Lots of good info here. I deal with a lot of rattlesnakes as I work on three Arizona golf courses. Mature rattlesnakes, and I presume other venomous species, are capable of controlling their venom output. They will only put out venom in direct proportion to the threat they perceive. People often get a dry strike, a simple puncture wound with little if any venom injected. The snake sees you as something they cannot eat and thus save their venom for the next meal. The problem is if you really startle/scare them you may very well get a full shot. Baby rattlesnakes have not achieved this level of control and you will usually get a full shot of whatever they are packing.

In our neighborhood you just don't go out at night without a flashlight and shoes. I will only kill a a rattlesnake as a last resort. If after being moved (like porcupines make love...carefully), away from golfers, family or pets they return repeatedly, then and only then will I dispatch them to rattlesnake heaven (boy, that's a scary sounding place). I'm not crazy about snakes but I HATE rats and other related vermin.