Is it enough space

[arhawkeye]

I'm sorry I meant that the yard has a 4' fence the run itself I was gonna fence in up to 6' or 8' high. The top might have to wait a little while though. As far as under. I am digging 1-2' down to burry the bottom of the wire and a trench of rock to detur any digging

 

[BayBay Peepers]

I meant if you were to let them free range. I don't think they would try to escape you with a four foot fence
In the meantime before you add a top to your run you could strategically place some items that would offer your flock some cover. Mine free range all day and when they see a hawk or turkey vulture they always run for cover.

 

[aart]

I'm sorry I meant that the yard has a 4' fence the run itself I was gonna fence in up to 6' or 8' high. The top might have to wait a little while though. As far as under. I am digging 1-2' down to burry the bottom of the wire and a trench of rock to detur any digging

Instead of digging that deep, just dig 1-2" then go out 18"...... an apron is more effective against diggers.

Corner pieces in pic are out of scale, but don't forget the corners.