Yes. You have definitely given me direction

They will be staying separated into groups that's for sure. When I get to the point of needing it I plan to build a small run that the chicks can access from the brooder.
On the run extension I thought of breaking it up into thirds. Each section would be about 10'6" wide. So one section would be 1005 sqft the other two 765 sqft.
However I do it it will be built a little different than the other run. I'll use hardware cloth on the sides and for the top I'm planning to use 2"x2" 16 gauge fencing 100'x72" roll
http://www.redbrand.com/Products/SpecialtyApplication/YardGardenKennel.aspx Support the wire with the 10' lengths of top rail that is used for chain link fencing.
It should be a little cheaper and much easier this way and I don't think I have any worries with something getting in. What are your thoughts on using this wire fencing? I think the chances are slim that something as small as a mink would be around and I'm really not worried about snakes if the birds are of a decent size. There will be doors between the existing run and extension anyway if I want to close them at night.