Moulting
Definition
Moulting is the annual process in which penguins shed and replace all of their feathers over a period of two to four weeks. Unlike most birds, which moult gradually, penguins undergo a catastrophic moult in which all old feathers are pushed out simultaneously by new growth. During this period, penguins cannot enter the water because they lack waterproofing, so they must fast on land. Penguins gorge on food beforehand, building up fat reserves to sustain them through the moult. A failed moult can leave a penguin with patchy plumage and compromised insulation.
Related Terms
The preening gland (uropygial gland) is an oil-producing gland located at the base of a penguin's tail.
Down feathers form a dense, insulating underlayer beneath the outer contour feathers of a penguin.
A fledgling is a young penguin that has replaced its downy chick plumage with waterproof juvenile feathers and is ready to leave the colony for the sea.
Frequently Asked Questions
What does moulting mean in penguin biology?
Moulting is the annual process in which penguins shed and replace all of their feathers over a period of two to four weeks. Unlike most birds, which moult gradually, penguins undergo a catastrophic moult in which all old feathers are pushed out simultaneously by new growth. During this period, penguins cannot enter the water because they lack waterproofing, so they must fast on land. Penguins gorge on food beforehand, building up fat reserves to sustain them through the moult. A failed moult can leave a penguin with patchy plumage and compromised insulation.
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Glossary entries define the language. FAQ answers common questions; guides carry the longer Survival Lab arguments.
More in reproductionWhere this definition comes from
Reference bodies behind the reproduction terminology. Links last checked August 5, 2026.
- British Antarctic Survey - Antarctic penguin ecology, diving, and sea-ice context.
- Australian Antarctic Division - Antarctic species profiles, breeding, and environmental context.
- Smithsonian Ocean Portal - Penguin biology, anatomy, and breeding explainers.