This is one kind of surprise that you never forget if it's really close when the buzzer goes off. Having a resident black snake or gopher snakes will keep these critters away from your yard.
That's a nice tight shot of the snake. I think that even if the rattler was in focus, it would not be sharp due to motion blur.
OK, so the first thing I checked was what lens you used to shoot this guy. Great detail and a very good shot of a rattlesnake - looks to be fairly mature as he's got a pretty thick body. Next thing - what did you do after you shot him?? And congrats on the new top row entry!!
Brilliant shot & congrats on your new 4th best shot; it's a good (if a bit scary) one to have on your profile page. As for those who want the rattle in focus, not me, I want to keep my eye on that mouth! That's the business end, anyway, other end is all bluster!
Nice capture of this snake. The square crop works well with your composition. I love how you got the tongue out and everything. I just wish the DOF was a bit deeper to get the rattles in focus also.