I have my chickens in a yard, about 600 foot of fence, I only have less than a dozen anymore. But you need to be sure they have water, like you said a pond would be water, if its clean water. And they need some kind of grit. Like course sand to very fine gravel. That is how they digest their food, they grind it up inside. I also always give mine oyster shell, it helps as a grit and to make the egg shells. And they need some grain, if you have very small hens you might want cracked corn, it is alright for big hens to. I also give mine laying pellets, it helps to keep them laying and gives them a good diet, for their health. When I was young and we didn't have a dog problem like I have at times now. We just gave them shelled corn, as we had 150 acres for them to roam on and figured they got everything they needed. But in smaller places they need some help. Fact is mine have free choise of cracked corn and pellets at all times, But they still eat the bugs and grass, maybe not at much grass, but quite a bit.