Here is SE Alabama our winters are never what one could call harsh. We sdeldom get into the teens, and snow is rare. So winter kill is not an issue ... I don't think. I am not certain, but I think what hurts the deer here is a combination of an extended summer/fall drought, coupled with a weak acorn crop. This was the case in 2010. I hunt 3150 acres along with several friends. We have tried to "manage" the population in this area by taking 75+/- does each year. We have done this for well over a decade. We have several 2010-2011 trail camera shots of deer that are "boney".
During years when the summer/fall rain is at or above normal, the browse is lush and the deer we have killed have been rolling with fat.
Right now, most of our small creeks are nothing more than a damp ditch. Only one of what I'd call a "major" creeks that is running through the property is flowing. Two of the others are holding water, but barely flowing. I hope 2011 is a "catch up" year as far as rainfall.