Disease causing high mortality in yellow-eyed penguin chicks

In late November, several cases of avian diptheria (Corynebacterium) were confirmed in yellow-eyed penguin chicks at locations on the Otago Peninsula and North Otago. The disease results in lesions in the mouth and throat, causing respiratory problems and poisoning of young birds. Mortality rate of chicks is thought to be 60% or higher.

After further sampling, the epidemic was found to be more widespread than first thought. Aside from being present in every colony checked on the Otago Peninsula and North Otago, Yellow-eyed Penguin Trust staff discovered infected chicks at Sandy Bay in the Catlins. No other species are known to be affected.

Back on the Peninsula, the treatment of chicks with antibiotics is having mixed results, with some chicks dying and others recovering. Massey University scientists are working hard to identify the specific bacteria, which may give us some clues as to the source of the disease and its mode of transmission.

We are continuing to monitor the situation in the field and treating chicks where practical. PhD student Thomas Mattern (assisted by David Blair, Projects Officer for the Yellow-eyed Trust) has started deploying GPS loggers on adults from affected nests at Boulder Beach and will do some diet sampling. This will give us a picture of where the birds are foraging and on what, which may prove useful if the source or trigger of the infection is marine based.

Adult penguins remain unaffected, so tourists wishing to see penguins are still able to view them. However, tourism operators reliant on nests being viewed are affected, as the adult birds may not remain at the nest sites when the chicks have died. The adults can still be viewed as they go out to sea in the morning and return to land in the evening.