supposedly to be every 20 minutes for an adult duck. I have spent hours watching ducks, waiting to see when they poop when I had to check who was pooping a certain kind of poop that didn’t look healthy and yeah, it is about every 20 minutes for an adult, but babies poop a lot more…I have read that ducks poop 96 times a day. I have not been able to count the poop ever to see if that is correct but I sure do believe it. lol