Unlike most other seabirds, penguins undergo an annual catastrophic moult where they lose and replace all of their feathers at once.
The moult takes 3 to 4 weeks and typically begins in February for juveniles and March/April for adults.
During the moult, because plumage is not waterproof and the body is not well insulated, they cannot go to sea to feed, and may lose 3 to 4 kg in weight.
They are confined to shore as they wait for their old feather coat to be replaced. This is a very stressful time for birds – energy levels are low, there is threat of starvation and dehydration, and they are unable to escape easily from predators.
Penguins are particularly scruffy and can sometimes look sick during the moult. Please contact the DOC helpline on 0800 DOCHOT if you are worried about a bird.