Well Im no expert by no means but I have for the last 3 nights or so feeding and watering my ducks around 10 pm then removing food and water. Drying up their mess so they have a dry bed to sleep in then coming back to feed and water them around 5:30 am. They seem to be doing fine so far. As I see, if ducks are anything like chickens, they don't see well at night so would most likely not eat or drink much in the dark anyway.