'Blacktail' by Rick Williams. Met this very healthy-looking 4' rattle-guy along the lower Bear Canyon trail. He was just trying to finish getting across and had almost made it when I came along; too bad he was in heavy shade. Lucky for me, and my camera, he was mostly behind a large bush which had a couple openings for the lens so didn't have too much personal exposure (no pun intended). Almost seemed embarrassed he'd been made, it never attempted a rattle or even to coil ... blacktails are generally mild tempered.