By Rebecca Fox on Mon, 3 Aug 2009
News: Dunedin | Conservation
Despite investigations by Massey University wildlife scientists, mystery still surrounds the cause of the skull deformities in endangered yellow-eyed penguins at Okia Reserve and the deaths of penguins from other Otago Peninsula beaches last summer.
Eight birds with skull deformities were found at the yellow-eyed penguin reserve at Okia during the past breeding season and many from the northern part of Otago Peninsula died in their nests.
The losses were variable across breeding sites; in some, 50% of chicks died.
Massey University was called in to help find the cause of the deaths and about 80 chicks were sent to the university's wildlife centre for autopsies.
At the annual Yellow-eyed Penguin Symposium held at University College on Saturday, the centre's researchers presented their findings.
Yellow-eyed Penguin Trust general manager Sue Murray said despite all the work, they still did not know the answers to what caused the deformities and deaths.
While the problem was in a very small number of birds, those managing them still needed to know the cause and whether it could have an impact on the rest of the ecosystem.
That took research, but she asked who would fund it.
Pathology resident Kelly Buckle said the eight birds with skull deformities, including a significantly shortened beak, from Okia were so profoundly affected they were not able to survive in the wild.
She did not believe the deformities were the result of genetics, diet or heat stress.
Toxicology results had ruled out heavy metals, but some results were still awaited.
"All signs point to a toxic point source exposure as all the birds were exposed at the same time, same place, to the same thing."
Veterinarian Lisa Argilla, presenting a paper by Avian and Wildlife Health senior lecturer Brett Gartrell, said large-scale nest deaths like last summer's had been reported before and it was important to look at all factors.
Postmortems on 53 chicks aged from 4 days to 17 days old, 44 from Otago Peninsula and nine from Oamaru, identified no single cause, but there was a high incidence of stomatitis, bacterial pneumonia and septicemia.
Associate Prof Maurice Alley said his investigations showed about 22% were affected by diptheritic stomatitis, which fluctuated in a biennial pattern.
About 15% died of starvation and a similar amount from respiratory disease.
"It's got to be an infectious disease . . . probably transported by insects."
The penguins suffered from lesions in the mouth which would have been painful and made them reluctant to eat.
As a result they suffered from pneumonia, and possibly ear infections, he said.
They were still looking for the primary cause, having ruled out as unlikely diseases such as avian pox and herpes virus.
University of Otago Associate Prof Michael Legge said given the hot summer experienced by Otago, high temperatures and UV radiation could be factors in the abnormalities.
Hen egg research had shown even slight fluctuations in egg temperatures could cause malformations and deaths.