So... about $2,000 is the cheapest I can set up (what I consider to be) a minimially suitable run to cage the birds if I can't get the critters under control. And that isn't roofed. Just a roughly 25' x 65' area enclosed by a 6' chain link fence and an electric fence charger. I'm somewhere around $10 per linear foot of fencing, no matter what rout I go. Seriously considering getting two 10' x 10' pre-made chain link kennels for dogs, opening them up to make a single "wall" (with a door) and connecthing the two with a pair of 50' chain link runs.
Still doing the math on that, and will need to set 4x4 posts both for strength - those wallsections are free standing, they have no strength of their own - and to provide attachment points when I move the bunny cages out into that area as well. and build a new feed locker.
On the trap front, got both traps set yesterday, used sprats as bait and to cover my human-like scent. One critter (unknown) thanks me for the gift and expressed its opinion of the trap by leaving its scat where the bait was onside the trap befor leaving...
It looks a bit like raccoon scat. Or deer scat that's been eating a bunch of blackberries and other things in seed right now. There's a vague "pelleting" but its so moist and seed filled there is no distinct shape. Or wet fox scat (minus the point ends). Apparently, wrong collor for possom.