What signs would one look for? I have read some great posts about how we know when they are okay even when the temperature is below freezing. But I doubt that one size fits all. Sometimes there are unusual, extreme conditions. What might some of those be? What about behavior that indicates a duck is too cold? Not just a duckling, but an adult duck. They tend to hide it, I am told, if they don't feel well, because that is their survival instinct. How would one figure it out? How about the smaller breeds? Their surface to volume ratio is much larger, so they physically cannot store as much heat as a larger duck. How does one scale up or down for that?