I started with a very very basic chicken tractor when they were old enough to be outside...but had no parents to keep them safe. This served its purpose and I still use it as a breeding pen(so nice to have around like others have mentioned). HOWEVER...I live on 5 acres(mostly wooded except for maybe an acre of backyard and sideyard). I bought a chicken barn on craigslist and I LOVE it!!! You should lock them up for a few days(once they are old enough to be outside and have a little common sense...say 10 weeks?give or take a little) I kept mine locked up for a whole week(it killed me but it worked). After that week they new very well where their home was and they have continued for almost a year now to play and run outside and when it gets near dark they start marching themselves right back to the barn. We wait until we're ready to go to bed ourselves and then I will run out and lock up the barn. In the morning we let them out and they really do stick enjoy free ranging and it cuts WAAAY down on the amount of store bought food that they eat. When we went away this winter for a week on vaca. my neighbor kept an eye out for them but I just left their chickie door open for the whole week that way no one had to be bothered with letting them out and locking them up. I KNOW it's a risk and we have lost 2 chickens this year to hawks but that was early on and they were younger. Now our big roo really seems to be on top of things trying his best to keep the flock safe. They spend most of their time in the woods scavaging through the leaves for bugs and this keeps them camoflaged from predators. They also love to hang out under the big pine tree in the side yard and whenever a hawk flies over(we have our share! trust me!) they all run for cover under the tree. I've just come to terms with the fact that we may loose a few each year and that's ok with me. I get enjoyment out of watching them free range around our property and I know they prefer to be free so it works out. I like to keep it simple and as close to old fashioned as possible. I will allow them to hatch out some babies every year and this should help replace the ones that we may loose here and there for whatever reasons. PS. I know people that keep their chickens penned up who have lost just as many as me(or their whole flock) b/c once a predator gets into your pen the chickens are stuck. But like I said, I do use my tractors for breeding pens and raising babies. Here's the pics: Blessings,Keri
Also check the laws in your area as where I live (in the city) you can have 10 hens BUT they must be in a fenced in PEN not yard at all times, NO free ranging is allowed here.