Chris as usual brings up some good points! But just so no one is confused, Bulls come down to or over their way to the cows! In other words these bachelor groups are generally separated from the cow groups. It is very common to find these bulls much higher in elevation where applies, during the Summer months. These bulls will at their own pace will make their way down to these cow groups, the cows do not go & seek out the bulls until the bulls come into their areas I believe what Chris is saying is that the cows will choose the bull they allow to breed them. In many cases more than one bull will breed a cow in the 12-16 hours she is in heat or estrus.
Of course once these herd bulls establish themselves with a group no matter the size of these groups they can move anywhere even back to where the bulls came from if hunting pressure of sorts forces them to do so! The cows inherently will start seeking out their breeding grounds, this is generally in the areas they were born in. This is especially notable in non-hunting areas where elk are free to roam naturally without intrusion. Too, in these areas you will see these cow groups stay right in those vicinities they've been in all Summer as Bulls start to show on the scene that were not there previous to pre-rut!
Again, very good info related by all.