Whistle, can of seed, I use a cowbell, hog call. It doesn't matter what you use as long as you are consistant. Use it everytime you feed. After the birds loft fly a couple of times catch them and release them in sight of the loft. Do it while they are hungry and call them as soon as you release them. They will learn if they want to eat.Do you mean train with a whistle? if so dose it matter what kind?