It would be difficult at best. I can stand on either my back or front porch and count 5-6 hawk nests in either direction. We also have frequent coyotes and owls. Stray cats and neighbors dogs as well. Also, our neighbors would not be impressed with having chickens in their yards. We live in what used to be a rural community but is becoming congested. Also, if they ran off into the woods, I don't know how I would find them. None of them are old enough to lay as of yet (we have 3 that are close - the rest are 9-10 weeks old).
We have 5 acres. Only 1/3 of an acre is cleared. The rest is wild woodland. It has very thick underbrush that would require a hatchet to get through. But the land is deep - not wide, so the neighbors are close. If I let the chickens out, I have no way of keeping them out of the woods or the neighbors yards.