Re: Are feathers solid or have small structures?

Feathers are solid structures with hollow spaces in them. If you see a 
feather closely, you'll notice that the stalk(also called the ratchet) is a 
hollow. This makes the feather very light weight and thus helps in flying. 
You might also have noticed that the hairs of the feather tend to stick 
together. This is because each hair consists of tiny barbs and barbules, 
which project out from either side of the hairs. These intertwine with the 
adjacent hair's barbs and barbules, thus creating a velcro-mat like 
situation. That's how the hairs don't get separated even during flight. They 
come apart only when we pull them apart and can be even arranged together 
again.