Sunday, July 4, 2010

What's Happening: Molting

A penguin's feathers are very important for keeping them warm and dry while they are in the cold ocean water. Over time their feathers may wear and break (imagine wearing a sweater everyday for a year, it is bound to get some holes in it, and look a little worse for wear). In order to replace these feathers, penguins go through what is called a molt, where their old feathers are pushed out and replaced by new ones.

A penguin's molt is sometimes called a catastrophic molt, because unlike most birds that will molt a few feathers at a time, penguins molt all of their feathers all at once. And if you look at some of these pictures you can see that catastrophic is a good description, they often look like exploding pillows.

An exploding pillow!

Molting is a 3 stage process and starts weeks before the penguin actually replaces any feathers. Their bodies are making the new feathers while they are gorging themselves on fish which they must do to increase body weight to endure the 2nd stage. Penguins are not waterproof when they molt, so in stage 2 they stay on land for 2-3 weeks fasting until the new feathers have emerged from below the skin. During that time they will not eat, so a few weeks prior to the molt they will increase their food intake to build up a fat reserve to live off of while they are on land. Since we record how many fish each penguin eats everyday we can usually recognize when a penguin is getting ready to molt since their daily food totals can double or even triple. In the wild stage 3 involves returning to the sea to replenish lost body weight.

Here are a few pictures of some of our penguins right before they start molting, notice how much bigger they look than a normal penguin.

normal African penguin

A penguin getting ready to molt

A normal-sized rockhopper penguin

A rockhopper pre-molt

In this photo you can see the wings of two penguins; the one on the right is just about to start molting.

Can you spot the fresh new feathers coming in?

Stay tuned for more pictures and video as our penguins complete their molts.

- Andrea


  1. Thanks for the great comparison photos!

  2. amw0409@scsncmail.orgOctober 7, 2010 at 12:14 PM

    wow. they do look like exploding pillows!

  3. Cool!!! Thanks for the information. It really helped my project.

  4. We have had the pleasure of observing many penguins around the world. Thanks to this site I now can see clearly the process and am able to look more closely at my photos to see which ones were in 'molt' mode. Very fun and educational!

    1. Seeing penguins around the world? Lucky you! So glad you could find this information helpful, thanks for following along.

  5. Im 12 years old, doing a project for class, about rockhopper penguins and this was really helpful. Thank You so much

    1. Great! So glad you were able to learn from this blog post.