The Fiordland crested penguin has declined in numbers drastically during the last twenty years. In the 1980s, the global population was estimated to number 10,000 breeding pairs. Today, the number is thought to be 2,500 to 3,000 pairs. The principal cause is believed to be from introduced animals such as cats and stoats (5), although where the birds’ breeding sites are close to public beaches, pet dogs are thought to be largely responsible for disturbing adult birds and catching chicks. With the increase in human leisure activities, this pressure is bound to intensify (2). There is also a problem with the endemic weka, Gallirallus australis, which preys on eggs and chicks and is thought to contribute to over a third of egg loses in some breeding areas, especially Solander Island (5).
At sea, penguins are in constant competition for food with fishing vessels and sometimes find themselves caught in fishing nets. Perhaps the biggest threat, however, is through marine pollution, particularly oil spillage and the illegal but common practice of discharging oil tanker ballast water off-shore (5). As yet, little is known about the possible effects of global warming on penguin populations (5).