Most penguins live in big noisy colonies, all crammed together. The yellow-eyed penguin is different. It likes its space. Pairs nest by themselves, often hidden in coastal forest, where they cannot even see each other. Scientists call them the world's 'shyest' penguins.
They are also surprisingly tall. A yellow-eyed penguin stands about 65 centimetres - around the height of a primary-school child's waist. Their walk on land is the classic penguin waddle, but in the water they shoot along at up to 25 km/h, chasing small fish.
Each penguin has a slightly different yellow pattern around its eyes, like a special mask. The colour is brightest in adults. Younger penguins have paler eye markings until they grow up. Scientists who study them can tell individual birds apart by their faces - a bit like school photo day at the colony.
Yellow-eyed penguins are protected very carefully in New Zealand. Some beaches close at dusk so the penguins can waddle out of the sea and home to their nests without being disturbed. Conservation rangers track the families and make sure they have safe places to nest, dry chicks and full bellies.