As for the resident bucks disappearing and new bucks showing up, this is something I was convinced occurred due to my many years of trail-camera data. Talking to other biologists, they had also seen similar trail-camera evidence. Finally, a couple of universities finally tracked this behavior with GPS collars (Miss St and Auburn). It turns out some bucks have a "rut range" - a range they only live in for the 5-6 weeks of peak breeding, and this rut range may be completely outside of their normal fall range, sometimes miles away. MOST bucks that have a separate rut range, go back to that same range year after year during the rut. However, a few actually choose a new rut range every year, never using the same area twice.