Native to New Zealand, these birds may be the most ancient of all living penguins, and they live long lives, with some individuals reaching 20 years of age. Habitat destruction, introduced predators and disease have caused the penguins' numbers to drop to an estimated population of 4,000. In 2004, a disease linked to a genus of bacteria that causes diphtheria in humans wiped out 60 percent of the yellow-eyed penguins chicks on the Otago Peninsula. And a new study published in the journal PeerJ shows that breeding penguins declined by 76 percent between 1996 and 2015. The species is endangered and may go locally extinct by 2043, according to the study.
The yellow-eyed penguin, or Hoiho, appears on the New Zealand $5 note.