That's a Brown Vine Snake, OXYBELIS AENEUS, famous for it incredible slenderness. The one in my hand is about is about three feet long (1 m) and when it's stretched out it's hard to believe that such a thin body would have enough muscles for it to move about.

He did have enough musculature, though, to offer some quick strikes at my hand, which made a great show but never made contact. Once he was caught he became very tame, not squirming at all.

Brown Vine Snakes specialize in moving through branches of shrubs and trees, feeding mostly on lizards, especially anoles. Campbell says that during the day the species usually stretches out on vegetation two to six feet off the ground (0.5-2 m), and at night hangs loosely coiled, head-down, a little higher off the ground. Brown Vine Snakes tend to wait for victims to come near them, depending on their camouflage. Who knows what he was doing on the lawn outside the kitchen?

The species is distributed from Mexico through Central America to southern Brazil, so it's an iconic species of the American Tropics.

I released the snake inside a dense thicket beside the hut, draping his body horizontally atop some branches before letting go. The moment he was free, it was amazing how fast he shot through the three-dimensional world of green stems and leaves, dodging up and down, right and left, like a fish in water. How beautifully this species is adapted for an arboreal life!