Shims at Lowes are untreated. I bought a couple packs and the birds are having at it. I lay them in different places and the Tiels find them and don't let go of their shim until it is gone. I found this is the easiest way to give them something to chew on while searching for other stuff.
Lightening hit a maple tree and broke some branches. I plan to if I get to it to put a big branch in a Christmas tree stand for them. With the bark still on I think Phoenix will be able to climb up to a branch.
There are no lights outside the cockatiel room. I do not cover the Tiels and let them have a natural dawn and dusk. My bird lights are still set to 9am to 5pm.