Dr Janelle Wierenga came to Dunedin to look for what many expect to be a virus that leads to sores developing in very young chicks’ mouths, making eating and breathing difficult.
Known as diphtheritic stomatitis, or avian diphtheria, the disease is treatable, but undetected can kill birds before they reach 2 weeks old.
Over the course of the summer, when Department of Conservation rangers and others went to check on the nests of the endangered species, they found a raft of young chicks dying with blood and fluid in their lungs.
Dr Wierenga said she now hoped to at least narrow the scope in the search for the cause of this second illness devastating the youngest members of the species.
Researchers had known about avian diphtheria in yellow-eyed penguin chicks for a couple of decades now, she said.
But they only started seeing deaths from respiratory failure in 2019.
"And we were not sure whether we were going to see that this year or not, but we did see quite a few deaths."
Her two-year research project, a collaboration between Massey University and the University of Otago, used a "pathogen discovery approach".
And in the case of avian diphtheria, it could be used to identify the cause.
Avian diphtheria had been inconsistently linked with a bacteria, Dr Wierenga said.
But debate remained as to whether the bacteria was a primary cause or a secondary cause of the disease, she said.
"We’re going to look for viruses, bacteria, fungal organisms, protozoa, anything that could be causing it.
In the case of the respiratory disease, there was more work to do, and at this stage her work was more a matter of ruling pathogens out, rather than detecting them, she said.
Yellow-eyed penguins (also known as hoiho) have been moving towards extinction on mainland New Zealand for years.
Some of those most familiar with the birds say they will be gone from the South Island’s coast before the middle of the century.
Department of Conservation acting Dunedin operations manager Craig Wilson said the research being done by Dr Wierenga was essential work.
Conservation management of yellow-eyed penguins (hoiho) at sea and on land was complex, he said.
Understanding and dealing with different types of diseases, the vectors that caused them, environmental factors that might exacerbate them, and how they affected different life stages of hoiho added to the complexity of keeping the species surviving.
This year’s breeding season had started poorly with one of the lowest ever number of nests recorded, he said.
Diphtheritic stomatitis was prevalent throughout the mainland hoiho chick population, but the treatment plan in place had worked well and survival rates improved.
However, the unknown respiratory disease was also common and took a toll, Mr Wilson said.
"The majority of chicks that made it through those early critical weeks have gone on to be healthy and heavy with some record weights recorded throughout the season; this is probably due to a good food supply at sea."
Chicks were now starting to fledge, he said.
