Bob, I have seen that myself. I actually have pictures of a garter snake trying to eat a garden toad, but no screaming. I have pictures of that one, which made my wife mad because I disturbed the snake which "let go" read puked up, the toad. Later I heard that same scream you talk about from the pond, where a snake had latched on to the leg of a great big bullfrog. That critter was also "liberated", this time without the wife's knowledge.
