Molting penguin at the Kansas City Zoo.

All birds molt, or periodically replace their feathers by shedding the old ones and producing new ones.  Unlike most birds that molt a few feathers at a time, once a year penguins experience what’s called a catastrophic molt.  This means that they molt all of their feathers at once, making them look a bit like an exploding pillow.

Penguins go through a three stage molting process:

• Stage 1.  As the new feathers start to generate, the penguin stuffs himself with fish to pack on some extra pounds for Stage 2.
• Stage 2.  Because a penguin is not waterproof without feathers, he stays on land for about two weeks during this stage.  Because he’s not able to eat fish, he fasts during this time, living off the extra body weight gained in Stage 1.
• Stage 3.  This is the end of the molting period, and the penguin returns to the ocean to eat and enjoy his new feather coat.