You read their body language. For instance, if the snake is relaxed and not moving quickly, it’s not hungry. If it is very attentive and tracking movement, it’s probably hungry. We tell them that it’s not feeding time with what is called tap or hook training. Using a hook, we gently touch the nose of the snake and after a short time, they learn that it means there is no food involved. When you interact with the snakes long enough, you learn to recognize their moods and what they are trying to tell you.