Molting mysteries, unlocked

Have you ever seen feathers all over a habitat at Zoo Atlanta and wondered if a bird exploded somewhere? I wouldn’t blame you for thinking that, but those feathers everywhere aren’t a bad thing! They are just a sign that one or more of our birds are molting, which is a normal, healthy process that all birds go through at least once a year.

Feathers are made of keratin, the same thing your hair and nails are made of! Because of this, when feathers are damaged, they are not able to heal and fix themselves up. The damaged feather will need to be dropped and replaced with a new, stronger feather. That is exactly what molting is; the complete or partial replacement of a bird’s feathers. A complete molt is when a bird drops and replaces all its feathers. A partial molt is when a bird drops only some feathers, usually the primary flight and tail feathers. If a single feather is completely lost, not just broken, it will immediately begin to grow back instead of waiting for the next molt cycle.

Birds molt for a variety of reasons. The main reason is to have a full body of fresh, strong feathers that have not been faded, worn down, and misshapen with use. This ensures that they can fly properly and efficiently. Birds can also molt from stress, diet changes, climate changes, disease, change in light exposure, and many more reasons. Some birds will even drop feathers when scared or being chased by a predator to escape at the last second!

Molting takes a lot of energy to complete, so birds tend to do it during times that require the least amount of energy elsewhere. This means they won’t be molting during the breeding or migrating seasons. Birds are also often partially to completely flightless during a molt, due to the lack of feathers. When a molt occurs, what feathers are molted, and how the bird looks after a molt varies by species, age, sex, and even by individual!

Birds may look the same, a little different, or like a whole different bird after a molting cycle. Some bird species are known for their brightly colored plumage and often those that have this, called alternate plumage, have it for just a short period of time during the breeding season. They will then molt the bright feathers away after the breeding season is over and have a slightly drabber appearance for the greater part of the year. This plumage that birds have for most of the year is called the basic plumage. They will then molt again before the next breeding season to have those bright colors again to attract mates.

Other than feathers on the ground, you can often tell if a bird is molting by just looking at them. They tend to look a little messy and scraggly, sometimes with a feather sticking out here and there. With the variety of birds from all over the world that Zoo Atlanta has, you will probably be able to spot a bird that is molting at any given time! Keep an eye out for those native birds as well and after a while you will be able to tell if a bird is molting and even what plumage the bird has!

Madelyn M.
Keeper I, Birds