Found near Taos at the rio grande bridge gorge, but not common this far north? This was taken at sunset so snake is more orange in photo. 3-4' long, very green, it crossed path between me and friend and got into strike pose before I backed off. Rattle was small, no black stripes, very blunt, and it rattled.
Crotalus is a genus of venomous pit vipers found only in the Americas from southern Canada to northern Argentina. The name is derived from the Greek word krotalon, which means "rattle" or "castanet", and refers to the rattle on the end of the tail which makes this group (genera Crotalus and Sistrurus) so distinctive. 32 species are currently recognized.