Habitat degradation is ongoing in the South Island, but has been curtailed to a significant extent. Introduced ferret Mustela furo, stoat M. erminea and cats are major predators in the South Island and on Stewart Island, as demonstrated by the paucity of juveniles there¹⁵. Predators are also present in all main breeding colonies on the islands (except Campbell Island), but their impact is unknown³. Rogue female Hooker's sea lions eat 20-30 birds annually on the Otago Peninsula¹³. Population crashes may be due to avian malaria or biotoxins¹⁴, and food shortages due to sea temperature changes may also be a periodic problem⁷. Disease appears to be a major problem in some populations with diptheritic stomatisis (caused by the bacteria Corynebacterium amycolatum) and a Leucocytozoon blood parasite (formerly only known from Fiordland penguins) major causes of mortality for chicks^17,18. Human disturbance, even from tourists at breeding colonies, negatively affects fledgling weight and probability of survival¹¹. Drowning in fishing nets and accidental fires are additional known threats⁵.