StrutNtom is right they are the goats of the woods, constant browsers. Although they never become dependent on a certain foodtype they will eat what you put out for them unless you run them off regularly, then they will still come in at night to eat it. They are opportunists. Just like most of the year they will not tolerate our scent and avoid our paths through the woods, yet in the winter when the snow is deep especially if it has a crust of ice on it they will tolerate our scent and walk right in our tracks.

The corn will not kill the deer, No one said the corn would kill the deer!
It is the sudden change in their diet that kills them. From what I have read (and apparently tsoc read the same thing) Its the enzymes in their digestive track with the sudden change in their diet that gives them an intestinal infection or diarrhea that kills them when they are already stressed out during the winter.

My neighbors fed the deer during the winter and would feed them right up until the spring browse came in and I never seen a problem with it, till one winter they decided to go to Texas in January to stay the rest of the winter.
Within days after their supplemental feed ran out you could see them standing in the yard looking for their handout with Crap running down their hind quarters, not long after some of them began to Die, 2 right in the yard where they had been being feed, and a couple of others you could see from the road.

If you live in the north where the winters are harsh and the deer are stressed, I would not feed them unless I was committed to feeding them till their spring browse came in, thats all!