Tragically, many dead yellow-eyed penguin adults were found on Otago Peninsula beaches and in breeding areas from mid January to the peak in early February 2013. By 8 February, 25 adult yellow-eyed penguins had been found dead. By 15 February the total had risen to 56, all of which were sent to Massey University for examination.
Yellow-eyed penguins in the Catlins and North Otago have not been affected, nor other sea birds and marine mammals.
Early suspicions that heat stress was the cause of death were discounted, and by 4 February a bio-toxin of some kind was suspected. As of 7 March, toxicology results are so far inconclusive, but more tests are being carried out. Although some other agent such as a virus or bacteria may be involved, the Massey vets still think it is some kind of marine bio-toxin.
Trust staff and volunteers checked the Yellow-eyed Penguin Trust Reserves of Okia and Otapahi during the weekend of 16 and 17 February. To the Trust’s relief, no further dead yellow-eyed penguins were found.
Checks, however, continued over the following weeks so that any chicks found could be weighed and, if underweight, taken to the hospital at Penguin Place for feeding to reach a reasonable fledging weight. While many chicks have fledged and gone to sea, some are still in the vicinity of their nest sites and may be losing weight, especially if one or both parents have died.
Since the peak of the adult penguin mortality, only two freshly dead adults have been found – on 19 February and 3 March – bringing the total of dead adults to between 60 and 65. Further beach and breeding area monitoring is ongoing.