I’ve seen them do that through the day and especially when coming out of the coop. They come running out quacking and then all drop to there bellies. It’s kinda comical to watch. They eventually get up and waddle to where ever they are going and lay down again.Video would be helpful.When its very cold my ducks will stand up,move and then hurry and sit down because there legs get cold. They aren't going to be doing too much when its that cold.
That was all happening at -15/-20C.