The Otago Daily Times has been informed of the deaths of the tītī, also known as the sooty shearwater, and was told the Department of Conservation and the Ministry for Primary Industries (MPI) are looking into the matter.
An MPI spokesman said Biosecurity New Zealand’s main role in this event was to determine whether an exotic (introduced) disease was involved in the death of the birds.
"We are in the process of testing samples from the island but we have been able to eliminate high pathogenicity avian influenza as a possible cause.
"Although the current event is larger than those we usually see, large numbers of bird deaths are not uncommon. In many cases, botulism or toxic algal bloom was found to be the cause. Other causes of seabirds deaths we have investigated indicate that starvation and storm-associated events are possible causes for this event."
The birds breed on numerous islands around New Zealand, from the Three Kings in the north to islands around Stewart Island, as well as The Snares, Auckland, Campbell, Antipodes and Chatham Islands.
A few small colonies persist on headlands of mainland South Island, but all the large colonies are around Stewart Island or on The Snares.
Doc operations manager Jennifer Ross said if people came across starving or stranded tītī, their advice was to leave them alone unless they could be sent to a rehabilitation centre.
"Anecdotally, we're hearing it has been a very poor season for tītī as part of the annual cultural harvest. Unfortunately, mass mortality events or ‘wrecks’ are not uncommon in many migratory sea bird species.
"Weather, starvation and exhaustion can all play a role in these events, and historically, El Nino weather patterns tend to have worse outcomes for tītī. At this time of year, the young tītī are fledging the nest and a combination of poor weather, starvation and inexperience flying could be a factor."
Avian flu has been spreading globally since December 2021 but has not been detected in New Zealand, Australia, the Pacific Islands.
New Zealand has never had a case of Avian flu, but low-pathogenicity avian influenza viruses have been detected through surveillance in wild mallard ducks in the past.
Use of Avian flu vaccines in New Zealand is prohibited. However, the MPI has granted approval for Doc to use this vaccine in a controlled trial to test its safety and efficacy in some endangered native birds.
University of Otago microbiology and immunology lecturer Prof Jemma Geoghegan said should Avian flu be detected in the future, the effect could be potentially devastating for many of the country’s endangered birds.
Prof Geoghegan said the mutations of Avian flu over the past decade meant it could infect a much broader range of species.
"It’s becoming more concerning; as it is now spreading to mammalian species."
