I don' t hunt in Co. but here are a few things that work for me. When we rifle hunt in Or. we' ll find a bull the week before and preferably the night before and every time we have gone in opening morning and taken them. Most of the big bulls that we hunt live in one small, nasty area. They bring their cows in for the rut. This is not to say they don' t move with pressure, rutting, or a migration. Elk can cover miles when they want but around here they seem to brush up and let hunters walk right by them. I imagine the country around here is a bit more brushy than Co. so this may be useless for you, but I hope it helps.