Last week my beloved Tom turkey was killed (head and neck chewed down to the bones) in what I thought was a pretty safe pen. It's hardware cloth all the way to the top (6 feet) on 3 sides, with chain link covered in chicken wire in back. There is welded wire attached at the bottom all the way around about 18 inches (can't trench down due to extreme rock). The top is covered in different areas with either welded wire, chicken wire, nylon deer netting or plywood. I'm assuming the culprit was a mink or weasel, as possums or coons couldn't fit (and Tom wouldn't sleep near a wall anyway). I know there were odds and ends of gaps, rat holes where a skinny thing could fit-not many though so it most have been a professional predator, scoping the place for a while. Will those skinny guys climb the side and drop through the top? I put tarps on the sides and part of the top now, figuring it's too slippery for them to climb. Temporary fix, as heavy rains are vexing me with the weight, it's ugly as sin, dark inside, and hard to keep in place with wind. I was going to put 20" metal flashing all around the bottom of the chain link section. Will any of these predators be able to get over that? I also have some massive white pines just behind the pen with branches overhanging. Is that an access point too? I am unemployed now and on an extreme budget, so fixes unfortunately have to be very cheap.
My experience tells me a Weasel can pass through a very small hole, as they are very flexable. A hole only 2 inches across is completely negotiable to them. Second choice would be a Possum or Coon, and they do climb under roofs. Rattus Rattus will seldom attack anything larger than itself, but have.
I'm so sorry for your loss! Sounds a lot like a raccoon. I didn't know we had weasels or minks in MD, but I live in a more urbanized area than you do. Is there any way you can use scrap wood to make a roof support to help with the tarp or netting when it rains/snows? I noticed this weekend when I was out your way, that off of 64 someone had a sign up saying "free palletts". Perhaps you could use some of them for the wood, and it would be free. Just an idea.
So sorry you lost your turkey! Yeah, most predators, including weasles will climb up hardware cloth and enter through the top. I would make up a frame from some wood, and use hardware cloth to make a nice top for you, and also cover the back wall with the hardware cloth. It's really the only way to keep those nasty predators out.