try and sort of feed in desperation because they would otherwise have no reason to stop.’

Researchers concluded the birds ate the pumice (pictured) because they were starving

Researchers concluded the birds ate the pumice (pictured) because they were starving

The next step for the researchers is to determine why the birds were starving.

They believe it is likely they became famished in the northern hemisphere. 

One possible explanation is that a marine heat wave up north from 2013 to 2016 – called the Blob – decimated the species the shearwater feeds on. 

Another is that because the bird species and pink salmon – which is artificially reared and released – feast on the same food, the fish could have stolen all the shearwater’s usual prey. 

The next step for scientists is to work out why the birds were starving

The next step for scientists is to work out why the birds were starving  

Ms Roman is hoping to receive grant money to continue the quest to solve the puzzle, and she predicts climate change might be affecting the birds.

‘Climate change is a serious threat to many different see bird species,’ she said. 

‘But it’s something that’s quite hard to research because you’re looking at changes to a bird that’s very, very hard to find. 

‘They’re out. They live out in the middle of the sea. It’s very hard to know what’s killing them when they start disappearing again because they live out in the middle of the ocean.’

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