My nephew, an avid hiker and climber, lives in CO and resided in Golden for several years. He says the trails and hills around there, where that fatality occurred, get a lot of foot traffic. He's seen a rattlesnake there once, so I guess they do avoid people if possible.

Googling rattlesnake bites, as RM suggested, results in some pretty horrible images. You might not have died but might wish you had. While there only 10-12 or so deaths a year from snakebite in this country, there are a total of 8000 venomous bites.

So, I'm glad I live up near Canada in the east. Lots of snow, nothing but garter snakes I've seen or heard of. I will happily take the snow. Snakes give me the creeps.