The first winter we had chickens, we moved the coop up by the house. It had been down by the garden. Over the winter, I had visions of making a chicken moat to go around the garden, for the chickens to "help me" keep the grass and bugs at bay.
Then I realized how MUCH easier it was to take care of the chickens with their coop up by the house. No walking down that steep hill to the garden and worrying about slipping and falling.
So by the house the coop has stayed. And grown two additions, so now it's too big to be moved.
But I bet they would have really been great at keeping the grass from growing in that area, and they would have really taken care of the grubs!