It might likely just be highly visible to them in deeper water as well , we must remember they see the world different than we do . Not sure why it works, but it seems to be something you NEED to take with you when you visit there .
And to make it more interesting feathers , not plastics , black plastics get about 1 bite to 6 or 7 , this is likely do to the water temps. making the plastics not look real .