Molting: What Is It and What Animals Do It?

Molting.  That is such a weird word.  I have heard it or read about it many times.  For example, once I heard a park ranger use it when talking about birds.  But, I never really knew what it meant.  

molting, mountain goat

A molting mountain goat is shedding its thick winter coat.

What is Molting?

The dictionary definition of molting is – to shed the feathers, skin or like that will be replaced by new growth.

Or another definition states – the process of shedding an external skeleton for the purpose of growth or change in shape (such as what happens during metamorphosis).

I like to think of it as an animal getting rid of part of its body and replacing it with something new.  This could be feathers, skin, or even fur.

What Animals Molt?

The different kinds of animals that molt include birds, insects, reptiles, and even mammals.

Why Do Animals Molt?

Different animals molt for different reasons.  Some do it in order to allow them to grow bigger.  Others molt in order to look good so that they can attract a mate.  Some animals molt because they need to get rid of their thick winter coat that allowed them to survive the winter.  Here are some of the main reasons that the different kinds of animals molt:

molting, cardinal, bird

A molting cardinal.

Birds – Birds molt their old feathers in order to grow new, healthy feathers.  The new feathers will often be a different color than the old ones.  Birds will molt most or all of their feathers at different times during their life or during the year.  The new feathers that birds grow will indicate a different age, sex, or time of year.

At certain times of year, during mating season, birds will grow brightly colored feathers in order to attract a mate.  This is like a person putting on their fanciest clothes in order to get attention.  Male birds will grow brightly colored feathers in order to get the females attention and to see how healthy they are.  You can learn more about the common birds of the Rocky Mountains here.

molting, cicada, exoskeleton

A cicada has just molted or crawled out of its old exoskeleton.

Insects – In sharp contrast to humans, insects have their skeletons on the outside of their body.  This is called an exoskeleton.  The skeleton on the outside of their body does not grow as the insect grows older and bigger.  Due to this, insects molt or crawl out of their old exoskeleton in order to grow a new, larger exoskeleton.  Molting for insects is just part of the process of growing.  You can learn more about the common insects of the Rocky Mountains here.

molting, molt, snake, snake skin,

An old snake skin that has been molted.

Reptiles – Reptiles shed their skin because their skin does not grow larger.  This means that as the snake, lizard, or turtle grows larger the skin simply gets tighter.  At some point the reptile needs to molt or shed its old skin in order to grow new skin that is bigger.  Snakes shed their entire skin all at one time.  On the other had lizards and turtles shed their skin in smaller pieces.

Mammals – Many different mammals molt.  Some mammals shed fur throughout the year, but others will shed or molt their fur at certain times of the year.  For example, one of the main times of year that they do this is in the spring.  Mammals that live in very cold climates grow a thick winter coat to survive winter.  Then when the weather warms up in the spring they need to get rid of their thick winter fur.  You can learn more about the common mammals of the Rocky Mountains here.