Really good post here. I was going to wax on here, but Rack-attack has stolen my thunder. Photoperiodism, photoperiodism, ... type that 10 times fast!

Just a note, in whitetail populations around the equator (i.e. way south of the USA), the deer breed at all times of year, and individual bucks drop antlers and grow new ones all through the year. It varies by the individual deer.

Judging from that fact, I wonder if deer in the southern US may be a little more variable in exactly when they rut. Here in the northern latitudes, fawn drop is real consistent year in and year out, indicating the rut is kicking off about the same year in and year out (again, like Rack said). In warmer climates, it probably isn't as critical to fawn survival to be born at one particular time.