The 3rd day we were there, he stopped being able to keep any food down. Hubs' aunt freaked out, thought he was going to need surgery, and started looking for a no-kill shelter she could take him to. He was still happy and playful, so I wouldn't let it happen. I did some googling (and made calls to the vet) and determined that since he wasn't lethargic, we needed to give him a day without food to clear out his system. Hubs' aunt was still certain that she could not keep him anymore, so I decided that he would be coming home with us.
The next day, he kept his food down just fine. It turns out that he had been left outside, ALONE, for too long and stuffed himself on hackberries and dead leaves. Hubs' aunt was still certain she no longer wanted to keep him, so it was official. He became one of our clan. We bought him an id tag with a jack o' lantern on it. It's been decided that he's our anniversary present to ourselves.
I was worried about bringing him home to the birds, but so far, all is well. He doesn't wake up when the birds are singing/screaming, and he doesn't bark in response. THANK GOODNESS! We're working on basic potty training and no biting. He's great on the leash, and I can tell he's going to be a great workout partner! Because he's such an odd mix, we have no idea how big he is going to get - this will prove interesting :)