I've used them for a year with my birds, and have used them for horses extensively as well. For the ducks, the first few days or even weeks after the pellets are new, you can scoop out the solids which will be on top. They might have a few pellets sticking to them. Underneath there will be a wet spot where extra moisture from the droppings accumulates. This spot I fluff up and mix into the rest of the bedding. The moisture causes the pellets to break up into nice soft sawdust, and by absorbing the moisture, also absorbs the smell. After a while, the entire coop will be broken down into sawdust, and then the moisture won't be absorbed as much, so then I remove the wet spots. And then sooner or later, you'll just have to empty the entire thing and start over. You'll know when it's time.
In the winter, when things freeze solid (I'm in northern New England), I still use the pellets, but as a base layer. Over the top, I put a layer of hay, where the droppings accumulate and then freeze. They glue the hay together, which I can then remove in one piece when necessary. The pellet layer prevents the hay from freezing to the floor.
Edited by nhrocks - 10/3/15 at 5:23pm