My ducks have a certain routine - come back by then pen (which is locked to stop any rats getting in), eat as much as possible, have a bath then wait for me to open pan and put to their boxes.
If I am late it's a nightmare, they don't want to come off the pond - which isn't bit enough to keep them all safe - then they make a mad dash of the pen and boxes and end it going to be with their sworn enemy!!
We have the whole area illuminated by outside christmas lights so if I spent too long with the goats I can still see the ducks - but if I leave them on once they are in I can hear them talking away together - so I think light = up and dark = sleep, as for the barn owl bit not so sure - we have a pet owl who'e avairy is 20m from the duck pen and will quite happily sleep in the grass surrounded by the ducks - no problems yet - poopee is a bit well fed though