I like the cast iron dinner bell.
Sometimes in the winter when I feed, after I start throwing out the flakes, I will yell (ok--screech), "Pony, pony, ponies." They are usually already on their way.
Two summers ago, packed in to Eagle Cap Wilderness, all the horses were grazing in a meadow. It was marshy in some areas and we didn't want to slop through it. So I tried the screech thing. Guess what? Mine came and brought the others with them! It helped that we fed beet pulp when they were high-lined.
The trail is the thing....Louis L'Amour