Logic would suggest that the oldest bucks should show up as the rut approaches, as it would make sense that older bucks are going to be the most likely to "cruise" great distances looking for receptive does.  But surprisingly, over the years, I've found that there is no age difference between the three different groups of bucks we annually track on my place: the summer residents, the fall-season range-shifters, and the rut range-shifters.  Each of the three groups have almost exactly the same age-structure.  That finding really surprised me.

And that's why last year was such a shock.  Now summer residents generally only make up 1/3 of the bucks we're going to have to hunting during the hunting season, but that group usually includes all ages of bucks.