Some of the behaviors I have seen in my flock that defy "the books" and common knowledge are:
--They do not always molt a certain time of year - sometimes a duck will molt in winter, or not for over a year.
--They do not all have the same comfort levels. Some prefer it a little warmer, some prefer it a little cooler.
--My ducks do not sleep through the night - they awake often, and chatter.
--My ducks will not huddle together if they are too cold.
--Not all flocks have a duck-in-charge that they all follow all the time - mine don't.
--Some ducks play "hop on top" just for fun, not to prove dominance.
If I think of any others, I'll add to the list.