So much wrong here. Belly color has absolutely nothing to do with being poisonous. Second, that is not a water moccasin. I grew up with them on the Tennessee River, occasionally beating them over the head with my paddle to keep them out of the boat. It's just an extraordinarily fat water snake which has probably eaten lately. Next, as I posted way, way above, the head is all wrong for a pit viper, the family the moccasin belongs to. Finally, poisonous snakes, including rattlers, do climb. They don't normally climb because using their venom on ground prey is more efficient than the non-poisonous breeds that climb for birds and small mammals. However, the last rattler we had our neighborhood herpetologist come and pick up was up about six feet up in one of our gardens in a low tree. My wife came face to face with it. (She's not especially afraid of snakes - she grew up spending a lot of time in the woods, as did I.) It couldn't have climbed much further, because it was a low-growing shrubby tree, but there it was. As I said, we have always had a rodent problem, having 3 acres of woods and having thousands of acres of woodlands around us, with some easy funnels into our yard for deer and you name it. Snakes are very helpful and we only have the pit vipers relocated. They help save the garden from voles, the foundation and patio from chipmunks and the attic from squirrels. They will even kill the odd groundhog, although they can't swallow them. You guys can continue to be horrified, but they're my friends...