They eat Nutrena brand all Flock Pellets and what ever they dig up out of the sand. We are located in Central Florida and the temps now are in the 80's. They always have fresh water available and a small pool, which I don't understand why they choose it most of the time. they are in the pen in the daytime and in the house at night.
Thank you for any help.
If it were me, first I would not worry too much at this point. As I wrote, it is not uncommon. But there may be something missing in their diet. In my experience, some ducks simply have more need for some things than others. So this food - which many many people use - may just be lower in something that your ducks need.
So, I'd get some poultry vitamins - I think they are $4 for a four ounce packet - that can last for months. Give that once a week in their drinking water.
I might add a couple of tablespoons per day of good quality cat kibble to their food, for a few weeks. That can provide some extra protein and vitamins and good fats, perhaps, to their bodies. I tend to think of cat kibble as helpful for feathers and bills.
Otherwise, they seem healthy, yes? The bills are not soft, or have odd bumps or depressions?