When an organism molts, it sheds its skin, feathers, hair or shell. Different creatures molt for different reasons but if one molts, the process is part of its regular life cycle, not a catastrophic event.
Crabs molt in order to grow. A crab sheds its rigid shell and grows quickly while its new, soft shell is still flexible enough to expand in. Once the crab’s new shell hardens, the crab stops growing. The crab will need to molt again in order to grow again. Dragonfly nymphs are another example of organisms who molt in order to grow.
Birds molt for different reasons. When the nesting season is over and it is time to fly south for the winter, a migratory bird needs new, undamaged feathers for its long journey. It therefore molts. The bird’s old, worn-out feathers fall out and new feathers grow in their place.
Many birds also molt in the spring. Some male birds shed their regular plumage for fancy, mate-attracting plumage to wear during the breeding season.
NuNu has drawn a male scarlet tanager three times for this week’s post. On the left you can see the bird wearing his breeding plumage, which is bright red. In the center you can see his mottled, half-scarlet, half-yellow, mid-molt plumage. On the right you see him in his brownish-yellow basic plumage. The scarlet tanager will molt again in the spring before the breeding season and his feathers will once again be a lovely scarlet color.