I also just whistle. I also shake the feed can while I whistle. You will find that with a correct feeding regiment that the whistle is quite effective. If you overfeed you can whistle all day and they will sit and look at you like you are a fool. Yesterday for instance, I flew my birds in the AM. I had 22 birds trap in about 20 seconds. They were in the trap before I had a chance to whistle. I overfed them a bit in the AM and had to leave before they were finished, leaving food in the hopper. When I flew them in the PM it took them about 5 minutes to trap, and my pucker was whistled out. I start shaking and whistling while the birds are in the nest. They soon get the picture. By the time I move them to the fly loft they know what it is all about. I think a good feeding regiment of twice a day, all they can clean up in about 5 minutes, late trappers get little if any, works well. There is many of times when they land and go straight in the trap, before I get the food out, with no chance to whistle. The whistle does work though. I have called them in off the neighbors roof with the can shake and whistle. It is great for training the first few times they are out. You can also call them in out of the air, if you spot a hawk or a strom is comming.