Wow, sounds like it's going to be great when finished. My flock
is jealous. As for the naturalization, it might take a while to
get some growth on some items, or depending on how much you want
to spend, since the more mature, usually the higher the price,
but....what about planting a few real trees and bushes that are
bird safe. Can't get much more natural than that. Don't forget
white pine is always good. If your local home improvement store
has what mine calls "culled lumber" bin, you can find some great
buys in there. Birds care less that a 2X4 is a little crooked.
Culled 2X4's, 8 ft. long is how I keep my Macaw in cheap chew
toys. I saw them into blocks, drill holes and string up. With
the kind of space you are going to have, you might even use some
to build you own play areas.