I'm going to stick to one encounter with - a snake!
It's a rattlesnake, which I saw crossing the road in front of me one day last spring, and so I jumped out of my truck and immediately started taking photos as fast as I could. You can use the tire tracks in the photo for a crude scale, because I didn't have time - or the desire - to try to put my rock hammer next to the snake. I had to hurry with the photos: not only was the snake intent on crossing the road, as soon as I appeared on the scene, it became intent on getting away from me!
It's kind of small for a rattler, I think. It is most likely the western diamondback, though I don't know the many different species of rattlers very well
Here, you can count the rattles on the end of the tail (which is, of course, where the rattles belong). I count 7, including the little tip. Folk lore would have it that the number of rattles are supposed to roughly equal the numbers of years a rattlesnake has been around, but a snake can shed it's skin more than once per year, which is when they grow a new rattle. So counting doesn't say much about the age of the snake.
This guy didn't rattle very much, which is one problem, in my opinion, with killing rattlesnakes that aren't near homes, camps, or ranches - I think there may be a chance that only the non-rattling rattlers survive - because it is the ones that give warning that are most likely to be killed by passing snake-killers - which will mean less warning the next time you get near one in the field. Consequently, I don't kill rattlesnakes unless they are in a place where they are likely to do some damage. I might have a different response to other species of poisonous snakes, but mostly haven't had to deal with any other kinds.