Feathers are unique in the animal kingdom. All birds have them, but no other animals do. Even other animals that can fly, such as bats, don't have feathers.
So why feathers and not fur or scales? Feathers are vital to birds for many reasons. Most importantly, birds use their feathers to help them fly.
Feathers are made of a lightweight material called keratin. It’s the same thing our hair and fingernails are made of. Keratin allows feathers to be lightweight, but also flexible and rigid enough to withstand flight.
Muscles are attached to the base of each feather so the bird can move them as needed. When flying, the feathers move together as the bird flaps its wings down. When the bird moves its wings up, the feathers move apart to allow air to pass through.
Besides helping birds fly, some feathers help keep birds warm. Birds can trap air close to their bodies using these feathers, which keeps them warm. They can even rearrange their feathers to trap more or less air, depending on the temperature. Sometimes when it's cold, you can see a bird fluffing its feathers. It does this to get warmer.
Feathers are water resistant, which helps keep birds dry in the rain or in water. Feathers, especially dark-colored ones, even help protect against the sun.
Feathers are an important part of a bird's identity. It is part of what makes it easy to tell a cardinal from a blue jay. The colors of a bird's feathers also help attract a mate.
Some birds use their feathers to stand out, but others use them to blend in. The eastern screech owl has feathers that are close in color to the trees where they nest and roost. This makes them hard to see.
Just like we shed our hair and grow new hair in its place, birds shed their feathers. This is called molting, and it is when damaged feathers fall out and are replaced by new feathers. Most birds molt once or twice a year, but larger birds replace their feathers less frequently.