My boss use to laugh at me because my dog loved super balls. I guess they left the oily scent where the bounced and he would shake his head at me saying you can learn something new everyday even from a beginner. Because of my lab's love for the stupid ball he would follow everywhere it rolled or bounced until he found his treasure. AFter that it became a game to throw that dang thing in the nearest cornfield or brush and without fail my pup would bring it back. When we ran our first stake i realized what he was doing. If he were not the first dog run, he ran with his head straight up, scenting where the bird was brought back by the previous dog taking a straight line to every fall. He could do just as well if he were the first dog in line but he didnt' mind a shortcut where he found it. Not that this is the way to train, but it does give a hint to the process. We scented our "birds" (training dummies_ with anise oil. It is a good scent, they like it, and remains for quite a while needing refreshing every week or so. You could take anything and scent it with that, a hankerchief tied in a knot for young pups if you don't want to use a bird's wing. Let them retrieve it a few to put together the need to find and the reward for doing so. THen Give them an easy blind, by giving it a toss where they are not looking and then turning them around and sending them for it when they can still see the white kerchief. THen after that, drag it, letting it touch here and there close together in the beginning, and then further and further apart. DO this when the dog is not present, then bring your dog in. He will recognize the scent, and seek out the path. That is what i would do.