Moulting
Biological process of shedding body parts for beneficial purposes.
Moulting (or molting), also known as sloughing, shedding, or ecdysis in many invertebrates, is a biological process by which an animal casts off parts of its body for beneficial purposes, either at specific times of the year or at specific points in its life cycle. In medieval times, it was called 'mewing' (from the French verb 'muer', to moult), a term that survives in the name of Britain's Royal Mews, where the King's hawks were kept during moulting before becoming horse stables after Tudor times.
- process
- Shedding of epidermis, pelage, or exoskeleton
- occurrence
- Birds, reptiles, amphibians, arthropods, dogs, guinea pigs, hamsters, rabbits
- bird frequency
- At least once a year; many moult twice, a few three times
- dog frequency
- Twice each year (spring and autumn)
- forced moulting
- Used in commercial layer hens to reinvigorate egg-laying
- medieval term
- Mewing (from French 'muer')
Lore & Background
Moulting can involve shedding the epidermis, pelage (hair, feathers, fur, wool), or other external layers. In some groups, entire exoskeletons are shed, including wings in some insects. In birds, moulting is the periodic replacement of feathers, which are dead structures at maturity that become abraded and need replacement. Adult birds moult at least once a year, though many moult twice and a few three times. The process is generally slow and symmetrical, with feather loss equal on each side of the body. Because feathers make up 4–12% of a bird's body weight, moulting requires significant energy, so it often occurs after the breeding season when food is still abundant.
Reader's Guide
Moulting is a fundamental biological process across diverse animal groups, enabling growth, repair, and adaptation. In birds, it ensures feather replacement for insulation, flight, and display, with timing linked to breeding and migration strategies. In reptiles and amphibians, moulting maintains skin health and vision, as seen in snakes shedding their skin in one piece including the brille. In arthropods, ecdysis permits metamorphosis and growth, with the new exoskeleton initially soft before hardening. Forced moulting in commercial poultry, involving food withdrawal or dietary manipulation, is a controversial practice to reinvigorate egg-laying. Understanding moult patterns aids in studying animal ecology, evolution, and welfare.
Did You Know?
- In medieval times, moulting was called 'mewing', from the French verb 'muer', and the term lives on in Britain's Royal Mews.
- Some birds become flightless during an annual wing moult and must seek protected habitats with reliable food supplies.
- In snakes, moulting involves rubbing the head against hard objects to split the skin, which is then turned inside-out as the snake crawls out.
- Forced moulting in commercial layer hens can involve complete food withdrawal for 7–14 days, causing 25–35% body weight loss.
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