I'm not sure about the length of day idea. I use to hunt about 40 miles from where I do now and the bucks began the rut about a month earlier than where I hunt now. The moon is the same in both areas also. The weather, cold days, is the same also. The biggest difference is the origin of the breeding stock. In the 50's, when the deer in our area was stocked the area where I first started hunting used a lot of northern brood stock while the area I hunt now used a mixture of western Alabama deer as well as some other brood stock. Now we have an over population of deer almost everywhere in Alabama and it is constantly changing the breeding days. Young, healthy6 to 8 month old does will breed, their offspring will do likewise and the entire rut is getting skewed. I've probably seen 20+ recently born spotted fawns in the last 3 weeks. The bucks hardest rut time in our area is about the 3rd week in Jan, but you will see worked scrapes on into April. Who knows what the rut will be in 20 years.