Okay guys I think I can help answer some questions on these.
I work for a website that sells these extensions to DIYers and salons, so I am wrist deep in them for a good portion of the day.
The roosters are actually genetically modified breeds varied from dominiques tO australorps. They're bred to not have any fluff at the base of their saddle feathers. Basically their butts look like beautiful heads of hair. These birds are allowed to live past maturity so their feathers can grow as thick as possible. There are only a hand full of farms in the country that actually raise these kinds of birds, and right now most of these farms are completely bone dry on mature adults right now, since this trend has absolutely boomed in the last three months. Eta: these birds are allowed to live wayyyy longer than a meat bird.
So we get the feathers in. The ones we like to keep as natural colors actually still come attached to the saddle, like how a fly fisherman would buy them. We can get as many as 250 really good feathers off a saddle, or as little as 20. You cannot use really thick feathers, like the tail feathers because they will get ratty much faster than the skinny saddle feathers.
Most of our feathers come in bundles though. They are solid colored or striped. These are dyed various colors then set to dry. Once dry they are ready to be sorted and shipped.
They are sent with a bead, pliers, and a threading kit. Feathers cost around three dollars EACH. ( believe me, the farms are not sellin them for much less than that right now! They are getting their fair share out of this trend too! Woo hoo!) and as far as I know we are the most inexpensive website right now. Anyways, so your hair is threaded through the bead with the feathers(s). You use the pliers to pinch the bead off tightly. These have held feathers in hair for longer than six months. These feathers are washable,
Blow dryable, even curlable.
Websites can't even keep these things in stock right now and the farmers don't know whether or not to produce more birds since trends come and go...