Rattlesnakes blend in with their surroundings very well- certain kinds (like speckled rattlesnakes) love to hide in rock crevices, whereas Mojave rattlesnakes have dull green coloration that blends with desert plants, & they can be found lying in any little shadow they can find (for relief from the heat of the sun), or if they smell water, they'll sit under a dripping hose faucet...they're not so particular. And rattlesnakes don't always rattle, so watch where you put your feet & hands. It's not safe to just step over a fallen log (or cactus), because a rattlesnake may be in the shade of that log on the other side. Instead, step up on top, then take a leap beyond (after looking where you're going, of course). If you're rock climbing & sticking your fingers in rock crevices, you're just wrong... If you do see one, keep in mind that you can out-WALK them, so no need to run. They're ambush predators, & mostly they just hold their ground- they don't have speed (other than their strike) so staying out of reach is what matters.