at every festivale!
if you scroll down enough on this wiki you can read about it here:boop
basically you catch them in your net (they're floating around town) and you keep them in your pockets.
I think you get the feathers as rewards from donating 100 million bells.
Green Feather - 100,000,000 Bells
Blue Feather - 200,000,000 Bells
Yellow Feather - 300,000,000 Bells
Red Feather - 400,000,000 Bells
Purple Feather - 500,000,000 Bells
White Feather - 600,000,000 Bells
Rainbow Feather - 700,000,000 Bells
I'm not 100% sure on this, but I think I'm right.
I don't get it. I think you can't donate bells to get the feathers in CF, only in WW.
Yeah, I think you'll need a copy of WW.