In the wild, Yellow-Eyed Penguins behave like other mobs. They only spawn on islands or coasts. When attacked, all other Yellow-Eyed Penguins around will get mad and attack you. Their call lengths vary based on their health.
When right-clicking any Yellow-Eyed Penguin with a raw fish, there is a 1/3 chance it will be tamed, even if it is angry. Tamed penguins wear red bow ties. You can shear a tamed Yellow-Eyed Penguin by right-clicking it with shears in your hand. There is an 80% chance it will drop brown or yellow Penguin Feathers, but a 20% chance it will become angry and attack; however, other penguins will not attack you in this situation. Note that tame penguins can be bred with wheat.
Yellow-Eyed Penguins will drop 0-2 brown Penguin Skins on death.