The yellow-eyed penguin chicks are being killed by a mystery illness. Photo: AFP The Ministry for Primary Industries (MPI) is involved in investigating the cause of the outbreak, which has affected the South Island's under-threat hoiho population. Wildlife experts say the new illness is a cause for concern as they battle to ensure the species' survival. Wildlife veterinarian and founder of the Dunedin Wildlife Hospital, Lisa Argilla, told Morning Report the disease was incurable. "The respiratory disease is too much, it pretty much demolishes their lungs," she said. "The post-mortems that I've done, about 58 of these chicks and most of them had this disease and it's incredible what their lungs look like."