Southwestern Speckled Rattlesnakes

I heard the tail flopping that a female rattlesnake does during courtship from a short distance away, and was able to see her and the male from behind a tree. He followed her (and I followed them) for the next hour or so, before they eventually curled up near a boulder and began mating. They were still there in this position 2 hours later, and will likely be all evening.