An investigation of the causes of mortality in yellow-eyed penguins (Megadyptes antipodes) across their range with specific emphasis on the role played by Leucocytozoon : a thesis presented in partial fulfilment of the requirements for the degree of Master of Veterinary Science in Wildlife Health at Massey University, Palmerston North, New Zealand

Abstract

Over the past 40 years, there have been frequent mass mortality events documented in yellow-eyed penguins (Megadyptes antipodes). In most cases, these mortality events have resulted in significant adult or chick mortality resulting in a population decline. Previous studies in yellow-eyed penguin mortality have been attributed to events such as unidentified phytotoxins, starvation, poor nutrition, climatic events and infectious causes. However, the full impact of these factors on yellow-eyed penguin population decline and mortality events is not well understood. During the Austral summer of 2008/09, there were mortality events documented in both the subantarctic and mainland yellow-eyed penguin populations with different patterns of mortality and different factors associated with the mortality between both locations. A high overall prevalence of Leucocytozoon spp. in association with a high incidence of chick mortality was observed during this period on Enderby Island. Despite its endemic nature in this population, statistical analysis demonstrated that infection with Leucocytozoon did not play a significant role in mass mortality of Enderby Island chicks, other than as a cause of sporadic individual mortality. The Leucocytozoon spp. sequences detected lead to the conclusion that the Leucocytozoon parasite is endemic in yellow-eyed penguins and has a higher prevalence in penguins from Enderby Island than those from Campbell Island and the mainland of New Zealand. The Enderby Island yellow-eyed penguins are infected with a Leucocytozoon spp. that is genetically distinct from that found in other yellow-eyed penguin populations. The role of Leucocytozoon in the high levels of chick mortality in the yellow-eyed penguins remains unclear. A very low mortality was observed in the Catlins population despite there being a high level of human impact at some nest regions within this location. A high level of mortality was described in the Otago Peninsula population with this population affected by high human disturbance from tourism, reduced quality of breeding habitat, diphtheritic stomatitis as well as increased environmental temperatures during the study season. All of these factors played a significant role in mortality of chicks at this location. Results from this research provide the foundation for future investigations into the risk factors for mortality in yellow-eyed penguins across their range as well as providing a basis for sound management and veterinary advice to assist with conservation of this endangered species.