So I have 4 12-day old ducklings, and just recently they have started peeping for no reason. They let me know when they need food or something, but they now peep even when everything's okay. They have water, food, heat, and they're with each other. When I go back to check on them, they stop peeping, and then fove minutes after I walk away, they start again! Any idea why this is and how to fix it?