I've never run across a copperhead in a tree. I know they can climb, though, because I've seen them and pygmy rattlers up on palmetto leaf. A pygmy got me from a palmetto leaf.... didnt see the little dude. Copperheads are easy to spot, especially on those green leafs.
Can you imagine a venomous bite to the face?? Holy smokes, that's gotta hurt.
Used to come across them on occasion up in the barn rafters hunting rats. Always marveled at their climbing ability for such a relatively short bodied snake. Got eye to eye with one retrieving eggs from under the barn one morning - had a stubborn banty hen that refused to lay anywhere else. We gave each other a "pass", but he/she was less than 6" off the end of my nose for an eternity (at least 6 seconds). Amazing how quick your fingers and toes can hit reverse while you're on your belly.
Ouch! That would sho-nuff be an unpleasant experience! And I've never seen them in trees either, but it makes sense to me once he mentioned about the flooding.
I found a juvenile timber rattler inside the plastic all weather cover for an electric outlet on my front porch. It pays to be aware and to remain watchful even where you least expect danger.