Oldandnew
20 years ago, for about 10 years in a row, I hunted the eastern Montana area, from Glendive, Miles City, on north to the Glasgow and all around Ft Peck Reservior. Mostly in Mid September, Never saw a rattler. Don;t doubt that they are around, but at that time of the year will be concentrated in rocky denning areas, if you see one you will see alot more off all sizes in the same area, but generally not in the areas and cover you will hunt for birds. Lots of sharptails bye the way in those days, huns sporadic, as well as sage hens. Lots more sage hens in Wyoming in those days, in the great basin area, lots more rattlers too! Saw a lot of rattlers those days in the Nebraska sandhills also. What you may find in Eastern Montana, is porcupines, IMO worse than the rattlers, some dogs just can't stand to leave a porcupine alone. I also had a Grizzly Bear moment on the north end of Ft. Peck, in the early 80's, quite a surprise, dogs jump a mother and two half grown cubs from a willow thicket creek bottom, dogs, hackles up, tails between their legs, running and growling pell mell for the truck. All in all a lot of great experiences and a trip well worth making more than once. By the way depending on winter mortality, sometimes lots of pheasants in that area if you go later.