Zuma, the Migratory Bird Laws were written by Teddy Roosevelt in the early 1900's. At that time the Snowy Egret, White Heron, Sandhill Crane, Whooping Crane and Great Blue Heron were being hunted into extinction by market hunters. Think about all those photos and movies depicting the Gay 90's. All the women were wearing hats with massive amounts of long feathers. The best feathers usually come into play during mating season, so the birds were being killed without being able to reproduce. We are still trying to build the Whooping Crane population back up.
The law is a bit unusual in that they don't have to prove that you personally killed and took the feathers. All the law requires is that you have illegal feathers. The only birds that we are legally allowed to possess are those that you can legally hunt. So Canadian Goose feathers, Duck feathers, Turkey feathers and other game bird feathers are legal. The law doesn't say anything about what you do with legal feathers, buy, sell, trade, whatever. You just can't do ANYTHING with protected species feathers.
I had occasion to look up the law because I picked up a bunch of Pelican and seabird feathers while strolling along a beach in Florida. After I looked up the law I put the feathers in the trash.
I knew a woman that picked up a Blue Jay feather and stuck it in her hat. A Conservation Officer saw it and wrote her a $175 fine.