I don't think a cat got in. I think a cat figured out a spot where it could get a paw through and "fish" for birds.Seems to me that open feed would be a rat's first choice. How do you think the cat got in?
@JaeG That’s what happened to our quail a while back. I woke up and found that something had dug under and grabbed the legs off all the quail in a tractor on the ground (it had a wire floor). They were still alive just amputated. I was horrified. I had to cull all of them. Poor things. Most likely a rat. The hole near the tractor was too small for a cat.
No. there is no evidence of rats. And I'd know, because I had rats all the time when I kept poultry in Seattle. Also, the ranch where I keep my horses is crawling with rats. >.<Don't rule out rats just because you haven't caught any. Are there any signs of rats, like burrowing or droppings?