Pretty sure that's a mojave green... about the worst thing you can get bit by in the continental US bc the venom contains both neuro and homo toxins unlike most snakes which contain only one or the other.
Oh great. All we need is Mojave Greens along The Front Range. From what I've been told, the snakes along The Front Range are a green phase of The Prarie Rattler. Any Herpatologists out there? Do we have western diamondbacks in this area?
FYI this bugger was towards the top of the trail. The trail up follows along Calypso and Tagger before crossing the scree field. Once you cross the scree the trail starts switch backing up to Breezy, or the walk off. Our friend was on the left side of the trail, after the scree, and before the first switch back. I believe the trail even has a folk there, but I'm unsure of the climbs, or walk off that corresponds to the left fork. Hope this info helps everybody.
I'm the one who actually got close enough to snap the photo for Eckhard. I happen to be a professional herpetologist & don't advocate getting that close to them for anyone else. It is not a mojave green. It is a very colorful common Colorado prairie rattlesnakes (Crotalus viridis viridis for the geeks out there). It was far enough away from the trail that I don't think it is an issue. It was at the upper base of Whale's Tail well below the trail to the bulge wall area. Plus, it made A LOT of noise. Didn't get a look at the rattle, but it sounded big enough although the snake itself was only around 24". Tom: there are NO diamondbacks in Colorado. Only 1 species on the Front Range. There is another species in southeast Colorado & a 3rd species on the Western Slope.