In the past penguins around the world have been:
- Slaughtered for oil
- Their skins turned into golf clubs
- Eggs and meat eaten
- Used as fish bait
In New Zealand the yellow-eyed penguin (Hoiho) evolved in the cool coastal forest of New Zealand where it had no natural enemies. With the arrival of humans came firstly the kiore (Polynesian rat) and dogs. Later the Norway and ship rats, cats, cattle and sheep arrived. The coastal forest that was home to the yellow-eyed penguin was burnt down or cut to clear the land for farming cattle and sheep.
Predators such as mustelids (stoats, ferrets and weasels) and feral cats are one of the worst threats to the yellow-eyed penguin populations. Rabbits were brought over from Europe as pets and for sport. They thrived on the new pastureland so it was decided to introduce ferrets, stoats and weasels to control rabbit numbers. Although these predators had a plentiful food supply in the rabbits, the numbers of rabbits continued to increase. What’s more, native birds including Hoiho and its chicks became easy prey for these introduced predators.
New Zealand doesn’t have these predators naturally so for years the penguin had no need to develop defences against them. When people introduced predators, the penguins had no method of defending themselves.
Recently Hoiho has been faced with another threat in the form of a shortage of their food supply from the sea. One factor causing these shortages is the warmer water temperatures as a result of the El Nino/La Nina weather pattern (the Southern Oscillation, an unusual climatic pattern which leads to lack of nutrients in coastal surface waters and reduced numbers of fish).