The Bugle as you refer to it is the Rut ie breeding season. Generally all areas I know of are the same. Cows start coming into heat in early September. Things really start peaking in mid to late September. Generally the Bulls quite down and the rut stops by the second week of October. In Colorado your not going to hunt elk during the rut with a rifle unless you are fortunate to draw a special tag after 15 years or have the money to pay for a pay to hunt on a wildlife ranching outfitter.